Publications by year
In Press
Cockcroft EJ, williams C, jackman S, armstrong N, barker A (In Press). Agreement and Reliability of Fasted and Oral Glucose Tolerance Test-Derived Indices of Insulin Sensitivity and Beta Cell Function in Boys. International journal of sports medicince
Suemi da Costa Rosa C, Gracia Marco L, Barker AR, Freitas Junior IF, Monteiro HL (In Press). Assessment of physical activity by accelerometer and IPAQ-short version in patients with chronic kidney disease undergoing hemodialysis. Blood Purification
Agbaje A, Barker A, Tuomainen T-P (In Press). Cardiorespiratory fitness, fat mass and cardiometabolic health with endothelial function, arterial elasticity, and stiffness. Medicine and Science in Sports and Exercise
Williams CAP, Vlachopoulos D, Ubago-Guisade E, Barker AR, Metcalf B, Fatouros IG, Avoniti A, Knapp K, Gracia-Marco L (In Press). Determinants of bone outcomes in adolescent athletes at baseline: the PRO-BONE study. Medicine and Science in Sports and Exercise
Weston M, Barker A, Tomlinson O, Coombes JS, Bailey TG, Bond B (In Press). Differences in cerebrovascular regulation and ventilatory responses during ramp incremental cycling in children, adolescents and adults. Journal of Applied Physiology
Williams C, Oliveira R, Barker A, Kranen S, Debras F (In Press). Effects of high-intensity interval training on the vascular and autonomic components of the baroreflex at rest in adolescents. Pediatric Exercise Science
Denford S, Mackintosh KA, McNarry MA, Barker AR, Williams CA (In Press). Enhancing intrinsic motivation for physical activity among adolescents with cystic fibrosis: a qualitative study of the views of healthcare professionals. BMJ Open
Fulford J, Juroskova V, Meakin JR, Barker AR (In Press). Muscle function and size in the lumbar spine before and after a four week exercise intervention. Journal of Back and Musculoskeletal Rehabilitation
Tomlinson O, Barker A, Fulford J, Wilson P, Oades P, Williams C (In Press). Quantification of thigh muscle volume in children and adolescents using magnetic resonance imaging. European Journal of Sport Science, 20, 1215-1224.
Williams C, Breese B, Saynor Z, Barker A, Armstrong N (In Press). RELATIONSHIP BETWEEN (NON)LINEAR PHASE II PULMONARY OXYGEN UPTAKE KINETICS WITH SKELETAL MUSCLE OXYGENATION AND AGE IN 11 TO 15 Y OLDS. Experimental Physiology
Wilkinson K, Vlachopoulos D, Klentrou P, Ubago-Guisado E, de Moraes AC, Barker AR, Williams CA, Moreno LA, Gracia Marco L (In Press). Soft tissues, areal bone mineral density and hip geometry estimates in active young boys: the PRO-BONE study. European Journal of Applied Physiology
Bond B, Koep J, Weston M, Barker A, Sansum K (In Press). The acute and postprandial effects of sugar moiety on vascular and metabolic health outcomes in adolescents. Applied Physiology, Nutrition and Metabolism
Bond B, Hind S, Williams CA, Barker AR (In Press). The acute effect of exercise intensity on vascular function in adolescents.
Medicine and Science in Sports and ExerciseAbstract:
The acute effect of exercise intensity on vascular function in adolescents
Introduction: Impairments in vascular function are present in asymptomatic youths with risk factors for cardiovascular disease. Exercise can promote vascular health in youth, but the effect of exercise intensity and the time course in response to acute exercise are unknown. Methods: Twenty adolescents (10 male, 14.1 ± 0.3 y) on separate days, and in a counter-balanced order: 1) cycled at 90% of the gas exchange threshold (moderate-intensity exercise; MIE); 2) completed 8x1 min cycling at 90% peak power with 75 s recovery (high-intensity interval exercise; HIIE). The duration of MIE (25.8 ± 2.1 min) was work-matched to HIIE (23.0 min). Macro- and micro-vascular function were assessed before, immediately post, and 1 and 2 hours after exercise by flow mediated dilation (FMD) and laser Doppler imaging (total reactive hyperaemia). Results: FMD was attenuated immediately after HIIE (P
Abstract.
Weston M, Barker A, Tomlinson O, Coombes J, Bailey T, Bond B (In Press). The effect of exercise intensity and cardiorespiratory fitness on the kinetic response of middle cerebral artery blood flow velocity during exercise in healthy adults. Journal of applied physiology
Constable A, Vlachopoulos D, Barker A, Moore S, Soininen S, Haapala E, Väist J, Westgate K, Brage S, Mahonen A, et al (In Press). The independent and interactive associations of physical activity intensity and vitamin D status with bone mineral density in prepubertal children: the PANIC Study. Osteoporosis International
Koep J, Bond B, Barker A, Ruediger S, Pizzey F, Coombes J, Bailey T (In Press). The relationships between age, sex and cerebrovascular reactivity to hypercapnia using traditional and kinetic-based analyses in healthy adults.
American Journal of Physiology - Heart and Circulatory PhysiologyAbstract:
The relationships between age, sex and cerebrovascular reactivity to hypercapnia using traditional and kinetic-based analyses in healthy adults
The effect of age and sex on intracranial and extracranial cerebrovascular function is poorly understood. We investigated the relationships between age, sex and cerebrovascular reactivity (CVR) to hypercapnia in 73 healthy adults (18-80 years, N=39 female). CVR to hypercapnia was assessed in the middle cerebral artery (MCA) using transcranial Doppler ultrasound and at the internal carotid artery (ICA) using duplex ultrasound. MCA CVR was characterised by peak MCA velocity (MCAv) response per mmHg increase in end-tidal CO2, and by using a mono-exponential model to characterize the kinetics (time-constant) of the MCAv response. ICA reactivity was assessed as the relative peak increase in artery diameter. Hierarchical multiple regression determined the relationships between age, sex, and the age by sex interaction on all baseline and CVR outcomes. There was no relationship between ICA reactivity (%) with age (P=0.07), sex (P=0.56) or a moderator effect of sex on the age effect (P=0.24). MCAv CVR showed no relationship with age (P=0.59), sex (P=0.09), or an age by sex moderator effect (P=0.90). We observed a positive relationship of MCAv CVR time-constant with age (P=0.013), such that the speed of the MCA response was slower with advancing age. The present study provides comprehensive data on age and sex specific relationships with intracranial and extracranial cerebrovascular responses to hypercapnia. Despite similar MCAv CVR and ICA reactivity between sexes, kinetic responses of the MCA revealed a slower rate of adjustment with advancing age.
Abstract.
Williams C, Barker A, Wadey C, Weston M, Dorobantu D (In Press). The role of cardiopulmonary exercise testing (CPET) in predicting mortality and morbidity in people with congenital heart disease: a systematic review and meta-analysis. European Journal of Preventive Cardiology
Bond B, Barker A, Koep J, Weston M, Lester A, Coombes J, Bailey T (In Press). The within and between-day reliability of cerebrovascular reactivity using traditional and novel analytical approaches.
Experimental PhysiologyAbstract:
The within and between-day reliability of cerebrovascular reactivity using traditional and novel analytical approaches
Cerebrovascular reactivity of the middle cerebral artery velocity (CVR MCAv) to carbon dioxide (CO2) is a common method to assess cerebrovascular function. Yet, the approaches used to calculate CVR outcomes vary. The aim of this study was to explore the within and between-day reliability of traditional CVR outcomes. The second aim was to explore the reliability of novel kinetic-based analyses. Healthy adults (n=10, 22.3±3.4 years) completed assessments of CVR over four minutes using a fixed fraction of inspired CO2 (6%). This was repeated across four separate visits (between-day), and on one visit measures were repeated 2.5 hours later (within-day). No mean biases were present between assessments for traditional CVR metrics, expressed as absolute (cm/s/mmHg) or relative (%/mmHg) outcomes (minute-3, minute-4, peak 1 second, peak 30 second) (between-day: P>0.14, ηp20.22, d>0.27). Absolute, rather than relative CVR, yielded the most reproducible parameters (coefficient of variation: 8.1-13.2% versus 14-83% respectively). There were significant differences between CVR outcomes (P0.89) dependent on the time point used to determine CVR, as a steady state MCAv response was rarely observed. Furthermore, the MCAv response was not reproducible within an individual (kappa=0.15, P=0.09). No mean differences were present for novel kinetic outcomes (amplitude, time-delay, time constant) (between-day: P>0.05, d0.38, d
Abstract.
Mann R, McKay C, Clift B, Anthony C, Barker A (In Press). Training Practices and Injuries in Competitive Adolescent Distance Runners: a Retrospective Cross-Sectional Study.
Abstract:
Training Practices and Injuries in Competitive Adolescent Distance Runners: a Retrospective Cross-Sectional Study
Background: Distance running is one of the most popular sports around the world. The epidemiology of running-related injuries (RRI) has been examined in adults, but only a few studies have focused on adolescent distance runners. Objectives: to examine the training practices (frequency, volume, and intensity) and epidemiology of RRI (rates, sites, severity, and risk factors) in competitive adolescent distance runners (13-18 years) in England. Methods: a cross-sectional study design was used. Adolescent distance runners (64 females) were recruited from England Athletics affiliated athletics clubs. Participants voluntarily completed an online questionnaire between April and December 2018. At the point of completion, responses were based on the participant’s previous 12-months of distance running participation. Injury incidence proportions (IP) and incidence rates (IR) were calculated. Potential injury risk factors were estimated using an odds ratio (OR) and 95% confidence intervals (CI). Results: the injury IP was 122/100 participants/year (95% CI: 113 to 138). The injury IR was 6.3/1000 participation hours (95% CI: 5.3 to 7.4). Univariate analyses showed a larger number of training sessions per week (volume) is associated with a reduced risk of RRI (OR=0.71, 95% CI: 0.53 to 0.94), and that a higher level of specialisation reduces the risk of time-loss injury (OR=0.26, 95% CI: 0.11 to 0.63). The most common injury sites were the knee, foot/toes, and lower leg; predominantly caused by overuse. Conclusion: Injury is common in adolescent distance runners, aligned with adult-based research. These data provide guidance for the development of appropriate injury prevention programmes.
Abstract.
Mann RH, McKay CD, Clift BC, Williams CA, Barker AR (In Press). Training Practices and Injuries in Competitive Adolescent Distance Runners: a Retrospective Cross-Sectional Study.
Abstract:
Training Practices and Injuries in Competitive Adolescent Distance Runners: a Retrospective Cross-Sectional Study.
Abstract
. Background: Distance running is one of the most popular sports around the world. The epidemiology of running-related injuries (RRI) has been examined in adults, but only a few studies have focused on adolescent distance runners. Therefore, the purpose of this study was 1) to examine the training practices (frequency, volume, and intensity) and descriptive epidemiology of RRI (risks, rates, sites, and severity) in competitive adolescent distance runners (13-18 years) in England, and 2) to explore potential correlates (risk factors) of RRI. Methods: a cross-sectional study design was used. Adolescent distance runners (n = 113) were recruited from England Athletics affiliated athletics clubs. Participants voluntarily completed an online questionnaire between April and December 2018. At the point of completion, responses were based on the participant’s previous 12-months of distance running participation. Injury incidence proportions (IP) and incidence rates (IR) were calculated. Potential correlates of RRI were estimated using an odds ratio (OR) and 95% confidence intervals (CI). Results: the injury IP was 122/100 participants/year (95% CI: 113 to 138). The injury IR was 6.3/1000 participation hours (95% CI: 5.3 to 7.4). The most common injury sites were the knee, foot/toes, and lower leg; primarily caused by overuse. Exploratory univariate analyses showed a larger number of training sessions per week (volume) is associated with a lower risk of RRI (OR = 0.71, 95% CI: 0.53 to 0.94), and that a higher level of specialisation is associated with a lower risk of time loss injury (OR = 0.26, 95% CI: 0.11 to 0.63). Conclusions: Injury is common in adolescent distance runners, aligned with adult-based research. These data provide guidance for the development of appropriate injury prevention interventions.
Abstract.
Denford S, Hill DM, Mackintosh KA, McNarry MA, Barker AR, Williams CA (In Press). Using photo-elicitation to explore perceptions of physical activity among young people with cystic fibrosis. BMC Pulmonary Medicine
2023
Skinner AM, Vlachopoulos D, Barker AR, Moore SA, Rowlands AV, Soininen S, Haapala EA, Väistö J, Westgate K, Brage S, et al (2023). Physical activity volume and intensity distribution in relation to bone, lean and fat mass in children.
Scand J Med Sci Sports,
33(3), 267-282.
Abstract:
Physical activity volume and intensity distribution in relation to bone, lean and fat mass in children.
Considering physical activity (PA) volume and intensity may provide novel insights into the relationships of PA with bone, lean, and fat mass. This study aimed to assess the associations of PA volume, PA intensity distribution, including moderate-to-vigorous PA (MVPA) with total-body-less-head bone mineral content (BMC), lean, and fat mass in children. A population sample of 290 Finnish children (158 females) aged 9-11 years from the Physical Activity and Nutrition in Children (PANIC) Study was studied. PA, including MVPA, was assessed with a combined heart rate and movement sensor, and the uniaxial acceleration was used to calculate average-acceleration (a proxy metric for PA volume) and intensity-gradient (reflective of PA intensity distribution). Linear regression analyzed the associations of PA volume, PA intensity and MVPA with BMC, lean mass, and fat mass assessed by dual-energy X-ray absorptiometry. PA volume was positively associated with BMC in females (unstandardised regression coefficient [ß] = 0.26) and males (ß = 0.47), and positively associated with lean (ß = 7.33) and negatively associated with fat mass in males (ß = -20.62). PA intensity was negatively associated with BMC in males (ß = -0.13). MVPA was positively associated with lean mass in females and males (ß = 0.007 to 0.012), and negatively associated with fat mass in females and males (ß = -0.030 to -0.029). PA volume may be important for improving BMC in females and males, and increasing lean and reducing fat mass in males, whereas MVPA may be important for favorable lean and fat outcomes in both sexes.
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Agbaje AO, Barmi S, Sansum KM, Baynard T, Barker AR, Tuomainen T-P (2023). Temporal longitudinal associations of carotid-femoral pulse wave velocity and carotid intima-media thickness with resting heart rate and inflammation in youth.
J Appl Physiol (1985),
134(3), 657-666.
Abstract:
Temporal longitudinal associations of carotid-femoral pulse wave velocity and carotid intima-media thickness with resting heart rate and inflammation in youth.
We examined the temporal longitudinal associations of carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (cIMT) with the risk of elevated resting heart rate (RHR) and high-sensitivity C-reactive protein (hsCRP). We studied 3,862 adolescents, mean age 17.7 (SD 0.3 yr), followed-up for 7 yr until age 24.5 (0.7) yr, from the Avon Longitudinal Study of Parents and Children, UK. RHR, fasting plasma hsCRP, cfPWV, and cIMT were repeatedly assessed and analyzed using logistic regression, linear mixed-effect, and structural equation models adjusting for important covariates. Among 3,862 adolescents [2,143 (55.5%) female], 10% and 44% were at moderate-to-high risk of elevated RHR and hsCRP at 24.5 yr, respectively. Higher cfPWV at 17.7 yr was associated with elevated RHR risk at follow-up [odds-ratio (OR) 1.58 (CI 1.20-2.08); P = 0.001], whereas cIMT at 17.7 yr was associated with elevated hsCRP risk [OR 2.30 (1.18-4.46); P = 0.014] at follow-up, only among females. In mixed model, 7-yr progression in cfPWV was directly associated with 7-yr increase in RHR [effect-estimate 6 beats/min (1-11); P = 0.017] and hsCRP. cIMT progression was associated with 7-yr increase in RHR and hsCRP. In cross-lagged model, higher cfPWV at 17.7 yr was associated with higher RHR (β = 0.06, standard error = 3.85, P < 0.0001) at 24.5 yr but RHR at 17.7 yr was unassociated with cfPWV at 24.5 yr. Baseline cIMT or RHR was unassociated with either outcome at follow-up. Higher hsCRP at 17.7 yr was associated with higher cfPWV and cIMT at 24.5 yr. In conclusion, adolescent arterial stiffness but not cIMT appears to precede higher RHR in young adulthood, whereas elevated hsCRP in adolescence preceded higher cfPWV and cIMT.NEW & NOTEWORTHY Higher arterial stiffness but not carotid-intima media thickness in adolescence preceded higher resting heart rate in young adulthood, however, elevated high sensitivity C-reactive protein in adolescence preceded higher arterial stiffness and carotid intima-thickness in young adulthood in the temporal causal path. Low-grade inflammation during adolescence may be causally associated with the development of subclinical arteriosclerosis and atherosclerosis in young adulthood.
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Skinner AM, Rowlands AV, Vlachopoulos D, Barker AR, Janz KF, Moore SA (2023). The Influence of Accelerometer Epoch Length on Associations of Physical Activity Intensity and Volume with Bone Outcomes.
Journal of Sports Science and Medicine, 117-132.
Abstract:
The Influence of Accelerometer Epoch Length on Associations of Physical Activity Intensity and Volume with Bone Outcomes
Two accelerometer metrics (intensity-gradient and average-acceleration) can be used to determine the relative contributions of physical activity (PA) volume and intensity for health, but it is unknown whether epoch length influences the associations detected. This is important when considering bone health, as bone is particularly responsive to high intensity PA, which may be underestimated by longer epochs. This study aimed to assess the associations between average-acceleration, a proxy measure of PA volume, and intensity-gradient, reflective of PA intensity distribution, from PA data from 1-s to 60-s epochs at age 17 to 23 years with bone outcomes at age 23 years. This is a secondary analysis of 220 participants (124 females) from the Iowa Bone Development Study, a longitudinal study of bone health from childhood to early adulthood. Accelerometer-assessed PA data, captured at age 17 to 23 years, were summarised over 1-s, 5-s, 15-s, 30-s, and 60-s epochs, to generate average-acceleration and intensity-gradient from each epoch length, averaged across ages. Regression analysed associations between mutually adjusted average-acceleration and intensity-gradient with dual-energy X-ray absorptiometry assessed total-body-less-head (TBLH) bone mineral content (BMC), spine areal bone mineral density (aBMD), hip aBMD, and femoral neck cross-sectional area and section modulus at age 23 years. Intensity-gradient was positively associated with TBLH BMC in females, with spine aBMD in males, and with hip aBMD and geometry in both sexes, when a 1 to 5-s epoch was used. Average-acceleration was positively associated with TBLH BMC, spine aBMD and hip aBMD in males, generally when the adjustment for intensity-gradient was from > 1-s epochs. Intensity and volume were important for bone outcomes in both sexes and males, respectively. A 1 to 5-s epoch length was most appropriate to assess the mutually adjusted associations of intensity-gradient and average-acceleration with bone outcomes in young adults.
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Kranen SH, Oliveira RS, Bond B, Williams CA, Barker AR (2023). The effect of 4 weeks of high‐intensity interval training and 2 weeks of detraining on cardiovascular disease risk factors in male adolescents. Experimental Physiology
2022
Bianchim MS, McNarry MA, Holland A, Cox NS, Dreger J, Barker AR, Williams CA, Denford S, Mackintosh KA (2022). A Compositional Analysis of Physical Activity, Sedentary Time, and Sleep and Associated Health Outcomes in Children and Adults with Cystic Fibrosis.
International Journal of Environmental Research and Public Health,
19(9), 5155-5155.
Abstract:
A Compositional Analysis of Physical Activity, Sedentary Time, and Sleep and Associated Health Outcomes in Children and Adults with Cystic Fibrosis
This study sought to investigate the association of light physical activity (LPA), moderate-to-vigorous physical activity (MVPA), sedentary time (SED), and sleep with lung function in children and adults with CF. In total, 86 children (41 females; 13.6 ± 2.8 years; FEV1%predicted: 86 ± 1%) and 43 adults (21 females; 24.6 ± 4.7 years; FEV1%predicted: 63 ± 21%) with CF participated in this study. Wrist-worn accelerometery was used to assess PA, SED and sleep. Compositional linear regression models were conducted following normalisation via isometric log-ratio transformations. Sequential binary partitioning was applied to investigate the impact of reallocating 10 to 30 min between each behaviour on FEV1%predicted. A decline in FEV1%predicted was predicted with the reallocation of 30 min from MVPA to SED or LPA or sleep to any other behaviour in children (−3.04–−0.005%) and adults (−3.58–−0.005%). Conversely, improvements in FEV1%predicted were predicted when 30 min was reallocated to MVPA from LPA or SED in children (0.12–1.59%) and adults (0.77–2.10%), or when 30 min was reallocated to sleep from any other behaviour in both children (0.23–2.56%) and adults (1.08–3.58%). This study supports the importance of MVPA and sleep for maintaining and promoting lung function in people with CF.
Abstract.
Agbaje AO, Barker AR, Tuomainen T-P (2022). Abstract 045: Adolescent Arterial Stiffness Precedes Elevated Resting Heart Rate in Young Adulthood: a 7-year Temporal Longitudinal Analysis Using Cross-lagged Structural Equation Model. Circulation, 145(Suppl_1).
Agbaje AO, Barker AR, Tuomainen T-P (2022). Abstract EP70: Adolescent Arterial Stiffness Precedes Elevated Resting Heart Rate in Young Adulthood: a 7-year Temporal Longitudinal Analysis Using Cross-lagged Structural Equation Model. Circulation, 145(Suppl_1).
Agbaje AO, Barker AR, Tuomainen T-P (2022). Adolescence arterial stiffness precedes elevated blood pressure in young adulthood: the ALSPAC birth cohort. Metabolism, 128
Agbaje AO, Barker AR, Tuomainen T-P (2022). Adolescence arterial stiffness precedes insulin resistance in young adulthood: a 7-year temporal longitudinal findings using cross-lagged structural equation model. Metabolism, 128
Sansum K (2022). Associations between physical activity and sedentary time with endothelial function, arterial stiffness, arterial elasticity, and clustered cardiometabolic risk in children: the ALSPAC Study.
Abstract:
Associations between physical activity and sedentary time with endothelial function, arterial stiffness, arterial elasticity, and clustered cardiometabolic risk in children: the ALSPAC Study
Introduction: Evidence for associations between physical activity (PA) or sedentary time (ST) and vascular health in paediatric populations is of low quality due to the predominance of self-report measures of PA time and intensities, small sample sizes, and a lack of control of confounding variables. This thesis examined associations between device-derived PA and ST with vascular outcomes and a clustered cardiometabolic risk (CMR) score in a population sample, with adjustment for covariates. Methods: Cross-sectional analysis of 4,277 children (2,226 girls) aged 10.6 ± 0.2 y from the Avon Longitudinal Study of Parents and Children. Clustered CMR was measured at age 9 y. Vascular outcomes (flow mediated dilation, distensibility coefficient, and pulse wave velocity) were measured age 10 y. Light and moderate to vigorous PA (MVPA) and ST were measured via accelerometers at age 11 y. Multiple linear regression analyses were used to examine associations between exposures and outcomes, with PA and ST entered as compositional exposure variables and non-compositional variables (min∙day-1). Results: Neither light PA, MVPA or ST were significantly associated with any of the vascular outcomes in the adjusted compositional and non-compositional models. The proportion of time spent in MVPA and ST (relative to the remaining activity behaviours) were inversely (b=-0.126; P=0.001) and positively (b=0.136; P=0.016) associated with CMR in the whole group analysis, respectively. MVPA was negatively associated with CMR in both boys (b=-0.144; P=0.011) and girls (b=-0.110; P=0.032), but only girls had a positive association between ST and CMR (b=0.199; P=0.005). In the non-compositional models, MVPA was inversely associated with CMR in the whole group analysis (b=-0.002; P=0.012). In the girls, ST was positively (b=0.001; P=0.035), and LPA was inversely (b=-0.001; P=0.035) associated with CMR. Conclusion: Longer exposure to CMR factors during adolescence may be needed to establish relationships between PA and ST with vascular outcomes. These findings support interventions that promote MVPA and minimise ST for reducing CMR in children. Prospective studies are required to understand the causal directions.
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Bianchim MS, McNarry MA, Evans R, Thia L, Barker AR, Williams CA, Denford S, Mackintosh KA (2022). Calibration and Cross-validation of Accelerometry in Children and Adolescents with Cystic Fibrosis. Measurement in Physical Education and Exercise Science, 27(1), 51-59.
Agbaje AO, Barker AR, Tuomainen T-P (2022). Cumulative muscle mass and blood pressure but not fat mass drives arterial stiffness and carotid intima-media thickness progression in the young population and is unrelated to vascular organ damage.
Hypertens ResAbstract:
Cumulative muscle mass and blood pressure but not fat mass drives arterial stiffness and carotid intima-media thickness progression in the young population and is unrelated to vascular organ damage.
We examined the longitudinal associations of fat mass, lean mass, and blood pressure (BP) from childhood through young adulthood with changes in carotid-femoral pulse wave velocity (cfPWV), a measure of arterial stiffness, and carotid intima-media thickness (cIMT). We included 3863 participants from the Avon Longitudinal Study of Parents and Children birth cohort. Fat mass and lean mass, measured by dual-energy X-ray absorptiometry, and BP were measured at ages 9, 17 and 24 years and classified into low, moderate, and high tertiles. cfPWV and cIMT were measured at 17 and 24 years of age. Associations were examined via linear mixed effect models and adjusted for cardiometabolic and lifestyle factors. Among 1720 [44.5%] male and 2143 [55.5%] female participants, cumulative high exposures to lean mass (effect estimate 0.006 m/s [95% CI 0.001 to 0.010; p = 0.022]), systolic BP (0.013 m/s [0.009 to 0.017; p
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Agbaje AO, Barmi S, Sansum KM, Baynard T, Barker AR, Tuomainen TP (2022). Does arterial stiffness progression temporally precede higher low-grade inflammation in adolescents? Causal longitudinal evidence using auto-regressive cross-lagged structural equation models. European Heart Journal, 43(Supplement_2).
Agbaje AO, Barker AR, Mitchell GF, Tuomainen T-P (2022). Effect of Arterial Stiffness and Carotid Intima-Media Thickness Progression on the Risk of Dysglycemia, Insulin Resistance, and Dyslipidemia: a Temporal Causal Longitudinal Study.
Hypertension,
79(3), 667-678.
Abstract:
Effect of Arterial Stiffness and Carotid Intima-Media Thickness Progression on the Risk of Dysglycemia, Insulin Resistance, and Dyslipidemia: a Temporal Causal Longitudinal Study.
BACKGROUND: We investigated the temporal causal longitudinal associations of carotid-femoral pulse wave velocity (cfPWV), a measure of arterial stiffness, and carotid intima-media thickness (cIMT) progression with the risk of dysglycemia, insulin resistance, and dyslipidemia. METHODS: We included 3862, 17.7-year-old, participants from the Avon Longitudinal Study of Parents and Children, followed up for 7 years. cfPWV, cIMT, and fasting plasma samples were repeatedly measured. We computed homeostatic model assessment (HOMA) of insulin resistance and percent pancreatic beta-cell function. Data were analyzed using logistic regression, linear mixed-effect, and cross-lagged structural equation models. RESULTS: a higher cfPWV at 17.7 years was associated with higher insulin at age 24.5 years (odds ratio, 1.25 [CI, 1.08-1.44]; P=0.003), which slightly attenuated after covariates adjustment. Higher cIMT at 17.7 years was associated with lower insulin (odds ratio, 0.06 [0.01-0.95]; P=0.046) at 24.5 years, after covariate adjustments. In mixed-effect models, the 7-year progression in cfPWV (predictor) was directly associated with the increase in triglyceride (outcome). cIMT progression was associated with the 7-year increase in LDL (low-density lipoprotein), triglyceride, and glucose. In cross-lagged models, higher cfPWV at 17.7 years was associated with higher insulin (β=0.06, SE, 0.12, P=0.014), HOMA of insulin resistance, and HOMA-percent pancreatic beta-cell function at 24.5 years. However, insulin, HOMA of insulin resistance, and HOMA-percent pancreatic beta-cell function at 17.7 years were not associated with cfPWV at 24.5 years. Higher cIMT at 17.7 years was associated with reduced insulin, HOMA of insulin resistance, and HOMA-percent pancreatic beta-cell function at 24.5 years, but not vice versa. Higher glucose at 17.7 years was associated with higher cfPWV and cIMT at 24.5 years only. CONCLUSIONS: Arterial stiffness in adolescence may be a causal risk factor for hyperinsulinemia and insulin resistance in young adulthood.
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Agbaje AO, Barker AR, Tuomainen T-P (2022). Effects of Arterial Stiffness and Carotid Intima-Media Thickness Progression on the Risk of Overweight/Obesity and Elevated Blood Pressure/Hypertension: a Cross-Lagged Cohort Study.
Hypertension,
79(1), 159-169.
Abstract:
Effects of Arterial Stiffness and Carotid Intima-Media Thickness Progression on the Risk of Overweight/Obesity and Elevated Blood Pressure/Hypertension: a Cross-Lagged Cohort Study
. We examined the temporal longitudinal associations of carotid-femoral pulse wave velocity (cfPWV), a measure of arterial stiffness, and carotid intima-media thickness (cIMT) with the risk of overweight/obesity and elevated blood pressure (BP)/hypertension. We studied 3862 adolescents aged 17.7 years from the Avon Longitudinal Study of Parents and Children, followed-up for 7 years. cfPWV and cIMT were measured by ultrasound. Total and trunk fat mass and lean mass were assessed by dual-energy X-ray absorptiometry. Body mass index and BP were measured. Data were analyzed using logistic regression, linear mixed-effect, and cross-lagged structural equation models, with covariate adjustments. Among 1719 male and 2143 female participants, higher cfPWV at 17.7 years was associated with the risk of elevated systolic BP/hypertension (odds ratio, 1.20 [1.02–1.41];
. P
. =0.026), elevated diastolic BP/hypertension (1.77 [1.32–2.38];
. P
. <0.0001), body mass index-overweight/obesity (1.19 [1.01–1.41];
. P
. =0.041), and trunk fat mass overweight/obesity (1.24 [1.03–1.49];
. P
. =0.023) at 24.5 years. Higher cIMT at 17.7 years had no associations with obesity and elevated BP at follow-up. cfPWV progression was directly associated with 7-year increase in systolic BP (effect estimate 16 mm Hg [9–24];
. P
. <0.0001) and diastolic BP (28 mm Hg [23–34];
. P
. <0.0001). cIMT progression was directly associated with the 7-year increase of all adiposity measures and diastolic BP. In the temporal analysis, baseline cfPWV was directly associated with follow-up systolic and diastolic BP, however, baseline BP was unassociated with follow-up cfPWV. cfPWV but not cIMT was bidirectionally associated with adiposity. Obesity and hypertension prevention from adolescence may require developing novel approaches to mitigate arterial stiffness.
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Caterini JE, Ratjen F, Barker AR, Williams CA, Rendall K, Schneiderman JE, Wells GD (2022). Exercise intolerance in cystic fibrosis-the role of CFTR modulator therapies.
Journal of Cystic Fibrosis,
21(2), 282-292.
Abstract:
Exercise intolerance in cystic fibrosis-the role of CFTR modulator therapies
Exercise intolerance is common in people with CF (pwCF), but not universal among all individuals. While associated with disease prognosis, exercise intolerance is not simply a reflection of the degree of lung disease. In people with severe CF, respiratory limitations may contribute more significantly to impaired exercise capacity than in those with mild-moderate CF. At all levels of disease severity, there are peripheral factors e.g. abnormal macro- and micro-vascular function that impair blood flow and reduce oxygen extraction, and mitochondrial defects that diminish metabolic efficiency. We discuss advances in understanding the central and peripheral mechanisms underlying exercise intolerance in pwCF. Exploring both the central and peripheral factors that contribute to exercise intolerance in CF can help inform the development of new therapeutic targets, as well as help define prognostic criteria.
Abstract.
Agbaje AO, Barker AR, Tuomainen T-P (2022). Fat mass paradox and carotid intima-media thickness progression: a longitudinal study from childhood through young adulthood. Metabolism, 128
Koep JL, Coombes JS, Barker AR, Taylor CE, Pizzey FK, Ruediger SL, Bond B, Bailey TG (2022). Intracranial Cerebrovascular Reactivity by Traditional and Novel Methods in Young, Middle, and Old Aged Healthy Males and Females. The FASEB Journal, 36(S1).
Agbaje AO, Barker AR, Tuomainen T-P (2022). Longitudinal and bi-directional associations of arterial stiffness with general and central fat mass from adolescence through young adulthood: the ALSPAC Study. Metabolism, 128
Duncombe SL, Barker AR, Price L, Walker JL, Dux PE, Fox A, Matthews N, Stylianou M (2022). Making a HIIT: study protocol for assessing the feasibility and effects of co-designing high-intensity interval training workouts with students and teachers.
BMC Pediatrics,
22(1).
Abstract:
Making a HIIT: study protocol for assessing the feasibility and effects of co-designing high-intensity interval training workouts with students and teachers
Abstract
. Background
. High-intensity interval training (HIIT) is an effective strategy for improving a variety of health outcomes within the school setting. However, there is limited research on the implementation of school-based HIIT interventions and the integration of HIIT within the Health and Physical Education (HPE) curriculum. The aims of the Making a HIIT study are to: 1) describe the methodology and evaluate the feasibility of co-designing HIIT workouts with students and teachers in HPE; 2) determine the effect of co-designed HIIT workouts on cardiorespiratory and muscular fitness, and executive function; 3) understand the effect of co-design on students’ motivation, enjoyment, and self-efficacy towards the workouts; and 4) evaluate the implementation of the intervention.
.
. Methods
. Three schools will participate. Within each school, three different groups will be formed from Year 7 and 8 classes: 1) Co-Designers; 2) HIIT Only; and 3) Control. The study will include two phases. In phase one, Group 1 will co-design HIIT workouts as part of the HPE curriculum using an iterative process with the researcher, teacher, and students as collaborators. This process will be evaluated using student discussions, student surveys, and teacher interviews. In phase two, Groups 1 and 2 will use the co-designed 10-minute HIIT workouts in HPE for 8-weeks. Group 3 (control) will continue their regular HPE lessons. All students will participate in cardiorespiratory fitness, muscular fitness, and executive function assessments before and after the HIIT program or control period. Students will complete questionnaires on their motivation, enjoyment, and self-efficacy of the workouts. Differences between groups will be assessed using linear regressions to account for covariates. Heart rate and rating of perceived exertion will be collected during each HIIT session. The implementation will be evaluated using the Framework for Effective Implementation. Ethical approval was granted by the University of Queensland Human Research Ethics Committee and other relevant bodies.
.
. Discussion
. This study will be the first to co-design HIIT workouts with teachers and students within the HPE curriculum. As this study relies on co-design, each HIIT workout will differ, which will add variability between HIIT workouts but increase the ecological validity of the study.
.
. Trial registration
. ACTRN, ACTRN12622000534785, Registered 5 April 2022 – Retrospectively registered, https://www.anzctr.org.au/ACTRN12622000534785.aspx
.
Abstract.
Caterini JE, Rendall K, Cifra B, Schneiderman JE, Ratjen F, Seed M, Rayner T, Weiss R, McCrindle BW, Noseworthy MD, et al (2022). Non-invasive MR imaging techniques for measuring femoral arterial flow in a pediatric and adolescent cohort.
Physiol Rep,
10(10).
Abstract:
Non-invasive MR imaging techniques for measuring femoral arterial flow in a pediatric and adolescent cohort.
Magnetic Resonance Imaging (MRI) is well-suited for imaging peripheral blood flow due to its non-invasive nature and excellent spatial resolution. Although MRI is routinely used in adults to assess physiological changes in chronic diseases, there are currently no MRI-based data quantifying arterial flow in pediatric or adolescent populations during exercise. Therefore the current research sought to document femoral arterial blood flow at rest and following exercise in a pediatric-adolescent population using phase contrast MRI, and to present test-retest reliability data for this method. Ten healthy children and adolescents (4 male; mean age 14.8 ± 2.4 years) completed bloodwork and resting and exercise MRI. Baseline images consisted of PC-MRI of the femoral artery at rest and following a 5 × 30 s of in-magnet exercise. To evaluate test-retest reliability, five participants returned for repeat testing. All participants successfully completed exercise testing in the MRI. Baseline flow demonstrated excellent reliability (ICC = 0.93, p = 0.006), and peak exercise and delta rest-peak flow demonstrated good reliability (peak exercise ICC = 0.89, p = 0.002, delta rest-peak ICC = 0.87, p = 0.003) between-visits. All three flow measurements demonstrated excellent reliability when assessed with coefficients of variance (CV's) (rest: CV = 6.2%; peak exercise: CV = 7.3%; delta rest-peak: CV = 7.1%). The mean bias was small for femoral arterial flow. There was no significant mean bias between femoral artery flow visits 1 and 2 at peak exercise. There were no correlations between age or height and any of the flow measurements. There were no significant differences between male and female participants for any of the flow measurements. The current study determined that peripheral arterial blood flow in children and adolescents can be evaluated using non-invasive phase contrast MRI. The MRI-based techniques that were used in the current study for measuring arterial flow in pediatric and adolescent patients demonstrated acceptable test-retest reliability both at rest and immediately post-exercise.
Abstract.
Author URL.
Bianchim MS, McNarry MA, Evans R, Thia L, Barker AR, Williams CA, Denford S, Mackintosh KA (2022). P218 Calibration and cross-validation of accelerometry in children and adolescents with cystic fibrosis. Journal of Cystic Fibrosis, 21
Alkhraiji MH, Barker AR, Williams CA (2022). Reliability and validity of using the global school-based student health survey to assess 24 hour movement behaviours in adolescents from Saudi Arabia.
Journal of sports sciences,
40(14), 1578-1586.
Abstract:
Reliability and validity of using the global school-based student health survey to assess 24 hour movement behaviours in adolescents from Saudi Arabia.
This study aimed to examine the reliability and validity of Global School-based Student Health Survey (GSHS) to measure 24-hour movement behaviours (moderate-to-vigorous physical activity - MVPA; sedentary behaviour in the form of recreational screen time - ST; and sleep) in Saudi Arabian youths. A total of 120 (50% female) participants aged 12-15 years old were recruited from eight Saudi public middle schools. Participants completed GSHS survey twice and wore GENEActiv accelerometers for seven consecutive days and completed a diary log. ICC indicated moderate reliability in all 24-hour movement behaviours (ICC = 0.41 - 0.60), whereas ST and sleep were strongly reliable for females only (ICC = 0.61 - 0.80). Kappa agreements for all 24-hr movement behaviours were moderate (k = 0.41 - 0.60), but fair in MVPA and ST for males only (k = 0.21 - 0.40). Spearman's indicated low validity (r = 0.1 - 0.3) in MVPA and sleep between GSHS and GENEActiv. However, kappa test results indicated poor-to-slight agreements (k =
Abstract.
Wadey CA, Barker AR, Stuart G, Tran DL, Laohachai K, Ayer J, Cordina R, Williams CA (2022). Scaling Peak Oxygen Consumption for Body Size and Composition in People with a Fontan Circulation.
Journal of the American Heart Association,
11(24).
Abstract:
Scaling Peak Oxygen Consumption for Body Size and Composition in People with a Fontan Circulation
. Background
.
. Peak oxygen consumption (peak
.
.
.
.
. V
. ̇
.
.
. O
. 2
.
.
. $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$
.
.
. ) is traditionally divided (“ratio‐scaled”) by body mass (BM) for clinical interpretation. Yet, it is unknown whether ratio‐scaling to BM can produce a valid size‐independent expression of peak
.
.
.
.
. V
. ̇
.
.
. O
. 2
.
.
. $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$
.
.
. in people with a Fontan circulation. Furthermore, people with a Fontan circulation have deficits in lean mass, and it is unexplored whether using different measures of body composition may improve scaling validity. The objective was to assess the validity of different scaling denominators (BM, stature, body surface area, fat‐free mass, lean mass, and appendicular lean mass using ratio and allometric scaling).
.
.
.
. Methods and Results
.
. Eighty‐nine participants (age: 23.3±6.7 years; 53% female) with a Fontan circulation had their cardiorespiratory fitness and body composition measured by cardiopulmonary exercise testing and dual‐energy x‐ray absorptiometry. Ratio and allometric (log‐linear regression) scaling was performed and Pearson correlations assessed scaling validity. Scaling denominators BM (
. r
. =−0.25,
. P
. =0.02), stature (
. r
. =0.46,
. P
. <0.001), and body surface area (0.23,
. P
. =0.03) were significantly correlated with their respective ratio‐scaled expressions of peak
.
.
.
.
. V
. ̇
.
.
. O
. 2
.
.
. $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$
.
.
. but fat‐free mass, lean mass, or appendicular lean mass were not (
. r
. ≤0.11;
. R
. 2
. =1%). Allometrically expressed peak
.
.
.
.
. V
. ̇
.
.
. O
. 2
.
.
. $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$
.
.
. resulted in no significant correlation with any scaling denominator (
. r
. =≤0.23;
. R
. 2
. =≤4%).
.
.
.
. Conclusions
.
. The traditional and accepted method of ratio‐scaling to BM is invalid because it fails to create a size‐independent expression of peak
.
.
.
.
. V
. ̇
.
.
. O
. 2
.
.
. $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$
.
.
. in people with a Fontan circulation. However, ratio‐scaling to measures of body composition (fat‐free mass, lean mass, and appendicular lean mass) and allometric techniques can produce size‐independent expressions of peak
.
.
.
.
. V
. ̇
.
.
. O
. 2
.
.
. $$ \dot{\mathrm{V}}{\mathrm{O}}_2 $$
.
.
. in people with a Fontan circulation.
.
.
Abstract.
Duncombe SL, Barker AR, Bond B, Earle R, Varley-Campbell J, Vlachopoulos D, Walker JL, Weston KL, Stylianou M (2022). School-based high-intensity interval training programs in children and adolescents: a systematic review and meta-analysis.
PLOS ONE,
17(5), e0266427-e0266427.
Abstract:
School-based high-intensity interval training programs in children and adolescents: a systematic review and meta-analysis
Purpose
1) to investigate the effectiveness of school-based high-intensity interval training (HIIT) interventions in promoting health outcomes of children and adolescents compared with either a control group or other exercise modality; and 2) to explore the intervention characteristics and process outcomes of published school-based HIIT interventions.
Methods
We searched Medline, Embase, CINAHL, SPORTDiscus, and Web of Science from inception until 31 March 2021. Studies were eligible if 1) participants aged 5–17 years old; 2) a HIIT intervention within a school setting ≥ 2 weeks duration; 3) a control or comparative exercise group; 4) health-related, cognitive, physical activity, nutrition, or program evaluation outcomes; and 5) original research published in English. We conducted meta-analyses between HIIT and control groups for all outcomes with ≥ 4 studies and meta-regressions for all outcomes with ≥ 10 studies. We narratively synthesised results between HIIT and comparative exercise groups.
Results
Fifty-four papers met eligibility criteria, encompassing 42 unique studies (35 randomised controlled trials; 36 with a high risk of bias). Meta-analyses indicated significant improvements in waist circumference (mean difference (MD) = -2.5cm), body fat percentage (MD = -1.7%), body mass index (standardised mean difference (SMD) = -1.0), cardiorespiratory fitness (SMD = +1.0), resting heart rate (MD = -5bpm), homeostatic model assessment–insulin resistance (MD = -0.7), and low-density lipoprotein cholesterol (SMD = -0.9) for HIIT compared to the control group. Our narrative synthesis indicated mixed findings between HIIT and other comparative exercise groups.
Conclusion
School-based HIIT is effective for improving several health outcomes. Future research should address the paucity of information on physical activity and nutrition outcomes and focus on the integration and long-term effectiveness of HIIT interventions within school settings.
Trial registration number
PROSPERO CRD42018117567.
Abstract.
Bianchim MS, McNarry MA, Barker AR, Williams CA, Denford S, Holland AE, Cox NS, Dreger J, Evans R, Thia L, et al (2022). Sleep, Sedentary Time and Physical Activity Levels in Children with Cystic Fibrosis.
International Journal of Environmental Research and Public Health,
19(12), 7133-7133.
Abstract:
Sleep, Sedentary Time and Physical Activity Levels in Children with Cystic Fibrosis
The aim of this study was to compare the use of generic and cystic fibrosis (CF)-specific cut-points to assess movement behaviours in children and adolescents with CF. Physical activity (PA) was assessed for seven consecutive days using a non-dominant wrist-worn ActiGraph GT9X in 71 children and adolescents (36 girls; 13.5 ± 2.9 years) with mild CF. CF-specific and generic Euclidean norm minus one (ENMO) cut-points were used to determine sedentary time (SED), sleep, light physical activity (LPA), moderate physical activity and vigorous physical activity. The effect of using a CF-specific or generic cut-point on the relationship between PA intensities and lung function was determined. Movement behaviours differed significantly according to the cut-point used, with the CF-specific cut-points resulting in less time asleep (−31.4 min; p < 0.01) and in LPA (−195.1 min; p < 0.001), and more SED and moderate-to-vigorous PA (159.3 and 67.1 min, respectively; both p < 0.0001) than the generic thresholds. Lung function was significantly associated with LPA according to the CF-specific cut-points (r = 0.52; p = 0.04). Thresholds developed for healthy populations misclassified PA levels, sleep and SED in children and adolescents with CF. This discrepancy affected the relationship between lung function and PA, which was only apparent when using the CF-specific cut-points. Promoting LPA seems a promising strategy to enhance lung function in children and adolescents with CF.
Abstract.
Agbaje AO, Barmi S, Sansum KM, Baynard T, Barker AR, Tuomainen TP (2022). Temporal causal longitudinal associations of high-sensitivity C-reactive protein with carotid intima-media thickness progression in adolescents: the ALSPAC birth cohort study. European Heart Journal, 43(Supplement_2).
Williams CA, Barker AR, Denford S, van Beurden SB, Bianchim MS, Caterini JE, Cox NS, Mackintosh KA, McNarry MA, Rand S, et al (2022). The Exeter Activity Unlimited statement on physical activity and exercise for cystic fibrosis: methodology and results of an international, multidisciplinary, evidence-driven expert consensus.
Chron Respir Dis,
19Abstract:
The Exeter Activity Unlimited statement on physical activity and exercise for cystic fibrosis: methodology and results of an international, multidisciplinary, evidence-driven expert consensus.
BACKGROUND: the roles of physical activity (PA) and exercise within the management of cystic fibrosis (CF) are recognised by their inclusion in numerous standards of care and treatment guidelines. However, information is brief, and both PA and exercise as multi-faceted behaviours require extensive stakeholder input when developing and promoting such guidelines. METHOD: on 30th June and 1st July 2021, 39 stakeholders from 11 countries, including researchers, healthcare professionals and patients participated in a virtual conference to agree an evidence-based and informed expert consensus about PA and exercise for people with CF. This consensus presents the agreement across six themes: (i) patient and system centred outcomes, (ii) health benefits, iii) measurement, (iv) prescription, (v) clinical considerations, and (vi) future directions. The consensus was achieved by a stepwise process, involving: (i) written evidence-based synopses; (ii) peer critique of synopses; (iii) oral presentation to consensus group and peer challenge of revised synopses; and (iv) anonymous voting on final proposed synopses for adoption to the consensus statement. RESULTS: the final consensus document includes 24 statements which surpassed the consensus threshold (>80% agreement) out of 30 proposed statements. CONCLUSION: This consensus can be used to support health promotion by relevant stakeholders for people with CF.
Abstract.
Author URL.
Constable A, Vlachopoulos D, Barker A (2022). The Mediating Role of Endocrine Factors in the Positive Relationship Between Fat Mass and Bone Mineral Content in Children Aged 9–11 Years: the Physical Activity and Nutrition in Children Study.
Frontiers in EndocrinologyAbstract:
The Mediating Role of Endocrine Factors in the Positive Relationship Between Fat Mass and Bone Mineral Content in Children Aged 9–11 Years: the Physical Activity and Nutrition in Children Study
Introduction: We aimed to investigate whether the relationship between fat mass and bone mineral content (BMC) is mediated by insulin, leptin, adiponectin, dehydroepiandrosterone sulphate, testosterone and estradiol in children aged 9-11 years.
Materials and Methods: We utilised cross-sectional data from the Physical Activity and Nutrition in Children study (n = 230 to 396; 112 to 203 girls). Fat mass and BMC were assessed with dual-energy X-ray absorptiometry. Endocrine factors were assessed from fasted blood samples. We applied the novel 4-way decomposition method to analyse associations between fat mass, endocrine factors, and BMC.
Results: Fat mass was positively associated with BMC in girls (ß = 0.007 to 0.015, 95% confidence interval (CI) 0.005 to 0.020) and boys (ß = 0.009 to 0.015, 95% CI 0.005 to 0.019). The relationship between fat mass and BMC was mediated by free leptin index in girls (ß = -0.025, 95% CI -0.039 to -0.010) and boys (ß = -0.014, 95% CI -0.027 to -0.001). The relationship between fat mass and BMC was partially explained by mediated interaction between fat mass and free leptin index in boys (ß = -0.009, 95% CI -0.013 to -0.004) and by interaction between fat mass and adiponectin in girls (ß = -0.003, 95% CI -0.006 to -0.000).
Conclusion: at greater levels of adiponectin and free leptin index, the fat mass and BMC relationship becomes less positive in girls and boys respectively. The positive association between fat mass with BMC was largely not explained by the endocrine factors we assessed.
Clinical Trial Registration: [https://clinicaltrials.gov/ct2/show/NCT01803776], identifier NCT01803776.
Keywords: adiposity, insulin, leptin, adiponectin, DXA (dual-energy X-ray absorptiometry), paediatric
Abstract.
Weston M, Koep J, Lester A, Barker A, Bond B (2022). The acute effect of exercise intensity on peripheral and cerebral vascular function in healthy adults.
Journal of applied physiologyAbstract:
The acute effect of exercise intensity on peripheral and cerebral vascular function in healthy adults
The acute effect of exercise intensity on cerebrovascular reactivity, and whether this mirrors changes in peripheral vascular function, has not been investigated. The aim of this study was to explore the acute effect of exercise intensity on cerebrovascular reactivity (CVR) and peripheral vascular function in healthy young adults (n=10, 6 females, 22.7 ± 3.5 years). Participants completed four experimental conditions on separate days: high intensity interval exercise (HIIE) with intervals performed at 75% maximal oxygen uptake (V̇O2max; HIIE1), HIIE with intervals performed at 90% V̇O2max (HIIE2), continuous moderate intensity exercise (MIE) at 60% V̇O2max and a sedentary control condition (CON). All exercise conditions were completed on a cycle ergometer and matched for time (30 min) and average intensity (60% V̇O2max). Brachial artery flow-mediated dilation (FMD) and CVR of the middle cerebral artery were measured before exercise, and one- and three hours post-exercise. CVR was assessed using transcranial Doppler ultrasonography to both hypercapnia (6% carbon dioxide breathing) and hypocapnia (hyperventilation). FMD was significantly elevated above baseline one and three hours following both HIIE conditions (P0.33). CVR to both hypercapnia and hypocapnia, and when expressed across the end-tidal CO2 range, was unchanged in all conditions, at all time points (all P>0.14). In conclusion, these novel findings show that the acute increases in peripheral vascular function following HIIE, compared to MIE, were not mirrored by changes in cerebrovascular reactivity, which was unaltered following all exercise conditions in healthy young adults.
Abstract.
Harpham C, Harpham QK, Barker AR (2022). The effect of exercise training programs with aerobic components on C-reactive protein, erythrocyte sedimentation rate and self-assessed disease activity in people with ankylosing spondylitis: a systematic review and meta-analysis.
Int J Rheum Dis,
25(6), 635-649.
Abstract:
The effect of exercise training programs with aerobic components on C-reactive protein, erythrocyte sedimentation rate and self-assessed disease activity in people with ankylosing spondylitis: a systematic review and meta-analysis.
AIM: to examine the effect of exercise training programs with aerobic components on C-reactive protein, erythrocyte sedimentation rate and self-assessed disease activity in people with ankylosing spondylitis compared to non-aerobic rehabilitation. METHODS: a systematic review was undertaken of PubMED, Cochrane Library, Embase and Web of Science databases. Articles evaluating the effect of exercise training programs with aerobic components on C-reactive protein, erythrocyte sedimentation rate or Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in adults (>17 years) with ankylosing spondylitis were included. Control groups were defined as non-aerobic rehabilitation, including usual care or physiotherapy. RESULTS: Thirteen articles met inclusion criteria for qualitative and meta-analysis, involving 366 participants undertaking exercise and 361 controls. Exercise programs included modalities such as running, aerobic walking and swimming, and were between 3 weeks and 3 months in duration. Exercise programs significantly reduced C-reactive protein (weighted mean difference [WMD]: -1.09; 95% CI: -2.08 to -0.10; P = .03; n = 5) and BASDAI (WMD: -0.78; 95% CI: -0.98 to -0.58; P
Abstract.
Author URL.
Kranen S (2022). Vascular function in adolescents: the effect of exercise and new measurement approaches.
Abstract:
Vascular function in adolescents: the effect of exercise and new measurement approaches
Cardiovascular diseases (CVD) are the leading cause of non-communicable deaths worldwide. It is well established that atherosclerosis, as a precursor to overt CVD, originates in youth. Vascular endothelial function has been identified as a ‘novel’ risk factor for CVD and can be non-invasively assessed using flow-mediated dilation (FMD). It has been shown that exercise improves vascular function, however, children and adolescents fail to meet the recommended daily physical activity levels. Therefore, it is important to identify the optimal exercise strategy to improve vascular function.
In adults, new vascular measurements such as low-flow-mediated constriction (L-FMC) have been established to supplement the information gained from the measurement of FMD. Furthermore, the near-infrared spectroscopy (NIRS)-derived reperfusion rate of tissue oxygen saturation (slope 2 StO2) has been shown to be reliable and significantly correlated with FMD in adults, suggesting it may have utility to assess vascular function.
Therefore, Chapters 4 and 5 are concerned with acute and chronic exercise, respectively, while Chapters 6 and 7 investigate novel assessments of vascular function and their reliability in a paediatric population.
Chapter 4 demonstrates that both macro- and microvascular function were enhanced following an acute bout of interval running independent of exercise intensity in a group of adolescents, suggesting that the exercise pattern (i.e. interval) and the accompanying shear are important for vascular improvements. In addition, an acute glucose load improved macrovascular function whereas no changes in FMD were observed with a prior bout of exercise. The effect of a chronic exercise intervention on traditional and novel CVD risk factors in adolescent boys was examined in Chapter 5. Four weeks of high-intensity interval training improved FMD significantly with no concomitant changes in microvascular function or traditional risk factors (glucose, insulin, blood lipids, body composition), suggesting the training duration was too short to elicit further enhancements. However, the improvements in FMD were lost two weeks after training cessation.
Chapter 6 showed that the brachial artery of adolescents constricts during a period of low flow, however, on an individual level low-flow vasoreactivity is inconsistent between days. The measurement of L-FMC has poor reliability compared to FMD and no significant correlation was observed between FMD and L-FMC.
Finally, Chapter 7 revealed that the reliability of the NIRS-derived slope 2 StO2 is comparable to the reproducibility of FMD in male adolescents. However, slope 2 StO2 was not significantly correlated with FMD and therefore its use as a surrogate measure for FMD is precluded. In contrast to FMD, slope 2 StO2 was not sensitive to an acute bout of high-intensity interval exercise.
In conclusion, this thesis demonstrates that the intermittent stimulus may be more important than the exercise intensity with regards to improvements in vascular function. In addition, enhancements of traditional CVD risk factors are not achievable within four weeks of training in healthy adolescents despite improvements in FMD. Improvements in vascular function were lost after two weeks of detraining, highlighting the importance of regular exercise for promoting vascular health. While the reproducibility of L-FMC in adolescents is poor, slope 2 StO2 can be measured reliably in adolescents. However, due to the lack of correlation with FMD, slope 2 StO2 may not be used as a measure of macrovascular function.
Abstract.
Duncombe S, Barker AR, Price L, Walker JL, Stylianou M (2022). Was it a HIIT? a process evaluation of a school-based high-intensity interval training intervention. Journal of Science and Medicine in Sport, 25
2021
Agbaje AO, Barker AR, Tuomainen T-P (2021). 1244Associations of endothelial function, arterial elasticity, and arterial stiffness with adiponectin and skeletal muscle mass. International Journal of Epidemiology, 50(Supplement_1).
Mann R, Clarsen B, McKay C, Clift B, Williams C, Barker A (2021). 304 Prevalence and burden of health problems in competitive adolescent distance runners: a 6-month prospective cohort study. Poster Presentations.
Mann R, McKay C, Barker A, Williams C, Clift B (2021). 469 Running-related injury in competitive adolescent distance runners: a qualitative study of psychosocial responses. Poster Presentations.
Agbaje AO, Barker AR, Tuomainen T-P (2021). Abstract 080: a 15-year Cumulative High Exposure to Lean Mass and Blood Pressure but not Fat Mass predicts the 7-year change in Carotid-Femoral Pulse Wave Velocity and Carotid Intima-Media Thickness: the ALSPAC study. Circulation, 143(Suppl_1).
Agbaje AO, Barker AR, Tuomainen T-P (2021). Abstract 11483: a 7-Year Arterial Stiffness and Carotid Intima-Media Thickness Progression Predict Obesity, High Lean Mass, and Incident Hypertension from Age 17.7 to 24.5 Years: the ALSPAC Study. Circulation, 144(Suppl_1), a11483-a11483.
Agbaje AO, Barker AR, Tuomainen T-P (2021). Abstract 13236: Differing Relations of Arterial Stiffness and Carotid Intima-Media Thickness in Adolescence with Metabolic Risks in Young Adulthood: the ALSPAC Study. Circulation, 144(Suppl_1), a13236-a13236.
Smail O (2021). Acute and Long-Term Effects of Resistance Exercise on Dynamic Cerebral Autoregulation.
Abstract:
Acute and Long-Term Effects of Resistance Exercise on Dynamic Cerebral Autoregulation
Dynamic cerebral autoregulation (dCA) describes the active maintenance of cerebral blood flow (CBF) in response to rapid, systemic blood pressure (BP) fluctuations. dCA capacity has been linked to neurological pathologies such as dementia, stroke and traumatic brain injury and may be implicated as a target for therapeutic strategies. Resistance exercise is a common leisure activity with growing popularity and forms the basis for many strength sports as well as being recommended by public health institutions. Heavy resistance exercise is known to induce large transient increases in BP which are translated into elevations in CBF. dCA must act effectively to minimise the BP oscillations which are translated into the cerebrovasculature, however CBF is still significantly elevated which indicates that it is not entirely effective at maintaining a constant CBF. This begs the question: does resistance exercise lead to altered dCA capacity both acutely and/ or at baseline following years of training? This thesis is formed of two main sections. Firstly, the within- and between-day reliability of dCA metrics phase, gain and normalised gain at each phase of the cardiac cycle were determined using repeat squat-stand manoeuvres (SSM) to elicit orthostatic BP fluctuations. As dCA can be induced, measured and analysed with a variety of methods, understanding the reliability of the measures used is crucial when interpreting one’s results. SSM were utilised to elicit BP fluctuations at 0.05 and 0.10Hz due to the excellent signal-to-noise ratio which they produce. The novelty of this work is largely attributed to the exploration of dCA metrics during systole and diastole as well as mean values, both within- and between-day. Secondly, the acute effects of resistance exercise and long-term effects of regular resistance exercise on dCA are examined. Long-term effects were inferred by comparing phase, gain and normalised gain in resistance trained vs. recreationally active individuals by use of SSM in a rested condition. Acute effects were explored by comparing phase, gain and normalised gain pre-exercise to follow-up measures 10 and 45 minutes post-
3
exercise in both groups. The exercise protocol consisted of four sets of ten repetition back squats at 70% of the individuals one-repetition maximum. This work indicates that dCA induced by SSM at 0.05 and 0.10Hz produce excellent reproducibility of phase, gain and normalised gain within- and between-day when measured as the mean of the cardiac cycle. Diastolic and systolic outcomes were also largely reproducible, although notably less so than mean values. Cross-sectional analysis of baseline dCA between groups found no significant differences in phase, gain or normalised gain at any phase of the cardiac cycle. Furthermore, no group interaction effect was identified in response to an acute bout of resistance exercise, suggesting that the post-exercise effects on dCA were similar in both demographics. dCA was largely unaltered following resistance exercise; however, gain and normalised gain were significantly elevated when measured as the mean and systolic section of the cardiac cycle during 0.10Hz SSM only. This difference was only present 10, but not 45 minutes post-exercise which indicates rapid recovery towards baseline. Further research is warranted, but these preliminary findings suggest that resistance exercise may acutely impair sympathetic nervous activity responsible for CBF regulation, although this does not appear to lead to alterations at baseline.
Abstract.
Agbaje AO, Barker AR, Tuomainen T-P (2021). Arterial stiffness and carotid intima-media thickness in relation to cardiometabolic health in adolescence: the ALSPAC study. Atherosclerosis, 331
Agbaje AO, Barker AR, Tuomainen TP (2021). Arterial stiffness in adolescence predicts elevated blood pressure in young adulthood: the ALSPAC study. European Heart Journal, 42(Supplement_1).
Agbaje AO, Barker AR, Tuomainen T-P (2021). Association of Fat Mass, Lean Mass, Body Mass Index, and Blood Pressure with Carotid-Femoral Pulse Wave Velocity and Carotid Intima-Media Thickness in Young Adults: the ALSPAC study. Metabolism, 116
Agbaje AO, Barker AR, Tuomainen T-P (2021). Association of carotid-femoral pulse wave velocity and carotid intima-media thickness with cardiometabolic risks among young adults: the Alspac study. Atherosclerosis, 331, e20-e21.
Agbaje AO, Barker AR, Tuomainen T-P (2021). Associations of Endothelial Function, Arterial Elasticity, and Arterial Stiffness with Cardiorespiratory Fitness and Fat Mass. Medicine & Science in Sports & Exercise, 53(8S), 191-192.
Mann R (2021). Health and Wellbeing in Competitive Adolescent Distance Runners: Training Load, Health Problems, and Psychosocial Response to Injury.
Abstract:
Health and Wellbeing in Competitive Adolescent Distance Runners: Training Load, Health Problems, and Psychosocial Response to Injury
Although distance running is associated with multiple health benefits, adult-based research indicates that participation is also associated with unfavourable health outcomes, such as running-related injury (RRI). As there is limited literature related to the health problems (i.e. injury and illness) that competitive adolescent distance runners (13-18 years) experience, this research aimed to describe and evaluate the extent of the injury and illness problem in competitive adolescent distance runners in England.
The first study (Chapter 4) demonstrates that session rating of perceived exertion (sRPE), whether reported 0, 15, or 30 minutes following session completion, provides a valid measure of internal training load in adolescent distance runners. This allows sRPE to be used during training and future epidemiological studies. The second study (Chapters 5 and 6) employed a mixed-methods study design. Chapter 5 presents a retrospective epidemiological study (n = 113), whereby the incidence of RRI was 6.3 per 1,000 hours of exposure and the most commonly injured body areas were the knee, foot/toes, and lower leg. Exploratory univariate analyses indicated that a larger number of training sessions per week (volume) and higher specialisation (i.e. intense, year-round training in a single sport with the exclusion of other sports) were both associated with a lower risk of RRI. Chapter 6 investigated psychosocial responses to RRI in those athletes (n = 19) who self-reported a serious RRI (>28 days-6 months of time loss). Based upon a reflexive thematic analysis of interview data, fifteen codes and three themes were developed. These data indicate that serious RRI acts to ‘destabilise athletic identity’ in competitive adolescent distance runners. The third study (Chapter 7) presents a prospective cohort study (n = 136), whereby the incidence of RRI was 25 per 1,000 hours of exposure. At any time, the mean weekly prevalence of all health problems was 24%, regardless of type or sex, reducing to 11% and 4% for substantial and time loss health problems, respectively. These data show that competitive adolescent distance runners are likely to be training and/or competing whilst concurrently experiencing one or more health problems. Also, female athletes self-reported more illnesses, when compared to male athletes. Collectively, these studies provide valuable and novel insight into the health and wellbeing of competitive adolescent distance runners in England. In turn, this thesis will support the development of injury and illness prevention measures.
Abstract.
Mann RH, McKay CD, Clift BC, Williams CA, Barker AR (2021). Injuries and Training Practices in Competitive Adolescent Distance Runners: a Retrospective Cross-Sectional Study.
Frontiers in Sports and Active Living,
3Abstract:
Injuries and Training Practices in Competitive Adolescent Distance Runners: a Retrospective Cross-Sectional Study
Background: Distance running is one of the most popular sports around the world. The epidemiology of running-related injury (RRI) has been investigated in adults, but few studies have focused on adolescent distance runners.Objectives: (1) to provide descriptive epidemiology of RRI (risks, rates, body regions/areas, and severity) and examine the training practices (frequency, volume, and intensity) of competitive adolescent distance runners (13–18 years) in England, and (2) to describe potential risk factors of RRI.Methods: a cross-sectional study design was used. Adolescent distance runners (n = 113) were recruited from England Athletics affiliated clubs. Participants voluntarily completed an online questionnaire between April and December 2018. At the time of completion, responses were based on the participant's previous 12-months of distance running participation. Incidence proportions (IP) and incidence rates (IR) were calculated.Results: the IP for “all RRI” was 68% (95% CI: 60–77), while the IR was 6.3/1,000 participation hours (95% CI: 5.3–7.4). The most commonly injured body areas were the knee, foot/toes, and lower leg; primarily caused by overuse. The number of training sessions per week (i.e. frequency) significantly increased with chronological age, while a large proportion of participants (58%) self-reported a high level of specialisation.Conclusions: RRI is common in competitive adolescent distance runners. These descriptive data provide guidance for the development of RRI prevention measures. However, analytical epidemiology is required to provide better insight into potential RRI risk factors in this specific population.
Abstract.
Agbaje AO, Barker AR, Tuomainen T-P (2021). LONGITUDINAL ASSOCIATIONS OF FAT MASS, LEAN MASS, BODY MASS INDEX AND BLOOD PRESSURE FROM CHILDHOOD THROUGH YOUNG ADULTHOOD WITH CAROTID-FEMORAL PULSE WAVE VELOCITY AND CAROTID INTIMA-MEDIA THICKNESS AT AGE 24.5 YEARS. Journal of the American College of Cardiology, 77(18).
Mann RH, Clarsen BM, McKay CD, Clift BC, Williams CA, Barker AR (2021). Prevalence and burden of health problems in competitive adolescent distance runners: a 6-month prospective cohort study. Journal of Sports Sciences, 39(12), 1366-1375.
Haapala EA, Barker AR, Lakka TA (2021). Response. Medicine and Science in Sports and Exercise, 53(2).
Barker A, Bond B, Duncombe S, Earle R, Stylianou M, Varley-Campbell J, Vlachopoulos D, Walker J, Weston K (2021). School-based high-intensity interval training programs in children and adolescents: a Systematic Review and Meta-Analysis. Journal of Science and Medicine in Sport, 24, s78-s79.
Constable AM, Porter JE, Benger D, Vlachopoulos D, Barker AR, Moore SA, Soininen S, Haapala EA, Westgate K, Brage S, et al (2021). The Positive Relationship between Moderate-to-Vigorous Physical Activity and Bone Mineral Content is Not Mediated by Free Leptin Index in Prepubertal Children: the PANIC Study.
International Journal of Environmental Research and Public Health,
18(10), 5365-5365.
Abstract:
The Positive Relationship between Moderate-to-Vigorous Physical Activity and Bone Mineral Content is Not Mediated by Free Leptin Index in Prepubertal Children: the PANIC Study
Purpose: Moderate-to-vigorous physical activity (MVPA) positively influences bone mineral content (BMC) in prepubertal children, but it is unknown whether this relationship is partially mediated by free leptin index. The aim of this study was to examine whether the relationship between MVPA and total body less head (TBLH) BMC is mediated or moderated by free leptin index in prepubertal children. Methods: We performed a cross-sectional analysis on 401 children (194 girls) from baseline examinations of the Physical Activity and Nutrition in Childhood Study. We applied the four-way decomposition mediation analysis method to assess whether free leptin index, measured from fasted blood samples, mediated the relationship between accelerometer-measured MVPA and TBLH BMC measured by dual-energy X-ray absorptiometry. Results: MVPA had a positive controlled direct effect on TBLH BMC in girls and boys (β = 0.010 to 0.011, p < 0.05). There was no mediation or interaction between MVPA, free leptin index and TBLH BMC in girls or boys (β = −0.000 to 0.001, p > 0.05). Conclusion: Our study indicates that MVPA positively influences TBLH BMC through pathways not related to free leptin index in predominantly normal-weight prepubertal children, likely primarily through mechanical loading. The relationships between MVPA, free leptin index and TBLH BMC may be influenced by other factors such as pubertal status and adiposity, so it is unknown whether these observations extend to overweight and obese children at different stages of puberty.
Abstract.
Kranen SH, Oliveira RS, Bond B, Williams CA, Barker AR (2021). The acute effect of high‐ and moderate‐intensity interval exercise on vascular function before and after a glucose challenge in adolescents. Experimental Physiology, 106(4), 913-924.
Tomlinson OW, Denford S, Barker AR, Schneiderman JE, Campisi ES, Douglas H, Rand S, McNarry MA, Mackintosh KA, Williams CA, et al (2021). The impact of physical activity and exercise interventions for physical health in people with cystic fibrosis: protocol for a systematic review.
Systematic Reviews,
10(1).
Abstract:
The impact of physical activity and exercise interventions for physical health in people with cystic fibrosis: protocol for a systematic review
Abstract
. Background
. Cystic fibrosis (CF) is a genetically inherited, life-limiting condition, affecting ~90,000 people globally. Physical activity (PA) and exercise form an integral component of CF management, and have been highlighted by the CF community as an area of interest for future research. Previous reviews have solely focused on PA or structured exercise regimens independent of one another, and thus a comprehensive assessment of the physical health benefits of all PA, including exercise, interventions, is subsequently warranted. Therefore, the purpose of this review is to evaluate the effects of both PA and exercise upon outcomes of physical health and healthcare utilisation in people with CF.
.
. Methods
. A systematic review has been registered and reported in line with Preferred Reporting Items for Systematic Reviews and Meta-Analysis-P guidelines. This will include randomised control trials on the effects of PA and exercise, relative to usual treatment, upon people with CF. Primary outcomes will include variables associated with fitness, PA, lung health, inflammation, body composition, glycaemic control and patient-reported outcomes. Secondary outcomes will include adverse events and healthcare utilisation. Searches will be undertaken in Ovid MEDLINE, OVID EMBASE, PsychINFO, ERIC, SPORTDiscus, ASSIA, CCTR, CINHAL and Web of Science databases, and will be searched from date of inception onwards. Two reviewers will independently screen citations and abstracts, and full-texts, for inclusion and data extraction, respectively. Methodological quality will be assessed using the Cochrane Risk of Bias-2 tool. If feasible, random-effects meta-analyses will be conducted where appropriate. Additional analyses will explore potential sources of heterogeneity, such as age, sex, and disease severity.
.
. Discussion
. This systematic review will build on previous research, by comprehensively assessing the impact of both PA and exercise upon physical health and healthcare utilisation in people with CF. Results of this review will be utilised to inform discussions that will ultimately result in a consensus document on the impact of physical activity and exercise for people with CF.
.
. Systematic review registration
. PROSPERO CRD42020184411
.
Abstract.
Williams CA, Barker AR (2021). The role of physical activity, exercise, and fitness in medicine. In (Ed) Exercise and Respiratory Diseases in Paediatrics, 1-20.
2020
Mann R, Barker A, Williams C, Clift B (2020). 307 the prevalence and burden of health problems in competitive adolescent distance runners: a prospective study in England. British Journal of Sports Medicine, 54(Suppl 1).
Bianchim MS, McNarry MA, Larun L, Barker AR, Williams CA, Mackintosh KA (2020). Calibration and validation of accelerometry using cut-points to assess physical activity in paediatric clinical groups: a systematic review. Preventive Medicine Reports, 19, 101142-101142.
Blackwood E (2020). HEALTH AND WELL-BEING OF YOUNG DINGHY SAILORS.
Abstract:
HEALTH AND WELL-BEING OF YOUNG DINGHY SAILORS
Dinghy sailing, although frequently researched at elite and developmental levels, lacked research focused on the foundation levels in children. This thesis employed qualitative and quantitative methods to investigate the impact of dinghy sailing on children during a taster session, a beginner sailing course and those who were participating regularly on a weekly basis. While individualising each study to focus upon specific aspects, mental and physical wellbeing were common themes across all three studies.
In Study 1, participants (n=66; boys n= 35 and girls n= 31) aged between 8-13 years (10.5 ±0.6 y) completed the Daily Reconstruction Method for Children (DRM-C) and Before and After Feeling and Thoughts (BAFT) questionnaire. Key findings consisted of a general increase in both happiness and enjoyment from pre-to post- taster session. Sex comparisons found boys utilised sport more to assist in mental wellbeing even though girls expressed greater changes in emotion during taster session.
In Study 2 children (n=52) aged 10.3 (±2.7) y attended a RYA Stage 1 (n= 43), and/or Stage 2 (n= 27) course and participated in the DRM-C and BAFT questionnaire, as well as wearing wrist worn accelerometers and heart rate monitors. Overall, results in the morning sessions showed a decrease in emotions compared to afternoon sessions. In particular, the first afternoon (session 2) of both stage 1 and 2 recorded significant increases in happiness for both boys and girls. Physically, participants accrued 44% of their moderate to vigorous physical activity (MVPA) recommended guideline during their stage 1 and/ or 2 course. Overall, increased levels of physical activity was found for boys compared to girls.
In Study 3, youth sailors (n=12) with a mean age 11 ± 1.54 y, who sailed regularly (at least once a week) were interviewed to investigate a range of topics related to their journey in participation of dinghy sailing. Findings reported multiple positive areas present from starting to sail to regular participation including environment exposure, improved mental wellbeing, improved physical wellbeing, developed social skills, developed life skills, learnt sailing specific skills and assisted in school/ career ideas. The current study also found some negative areas including restraints in time and social factors, expenses, risk of injury/ hazards, and limitations in sailing performance to other areas of life. In relation to the recent document of Sport England for sports to establish evidence of benefits of sports participation, this study provides evidence to support the promotion of dinghy sailing for young people in physical wellbeing, mental wellbeing, individual and social development.
Abstract.
Malik AA, Williams CA, Weston KL, Barker AR (2020). Influence of personality and self-efficacy on perceptual responses during high-intensity interval exercise in adolescents. Journal of Applied Sport Psychology, 33(6), 590-608.
Agbaje AO, Barker AR, Tuomainen T-P (2020). Mediating role of cardiorespiratory fitness on the association of cardiometabolic health with endothelial function, arterial elasticity and arterial stiffness in 9-11-year olds: the ALSPAC study. Atherosclerosis, 315, e181-e182.
Tomlinson OW, Barker AR, Trott J, Oades PJ, Withers NJ, Williams CA (2020). P298 Annual changes in aerobic fitness are biased between normative equations in children and adolescents with cystic fibrosis. Journal of Cystic Fibrosis, 19, S139-S139.
Williams C, Denford S, Tomlinson O, Barker A, McNarry M, Mackintosh K, Cox N, Holland A, O'Halloran P (2020). Physical activity for cystic fibrosis: perceptions of people with cystic fibrosis, parents and healthcare professionals. ERJ Open Research, 6
Banger R (2020). The Vascular Response to Consumption of Different Sugar Types in Adolescents.
Abstract:
The Vascular Response to Consumption of Different Sugar Types in Adolescents
Cardiovascular disease (CVD) is the leading global cause of mortality and the underlying atherosclerotic disease process which precedes overt CVD originates in youth. Consumption of sugar-sweetened beverages (SSB) are associated with CVD risk factors in youth and SSB intake is a key contributor to added dietary sugar intake in teenagers in the United Kingdom. Endothelial dysfunction is a prerequisite for atherosclerosis and previous research demonstrates that SSB consumption acutely impairs endothelial function. However, these studies have predominantly focused on adult populations, or have used a glucose bolus which is not representative of the sugar found in commercially available SSBs. The purpose of this thesis was to investigate the influence of different dietary sugars found in SSBs on macrovascular and microvascular outcomes and then observe whether the sugar type influences the cardiometabolic responses to a subsequent test meal challenge. This thesis also determined the reliability of measures for the assessment of macrovascular (flow-mediated dilation; FMD) and microvascular (laser Doppler flowmetry) function. Chapter 4: Assessed the within-day and between day reliability of the simultaneous assessment of macrovascular and microvascular function. The within-day and between-day typical error expressed as a coefficient of variation were as follows: FMD, 7.2% and 8.0%; peak reactive hyperaemia (PRH), 24.5% and 26.1%. These results determined that the reliability of outcomes in this study were consistent with existing paediatric data. Chapter 5: There was a large (ηp2=0.27) but not significant (P=0.06) interaction effect for FMD. There was a non-significant difference between the sucrose and control trials for FMD at 1 hour post drink consumption (P=0.06) and 3 hours post test meal consumption (P=0.09) but there was a medium effect at both times with effect sizes of 0.77 and 0.65, respectively, where FMD increased following sucrose consumption. PRH increased 1 hour post drink consumption in the fructose (P=0.01), glucose (P=0.04) and sucrose trials (P=0.04) when compared to control. PRH was greater in the fructose trial when compared to the control (P=0.03), glucose (P=0.01) and sucrose (P=0.02) trials. These findings suggest that SSB intake acutely improves macro- and micro- vascular function in adolescents. Overall, these findings provide important information in regards to the effects of SSBs on macrovascular and microvascular function in adolescents.
Abstract.
Tallon CM, Barker AR, Nowak-Flück D, Ainslie PN, McManus AM (2020). The influence of age and sex on cerebrovascular reactivity and ventilatory response to hypercapnia in children and adults.
Exp Physiol,
105(7), 1090-1101.
Abstract:
The influence of age and sex on cerebrovascular reactivity and ventilatory response to hypercapnia in children and adults.
NEW FINDINGS: What is the central question of this study? in this study, we investigated intracranial cerebrovascular and ventilatory reactivity to 6% CO2 in children and adults and explored dynamic ventilatory and cerebrovascular onset responses. What is the main finding and its importance? We showed that cerebrovascular reactivity was similar in children and adults, but the intracranial blood velocity onset response was markedly attenuated in children. Sex differences were apparent, with greater increases in intracranial blood velocity in females and lower ventilatory reactivity in adult females. Our study confirms the importance of investigating dynamic onset responses when assessing the influence of development on cerebrovascular regulation. ABSTRACT: the purpose of this study was to compare the integrated intracranial cerebrovascular reactivity (CVR) and hypercapnic ventilatory response between children and adults and to explore the dynamic response of the middle cerebral artery mean velocity (MCAV ). Children (n = 20; 9.9 ± 0.7 years of age) and adults (n = 21; 24.4 ± 2.0 years of age) completed assessment of CVR over 240 s using a fixed fraction of inspired CO2 (0.06). Baseline MCAV was higher in the adult females compared with the males (P ≤ 0.05). The MCAV was greater in female children compared with male children (P ≤ 0.05) and in female adults compared with male adults (P ≤ 0.05) with hypercapnia. Relative CVR was similar in children and adults (3.71 ± 1.06 versus 4.12 ± 1.32% mmHg-1 ; P = 0.098), with absolute CVR being higher in adult females than males (3.27 ± 0.86 versus 2.53 ± 0.70 cm s-1 mmHg-1 ; P ≤ 0.001). Likewise, the hypercapnic ventilatory response did not differ between the children and adults (1.89 ± 1.00 versus 1.77 ± 1.34 l min-1 mmHg-1 ; P = 0.597), but was lower in adult females than males (1.815 ± 0.37 versus 2.33 ± 1.66 l min-1 mmHg-1 ; P ≤ 0.05). The heart rate response to hypercapnia was greater in children than in adults (P = 0.001). A monoexponential regression model was used to characterize the dynamic onset, consisting of a delay term, amplitude and time constant (τ). The results revealed that MCAV τ was faster in adults than in children (34 ± 18 versus 74 ± 28 s; P = 0.001). Our study provides new insight into the impact of age and sex on CVR and the dynamic response of the MCAV to hypercapnia.
Abstract.
Author URL.
Koep JL, Barker AR, Banks R, Banger RR, Sansum KM, Weston ME, Bond B (2020). The reliability of a breath‐hold protocol to determine cerebrovascular reactivity in adolescents. Journal of Clinical Ultrasound, 48(9), 544-552.
Wadey CA, Weston ME, Dorobantu DM, Taylor RS, Pieles GE, Barker AR, Williams CA (2020). The role of cardiopulmonary exercise testing (CPET) in predicting mortality and morbidity in people with congenital heart disease: a systematic review and meta-analysis (Protocol).
Journal of Congenital Cardiology,
4(1).
Abstract:
The role of cardiopulmonary exercise testing (CPET) in predicting mortality and morbidity in people with congenital heart disease: a systematic review and meta-analysis (Protocol)
Abstract
Background
Numerous studies have measured the prognostic associations between cardiorespiratory fitness and patient outcomes in congenital heart disease, but no systematic review has assessed these associations for all types of congenital heart disease. It is therefore a timely opportunity to syntheses all available data using a systematic review methodology. The aim of this study is to detail the protocol for a systematic review and meta-analysis.
Objectives
Within this paper we have developed a protocol for a prognostic factors systematic review and meta-analysis, to assess the role of cardiopulmonary exercise testing/cardiorespiratory fitness, in the prognosis of mortality and morbidity in congenital heart disease.
Methods
We have outlined, in detail, the process for this systematic review using the latest accepted methodological guidelines for prognostic factors research, such as the PICOTS system, CHARMS-PF data extraction, QUIPS risk of bias assessments and the prognostic GRADE guidelines (see list of abbreviations).
Conclusion
The implications of this review will aid future treatments, interventions and individual patient risk prediction. The publication of this protocol aims to improve scientific rigour by ensuring transparency in the systematic review and meta-analysis process.
Abstract.
Williams CA, Tomlinson OW, Withers NJ, Oades PJ, Barker AR (2020). WS16.4 Differences in the ventilatory response to incremental exercise in people with cystic fibrosis according to age and sex. Journal of Cystic Fibrosis, 19, S27-S28.
2019
Cox NS, Eldridge B, Rawlings S, Dreger J, Corda J, Hauser J, Button BM, Bishop J, Nichols A, Middleton A, et al (2019). A web-based intervention to promote physical activity in adolescents and young adults with cystic fibrosis: protocol for a randomized controlled trial.
BMC Pulm Med,
19(1).
Abstract:
A web-based intervention to promote physical activity in adolescents and young adults with cystic fibrosis: protocol for a randomized controlled trial.
BACKGROUND: Regular participation in physical activity by people with cystic fibrosis (CF) promotes positive clinical and health outcomes including reduced rate of decline in lung function, fewer hospitalizations and greater wellbeing. However adherence to exercise and activity programs is low, in part due to the substantial daily therapy burden for young people with CF. Strict infection control requirements limit the role of group exercise programs that are commonly used in other clinical groups. Investigation of methods to promote physical activity in this group has been limited. The Active Online Physical Activity in Cystic fibrosis Trial (ActionPACT) is an assessor-blinded, multi-centre, randomized controlled trial designed to compare the efficacy of a novel web-based program (ActivOnline) compared to usual care in promoting physical activity participation in adolescents and young adults with CF. METHODS: Adolescents and young adults with CF will be recruited on discharge from hospital for a respiratory exacerbation. Participants randomized to the intervention group will have access to a web-based physical activity platform for the 12-week intervention period. ActivOnline allows users to track their physical activity, set goals, and self-monitor progress. All participants in both groups will be provided with standardised information regarding general physical activity recommendations for adolescents and young adults. Outcomes will be assessed by a blinded assessor at baseline, after completion of the intervention, and at 3-months followup. Healthcare utilization will be assessed at 12 months from intervention completion. The primary outcome is change in moderate-to-vigorous physical activity participation measured objectively by accelerometry. Secondary outcomes include aerobic fitness, health-related quality of life, anxiety and depression and sleep quality. DISCUSSION: This trial will establish whether a web-based application can improve physical activity participation more effectively than usual care in the period following hospitalization for a respiratory exacerbation. The web-based application under investigation can be made readily and widely available to all individuals with CF, to support physical activity and exercise participation at a time and location of the user's choosing, regardless of microbiological status. TRIAL REGISTRATION: Clinical trial registered on July 13, 2017 with the Australian and New Zealand Clinical Trials Register at (ACTRN12617001009303).
Abstract.
Author URL.
Abdul Malik A (2019). Adolescents’ perceptual and physiological responses to high-intensity interval exercise.
Abstract:
Adolescents’ perceptual and physiological responses to high-intensity interval exercise
High-intensity interval exercise (HIIE) has been shown to promote multiple health benefits and well-being in youth. However, HIIE is proposed to elicit negative affect responses (unpleasant feelings) as predicted by the dual mode theory (DMT), and may negatively impact on future exercise adherence. Previous studies have explored how perceptual, physiological and cognitive factors are associated to negative affect responses during continuous high-intensity exercise, but affect experience (pleasure/displeasure) during HIIE is poorly understood in adolescents. The purpose of this thesis is to evaluate acute affect responses to HIIE in adolescents, and to examine the influence of physiological (i.e. heart rate (HR) and prefrontal cortex (PFC)), perceptual (i.e. enjoyment and rating of perceived exertion (RPE)), and cognitive (i.e. self-efficacy and personality traits) factors. Chapter 4 demonstrates that HIIE (work intervals performed at 90% of peak power (PPO)) is perceived to be more enjoyable due to elevated feelings of reward, excitement and success than continuous moderate-intensity exercise, which was perceived to be more boring in adolescents. Chapter 5 examined the acute affect, enjoyment and RPE responses to HIIE (work intervals performed at 90% of maximal aerobic speed) compared with moderate-intensity interval exercise (MIIE). Chapter 5 reports that HIIE elicits less pleasurable feelings at the later stages of work intervals but greater post-enjoyment than MIIE, extending and reinforcing the findings in Chapter 4. The findings from Chapter 5 are furthered in Chapters 6 and 7, which identified that the affect responses during HIIE are dependent on the intensity and delivery (decreasing vs increasing) of the HIIE protocol. Chapter 6 revealed that HIIE performed at 100% PPO elicited a greater decline and lower affect responses across all work intervals than HIIE performed at 85% and 70% PPO. However, all HIIE conditions generated similar enjoyment responses during and after exercise. Chapter 7 showed that affect and enjoyment responses improve (more pleasurable and enjoyable) near the end of HIIE with decreasing work intensity compared to HIIE with increasing work intensity. Moreover, the increases in positive affect experienced during HIIE were positively related to an increase in PFC oxygenation. Chapters 5-7 also demonstrate that RPE and HR responses were inversely related to changes in the affect responses in all HIIE conditions. Finally, Chapter 8 identified that both individual self-efficacy and personality traits may decrease or increase the likelihood that a person will experience positive affective and enjoyment responses to HIIE at the later stages of work intervals in adolescents. Collectively, the studies presented in this thesis demonstrate that affect responses during HIIE are dependent on the work intensity, work delivery, and changes in enjoyment, RPE, PFC oxygenation and cognitive factors. Given that some permutations of HIIE protocols do not elicit prominent and entirely negative affective responses, HIIE protocols could serve as a strategy to encourage exercise adoption and promote health benefits in adolescents.
Abstract.
Du Rietz E, Barker AR, Michelini G, Rommel A-S, Vainieri I, Asherson P, Kuntsi J (2019). Beneficial effects of acute high-intensity exercise on electrophysiological indices of attention processes in young adult men.
Behav Brain Res,
359, 474-484.
Abstract:
Beneficial effects of acute high-intensity exercise on electrophysiological indices of attention processes in young adult men.
BACKGROUND: Emerging research suggests that a single bout of aerobic exercise can improve cognition, brain function and psychological health. Our aim was to examine the effects of high-intensity exercise on cognitive-performance and brain measures of attention, inhibition and performance-monitoring across a test-battery of three cognitive tasks. METHOD: Using a randomised cross-over design, 29 young men completed three successive cognitive tasks (Cued Continuous Performance Task [CPT-OX]; Eriksen Flanker Task; four-choice reaction-time task [Fast Task]) with simultaneous electroencephalogram (EEG) recording before and after a 20-min high-intensity cycling exercise and resting control session. Cognitive-performance measures, EEG power and event-related potential measures, were obtained during the tasks. Random-intercept linear models were used to investigate the effects of exercise, compared to rest, on outcomes. RESULTS: a single bout of exercise significantly (p
Abstract.
Author URL.
Tomlinson OW (2019). Cardiopulmonary exercise testing in the assessment and treatment of young people with cystic fibrosis.
Abstract:
Cardiopulmonary exercise testing in the assessment and treatment of young people with cystic fibrosis
Cystic fibrosis (CF) is the most common, genetically inherited, life-shortening condition in the Caucasian population, with ~11,000 people in the United Kingdom having the disease. The genetic defect responsible for CF results in accumulation of thick, sticky mucus that blocks the airways and digestive systems. As there is currently no cure for CF, it is a disease that is managed using antibiotics, nutrition, physiotherapy and exercise. Exercise capacity, as measured by peak oxygen uptake (V̇O2peak), and where possible, maximal oxygen uptake (V̇O2max), is reduced in patients with CF and a low V̇O2peak is associated with increased risk of hospitalisation, mortality and low quality of life. As a result, regular exercise testing is recommended, with cardiopulmonary exercise testing (CPET) considered the ‘gold standard’ procedure by leading international clinical organisations. The purpose of this thesis was to further our understanding surrounding the use of CPET in the assessment and treatment of children and adolescents with CF.
The first component of this thesis sought to identify and evaluate submaximal parameters of aerobic function derived from CPET, namely the oxygen uptake efficiency slope (OUES) and plateau (OUEP). Findings revealed that allometric scaling for body surface area (BSA) was necessary when evaluating OUES, and a power function of 1.40 (i.e. OUES/BSA1.40) removed residual effects of body size (Chapter 4). Subsequently, results identified that the OUES was not a valid surrogate of aerobic fitness in CF, despite a significant correlation (r = 0.47, p = 0.004) with V̇O2max when expressed relative to body mass, as it was unable to discriminate aerobic fitness within a CF group, nor against a control group (Chapter 5). As OUES was not a valid surrogate of aerobic fitness, the utility of OUEP as an independent marker of aerobic fitness was explored. Whilst the OUEP was correlated with V̇O2peak in CF, when expressed as an absolute value (r = 0.43, p = 0.010) and when allometrically scaled for body mass (r = 0.52, p = 0.001), it was unable to discriminate aerobic fitness to the same extent as V̇O2peak. However, the OUEP was associated with disease status and severity, being significantly (p < 0.001) lower in the CF group, but also significantly and positively correlated with lung function (forced expiratory volume in one-second [FEV1]) in the CF group (r = 0.43, p = 0.010), a finding that warrants further, longitudinal investigation (Chapter 6).
The second component of this thesis utilised CPET to investigate musculoskeletal limitations to the reduced V̇O2max that has previously been reported in CF. Parameters of muscle size (thigh cross-sectional area, muscle cross-sectional area and thigh muscle volume) were first quantified using magnetic resonance imaging, alongside the error associated with estimating muscle volume using alternative calculation techniques (Chapter 7). These parameters were then allometrically scaled for, which successfully removes residual effects of muscle size (i.e. muscle ‘quantity’) from V̇O2max. When this scaling is undertaken, V̇O2max is lower in children with CF relative to age- and sex-matched controls, indicating that exercise capacity is not size-dependent in CF and that intrinsic muscular factors (i.e. muscle ‘quality’) are likely responsible for the reduced V̇O2max observed in CF (Chapter 8).
Finally, the third component identified applications of CPET for both patients with CF and staff responsible for care. CPET, using a case-study approach, was utilised to describe exercise-related changes in an 11 year old female with CF following surgical insertion of a percutaneous endoscopic gastrostomy and overnight nutritional supplementation. This evaluation identified a maintenance of V̇O2max over one year, in contrast to a fluctuation in FEV1, and increase in body mass index (BMI), therefore highlighting the independent prognostic information afforded by use of CPET (Chapter 9). Following this patient-centred application of CPET, two meetings were held with NHS staff, to provide a platform for exchange of ideas and best practice, but to also survey roles, responsibilities, prevalence of CPET and resources needed for effective implementation of exercise testing and training (Chapter 10).
In conclusion, this thesis has further highlighted the utility of CPET in the management of CF. Moreover, it has explored the prognostic and diagnostic properties of CPET, as well as its implementation for patients and staff alike.
Abstract.
Tomlinson O, Barker A, Williams C (2019). Cardiopulmonary exercise testing in young people with cystic fibrosis. The Sport and Exercise Scientist, 61, 22-22.
HAAPALA EA, WIKLUND P, LINTU N, TOMPURI T, VÄISTÖ J, FINNI T, TARKKA IM, KEMPPAINEN T, BARKER AR, EKELUND ULF, et al (2019). Cardiorespiratory Fitness, Physical Activity, and Insulin Resistance in Children. Medicine & Science in Sports & Exercise, 52(5), 1144-1152.
Farr C, Middlebrooke AR, Armstrong N, Barker AR, Fulford J, Mawson DM, McManus AM (2019). Caution with Conclusions Required: a Response to the Paper "Objectively Measured Aerobic Fitness is not related to Vascular Health Outcomes and Cardiovascular Disease Risk in 9-10 Year Old Children" response.
JOURNAL OF SPORTS SCIENCE AND MEDICINE,
18(4), 831-833.
Author URL.
Ubago-Guisado E, Vlachopoulos D, Barker AR, Christoffersen T, Metcalf B, Gracia-Marco L (2019). Effect of maturational timing on bone health in male adolescent athletes engaged in different sports: the PRO-BONE study.
J Sci Med Sport,
22(3), 253-258.
Abstract:
Effect of maturational timing on bone health in male adolescent athletes engaged in different sports: the PRO-BONE study.
OBJECTIVES: to describe differences in bone outcomes according to biological age in male athletes participating in osteogenic (OS) or non-osteogenic (NOS) sports. DESIGN: Longitudinal (12-months). METHODS: 104 adolescents (12-14years) were measured at baseline and after 1y: OS group (n=37 football or soccer players) and NOS group (n=39 swimmers, n=28 cyclists). Years from peak height velocity (PHV, -2 to +2) was used as a maturational landmark. Bone mineral content (BMC) was assessed using DXA. Hip structural analysis estimated cross-sectional area (CSA), cross-sectional moment of inertia (CSMI) and section modulus (Z) at the femoral neck (FN). Trabecular bone score (TBS) estimated lumbar spine (LS) texture. Quantitative ultrasound measured bone stiffness. Multilevel regression models adjusted by hours of training were fitted. RESULTS: Compared to NOS, OS had significantly greater total body (less head) BMC from PHV to +2years from PHV (from 9.5% to 11.3%, respectively); LS BMC from -1years from PHV to PHV (from 9.8% to 9.9%); hip BMC (from 11.6% to 22.9%), FN BMC (from 12.0% to 15.9%), TBS (from 4.2% to 4.8%) and stiffness index (from 11.9% to 23.3%) from -1years from PHV to +2years from PHV; and CSA (from 8.4% to 18.8%), Z (from 5.5% to 22.9%) and CSMI (from 10.6% to 23.3%) from -2years from PHV to +2years from PHV. There was a significant trend for the between-group differences to increase with biological age except for LS BMC and TBS. CONCLUSIONS: These findings underline the differential bone response to different sports throughout the years surrounding PHV in male adolescent athletes. CLINICAL TRIAL REGISTRATION: ISRCTN17982776.
Abstract.
Author URL.
Oliveira RS, Barker AR, Debras F, Kranen SH, Williams CA (2019). Effects of exercise intensity on vascular and autonomic components of the baroreflex following glucose ingestion in adolescents.
Eur J Appl Physiol,
119(4), 867-878.
Abstract:
Effects of exercise intensity on vascular and autonomic components of the baroreflex following glucose ingestion in adolescents.
PURPOSE: to investigate the effects of an oral glucose tolerance test (OGTT) on baroreflex sensitivity (BRS) in a sample of healthy adolescents, and how acute exercise bouts of different intensities alter the effects of the OGTT on BRS. METHODS: Thirteen male adolescents (14.0 ± 0.5 years) completed three conditions on separate days in a counterbalanced order: (1) high-intensity interval exercise (HIIE); (2) moderate-intensity interval exercise (MIIE); and (3) resting control (CON). At ~ 90 min following the conditions, participants performed an OGTT. Supine heart rate and blood pressure were monitored continuously at baseline, 60 min following the conditions, and 60 min following the OGTT. A cross-spectral method (LFgain) was used to determine BRS gain. Arterial compliance (AC) was assessed as the BRS vascular component. LFgain divided by AC (LFgain/AC) was used as the autonomic component. RESULTS: Although non-significant, LFgain moderately decreased post-OGTT when no exercise was performed (pre-OGTT = 24.4 ± 8.2 ms mmHg- 1; post-OGTT = 19.9 ± 5.6 ms mmHg- 1; ES = 0.64, P > 0.05). This was attributed to the decrease in LFgain/AC (pre-OGTT = 1.19 ± 0.5 ms µm- 1; post-OGTT = 0.92 ± 0.24 ms µm- 1; ES = 0.69, P > 0.05). Compared to CON (Δ = - 4.4 ± 8.7 ms mmHg- 1), there were no differences for the pre-post-OGTT delta changes in LF/gain for HIIE (Δ = - 3.5 ± 8.2 ms mmHg- 1) and MIIE (Δ = 1.3 ± 9.9 ms mmHg- 1) had no effects on BRS following the OGTT (all ES
Abstract.
Author URL.
Dirks ML, Wall BT, Otten B, Cruz AM, Dunlop MV, Barker AR, Stephens FB (2019). High-fat Overfeeding Does Not Exacerbate Rapid Changes in Forearm Glucose and Fatty Acid Balance During Immobilization.
The Journal of Clinical Endocrinology & Metabolism,
105(1), 276-289.
Abstract:
High-fat Overfeeding Does Not Exacerbate Rapid Changes in Forearm Glucose and Fatty Acid Balance During Immobilization
Abstract
.
. Context
. Physical inactivity and high-fat overfeeding have been shown to independently induce insulin resistance.
.
.
. Objective
. Establish the contribution of muscle disuse and lipid availability to the development of inactivity-induced insulin resistance.
.
.
. Design, Setting, Participants, and Interventions
. 20 healthy males underwent 7 days of forearm cast immobilization combined with a fully controlled eucaloric diet (n = 10, age 23 ± 2 yr, body mass index [BMI] 23.8 ± 1.0 kg·m-2) or a high-fat diet (HFD) providing 50% excess energy from fat (high-fat diet, n = 10, age 23 ± 2 yr, BMI 22.4 ± 0.8 kg·m-2).
.
.
. Main Outcome Measures
. Prior to casting and following 2 and 7 days of immobilization, forearm glucose uptake (FGU) and nonesterified fatty acid (NEFA) balance were assessed using the arterialized venous–deep venous (AV-V) forearm balance method following ingestion of a mixed macronutrient drink.
.
.
. Results
. 7 days of HFD increased body weight by 0.9 ± 0.2 kg (P = 0.002), but did not alter fasting, arterialized whole-blood glucose and serum insulin concentrations or the associated homeostatic model assessment of insulin resistance or Matsuda indices. Two and 7 days of forearm immobilization led to a 40 ± 7% and 52 ± 7% decrease in FGU, respectively (P &lt; 0.001), with no difference between day 2 and 7 and no effect of HFD. Forearm NEFA balance tended to increase following 2 and 7 days of immobilization (P = 0.095).
.
.
. Conclusions
. Forearm immobilization leads to a rapid and substantial decrease in FGU, which is accompanied by an increase in forearm NEFA balance but is not exacerbated by excess dietary fat intake. Altogether, our data suggest that disuse-induced insulin resistance of glucose metabolism occurs as a physiological adaptation in response to the removal of muscle contraction.
.
Abstract.
Vlachopoulos D, Barker A, Williams C, Gracia-Marco L (2019). How Different Loading Sports and a 9-Month Plyometric Intervention Programme Affect Bone Turnover Markers During Adolescence: the PRO-BONE Study. the 9th Conference of Biochemistry and Physiology of Exercise.
Abstract:
How Different Loading Sports and a 9-Month Plyometric Intervention Programme Affect Bone Turnover Markers During Adolescence: the PRO-BONE Study
Abstract.
Vlachopoulos D, Barker AR, Williams CA, Gracia-Marco L (2019). How Different Loading Sports and a 9-Month Plyometric Intervention Programme Affect Bone Turnover Markers During Adolescence: the PRO-BONE Study. Conference of Biochemistry and Physiology of Exercise.
Farr C, Middlebrooke AR, Armstrong N, Barker AR, Fulford J, Mawson DM, McManus AM (2019). Objectively Measured Aerobic Fitness is Not Related to Vascular Health Outcomes and Cardiovascular Disease Risk in 9-10 Year Old Children.
JOURNAL OF SPORTS SCIENCE AND MEDICINE,
18(3), 513-522.
Author URL.
Denford S, Mackintosh K, McNarry M, Barker A, Williams C, Group AYU (2019). P377 Attitudes and experiences of physical activity among an international sample of people with cystic fibrosis and their support teams. Journal of Cystic Fibrosis, 18
Williams C, Tomlinson O, Withers N, Oades P, Barker A (2019). P383 Sex and age differences in aerobic fitness in people with cystic fibrosis. Journal of Cystic Fibrosis, 18, S166-S166.
Agbaje AO, Haapala EA, Lintu N, Viitasalo A, Barker AR, Takken T, Tompuri T, Lindi V, Lakka TA (2019). Peak oxygen uptake cut-points to identify children at increased cardiometabolic risk - the PANIC Study.
Scand J Med Sci Sports,
29(1), 16-24.
Abstract:
Peak oxygen uptake cut-points to identify children at increased cardiometabolic risk - the PANIC Study.
We aimed to develop cut-points for directly measured peak oxygen uptake (. V ˙ O 2 peak. ) to identify boys and girls at increased cardiometabolic risk using different scaling methods to control for body size and composition. Altogether 352 children (186 boys, 166 girls) aged 9-11 years were included in the analyses. We measured V̇O2peak directly during a maximal cycle ergometer exercise test and lean body mass (LM) by bioelectrical impedance. We computed a sex- and age-specific cardiometabolic risk score (CRS) by summing important cardiometabolic risk factors and defined increased cardiometabolic risk as >1 standard deviation above the mean of CRS. Receiver operating characteristics curves were used to detect V̇O2peak cut-points for increased cardiometabolic risk. Boys with V̇O2peak
Abstract.
Author URL.
Williams CAP, Malik A, Barker A, Weston K (2019). Perceptual and Cardiorespiratory Responses to High-Intensity Interval Exercise in Adolescents: Does Work Intensity Matter?. Journal of Sports Science and Medicine
Williams CA, Barker AR, Tomlinson OW (2019). Prediction of peak oxygen uptake using the modified shuttle test - Methodological concerns and implications for clinical practice.
Pediatr Pulmonol,
54(8), 1104-1105.
Author URL.
Denford S, Mackintosh KA, McNarry MA, Barker AR, Williams CA (2019). Promotion of physical activity for adolescents with cystic fibrosis: a qualitative study of UK multi-disciplinary cystic fibrosis teams. Physiotherapy
Kranen SH, Bond B, Williams CA, Barker AR (2019). Reliability of low-flow vasoreactivity in the brachial artery of adolescents.
Journal of Clinical Ultrasound,
47(3), 133-138.
Abstract:
Reliability of low-flow vasoreactivity in the brachial artery of adolescents
Purpose: Macrovascular endothelial function is commonly assessed using flow-mediated dilation (FMD) and is nitric oxide (NO) dependent. However, the vasoreactivity to low flow during the FMD protocol may complement FMD interpretation. This study aimed to investigate in adolescents: (1) the day-to-day reliability of low-flow-mediated constriction (L-FMC) and composite vessel reactivity (CVR); and (2) the relationship between L-FMC and FMD. Methods: a retrospective analysis of data on 27 adolescents (14.3 ± 0.6 year, 12 males) was performed. Participants had two repeat measures, on separate days, of macrovascular function using high-resolution ultrasound for assessment of L-FMC, FMD, and CVR. Results: on average, the L-FMC response was vasoconstriction on both days (−0.59 ± 2.22% and −0.16 ± 1.50%, respectively). In contrast, an inconsistent response to low flow (vasoconstriction, dilation, or no change) was observed on an individual level. Cohen's Kappa revealed poor agreement for classifying the L-FMC measurement between visits (k = 0.04, P >.05). Assessment of the actual vessel diameter was robust with a coefficient of variation of 1.7% (baseline and peak) and 2.7% (low-flow). The between-day correlation coefficient between measures was r =.18, r =.96 and r =.52 for L-FMC, FMD, and CVR, respectively. No significant correlation between FMD and L-FMC was observed for either visit (r = −.06 and r = −.07, respectively; P >.05). Conclusion: in adolescents, the low-flow vasoreactivity is inconsistent between days. Whereas the actual vessel diameter is reproducible, the measurement of L-FMC and CVR has poor between-day reliability compared to FMD. Finally, L-FMC, and FMD are not significantly correlated.
Abstract.
Bland C (2019). Sex Differences in Parameters of Cardiopulmonary Fitness and their Relationship to Clinical Outcomes in Young People with Cystic Fibrosis.
Abstract:
Sex Differences in Parameters of Cardiopulmonary Fitness and their Relationship to Clinical Outcomes in Young People with Cystic Fibrosis
Background: Females with cystic fibrosis have higher mortality rates than their male counterparts. Pulmonary function defined as forced expiratory volume in 1 s (FEV1) is a predictor of mortality. However, when pulmonary function is accounted for, females still have a higher mortality rate than males. Independent of lung function, peak oxygen uptake (VO2peak) is a significant predictor of mortality, with higher values of VO2peak relating to a lower risk of mortality. In healthy children, VO2peak is significantly different between sexes, however it has yet to be determined whether sex differences in VO2peak occur in CF. Aim: to identify sex differences in exercise capacity in young people with CF, when appropriately scaled for different body size variables and adjusted for key clinical parameters such as lung function and nutritional and maturity status. Methods: 52 young people (29 males and 23 females) aged 8 – 25 y with CF underwent a ramp cycle test to exhaustion. 47 completed an additional supramaximal cycle test to exhaustion at 110 % of ramp test peak power to verify that a true VO2max was obtained. VO2peak was scaled allometrically and using the ratio standard method. ANCOVAs were utilised to remove the influence of clinical parameters. Results: VO2peak was significantly lower in females than males for absolute VO2peak (p < 0.001, 1.41 ± 0.38 L∙min-1 and 2.17 ± 0.82 L∙min-1, respectively), VO2peak/BM*β (p < 0.001, 53.28 ± 10.93 mL·kg*0.82·min-1 and 73.04 ± 19.57 mL·kg*0.82·min-1, respectively), VO2peak/BSA*β (p < 0.001, 814.58 ± 159.05 mL·m2(*1.29)·min-1 and 1108.06 ± 296.24 mL·m2(*1.29)·min-1, respectively), and VO2peak/Stature*β (p
Abstract.
Koep J, Barker A, Bond B, Coombes J, Bailey T (2019). Shear stress and cerebrovascular function during acute isometric exercise: the role of exercise intensity and aging. Journal of Science and Medicine in Sport, 22
Mann RH, Williams CA, Clift BC, Barker AR (2019). The Validation of Session Rating of Perceived Exertion for Quantifying Internal Training Load in Adolescent Distance Runners.
Int J Sports Physiol Perform,
14(3), 354-359.
Abstract:
The Validation of Session Rating of Perceived Exertion for Quantifying Internal Training Load in Adolescent Distance Runners.
PURPOSE: to investigate the effect of measurement timing and concurrent validity of session and differential ratings of perceived exertion (sRPE and dRPE, respectively) as measures of internal training load in adolescent distance runners. METHODS: a total of 15 adolescent distance runners (15.2 [1.6] y) performed a 2-part incremental treadmill test for the assessment of maximal oxygen uptake, heart rate (HR), and blood lactate responses. Participants were familiarized with RPE and dRPE during the treadmill test using the Foster modified CR-10 Borg scale. Subsequently, each participant completed a regular 2-wk mesocycle of training. Participants wore an HR monitor for each exercise session and recorded their training in a logbook, including sRPE, dRPE leg exertion (dRPE-L), and breathlessness (dRPE-B) following session completion (0 min), 15 min postsession, and 30 min postsession. RESULTS: sRPE, dRPE-L, and dRPE-B scores were all most likely lower when reported 30 min postsession compared with scores 0 min postsession (%change, ±90% confidence limits; sRPE -26.5%, ±5.5%; dRPE-L -20.5%, ±5.6%; dRPE-B -38.9%, ±7.4%). sRPE, dRPE-L, and dRPE-B all maintained their largest correlations (r = .74-.89) when reported at session completion (0 min) in comparison with each of the HR-based criteria measures. CONCLUSION: sRPE, whether reported 0, 15, or 30 min postsession, provides a valid measure of internal training load in adolescent distance runners. In addition, dRPE-L and dRPE-B can be used in conjunction with sRPE across all time points (0, 15, and 30 min) to discriminate between central and peripheral exertion.
Abstract.
Author URL.
Cockcroft EJ, Bond B, Williams CA, Harris S, Jackman SR, Armstrong N, Barker AR (2019). The effects of two weeks high-intensity interval training on fasting glucose, glucose tolerance and insulin resistance in adolescent boys: a pilot study.
BMC Sports Science, Medicine and Rehabilitation,
11(1).
Abstract:
The effects of two weeks high-intensity interval training on fasting glucose, glucose tolerance and insulin resistance in adolescent boys: a pilot study
Abstract
. Background
. Current evidence of metabolic health benefits of high-intensity interval training (HIIT) are limited to longer training periods or conducted in overweight youth. This study assessed 1) fasting and postprandial insulin and glucose before and after 2 weeks of HIIT in healthy adolescent boys, and 2) the relationship between pre intervention health outcomes and the effects of the HIIT intervention.
.
. Methods
. Seven healthy boys (age:14.3 ± 0.3 y, BMI: 21.6 ± 2.6, 3 participants classified as overweight) completed 6 sessions of HIIT over 2 weeks. Insulin resistance (IR) and blood glucose and insulin responses to a Mixed Meal Tolerance Test (MMTT) were assessed before (PRE), 20 h and 70 h after (POST) the final HIIT session.
.
. Results
. Two weeks of HIIT had no effect on fasting plasma glucose, insulin or IR at 20 h and 70 h POST HIIT, nor insulin and glucose response to MMTT (all P > 0.05). There was a strong negative correlation between PRE training IR and change in IR after HIIT (r = − 0.96, P < 0.05).
.
. Conclusion
. Two weeks of HIIT did not elicit improvements to fasting or postprandial glucose or insulin health outcomes in a group of adolescent boys. However the negative correlation between PRE IR and improvements after HIIT suggest that interventions of this type may be effective in adolescents with raised baseline IR.
.
Abstract.
Cockcroft E, Bond B, Williams CA, Harris S, Jackman SR, Armstrong N, Barker AR (2019). The effects of two weeks high-intensity interval training on fasting glucose, glucose tolerance and insulin resistance in adolescent boys; a pilot study.
Koep J (2019). The influence of sugar sweetened beverage consumption on cerebrovascular function and postprandial health in adolescents.
Abstract:
The influence of sugar sweetened beverage consumption on cerebrovascular function and postprandial health in adolescents
Cardiovascular diseases (CVD) are the leading cause of non-communicable diseases worldwide, with the underlying atherosclerotic process originating in youth. Children and adolescents with CVD risk factors have impaired endothelial function, which is implicated in the process of atherosclerosis. Habitual sugar sweetened beverage (SSB) consumption is associated with the progression of CVD risk factors in youth, and adolescents consume the highest quantities of SSBs. Acute SSB consumption results in vascular dysfunction in adults, though the effects in youth are unknown. It is thought that exposure to CVD risk factors in youth may impair cerebrovascular reactivity (CVR), possibly having implications for future CVD risk. It is also unknown whether the types of sugar in SSBs have different consequences on vascular function. This thesis aimed to investigate the effect of sugar moiety on cerebrovascular function in adolescents, following consumption of a sugary drink and subsequent meal. Data on the reliability of CVR in a paediatric population was needed to first establish if this was a reliable measure of endothelial function. The purpose of this thesis was to: 1) examine the within and between-day reliability of a breath-hold protocol to assess CVR in adolescents. 2) examine the acute effect of sugar moiety (fructose, sucrose, glucose) on CVR and putative blood outcomes, and 3) examine the effects of SSB consumption on postprandial health in adolescents. Chapter 3 examined the reliability of a breath-hold protocol to assess CVR in youth, determined via transcranial Doppler ultrasonography of the middle cerebral artery (MCA). CVR was calculated as the percentage increase in MCAv mean following three breath-hold attempts. This outcome yielded acceptable levels of within and between-day reliability for use in multiple visit experiments to assess CVR in adolescents. Chapter 4 investigated the effect of sugar moiety on cerebrovascular function, measured through breath-hold induced CVR, in adolescents following SSB consumption and a subsequent challenge meal. This study found that the glucose and sucrose drinks resulted in elevated blood glucose levels compared to fructose and water. With consumption of fructose, elevations in uric acid were present, however the sugar moieties all presented similar increases in TAG concentrations following meal consumption. Despite these different metabolic responses, no significant impairments in CVR were present following the drink or challenge meal.
This thesis demonstrated that consumption of SSBs led to increases in glucose and uric acid concentrations, which have previously been shown to be atherogenic. This thesis also provided data on the reliability of CVR as a non-invasive and easy to administer tool for measurement of endothelial function in youth. This is the first study to demonstrate that breath-hold induced CVR can be reliably measured in youth, as a practical, affordable and non-invasive method. These findings provide valuable data that will inform the implementation and analysis of a breath-hold protocol for reliable CVR assessment in youth in future research. Having established that CVR was reliable within and between-day, it was not possible to determine if it was sensitive to change, with no effects seen on CVR following acute SSB consumption. To build on these findings, future research should explore the acute and chronic effects of SSB consumption, with consideration of measuring a range of different vascular outcomes such as changes in peripheral microvascular and macrovascular functions. As this thesis did not include another measure of peripheral endothelial function, it is not certain whether endothelial function was impaired, or if CVR was not sensitive to change in the present study. In order to determine if CVR is sensitive to change, future investigation is needed with established measures of peripheral endothelial function (i.e. flow mediated dilation) alongside measures of CVR.
Abstract.
Sansum KM, Weston ME, Bond B, Cockcroft EJ, O'Connor A, Tomlinson OW, Williams CA, Barker AR (2019). Validity of the Supramaximal Test to Verify Maximal Oxygen Uptake in Children and Adolescents.
Pediatr Exerc Sci,
31(2), 213-222.
Abstract:
Validity of the Supramaximal Test to Verify Maximal Oxygen Uptake in Children and Adolescents.
Purpose: This study had 2 objectives: (1) to examine whether the validity of the supramaximal verification test for maximal oxygen uptake ( V˙O2max ) differs in children and adolescents when stratified for sex, body mass, and cardiorespiratory fitness and (2) to assess sensitivity and specificity of primary and secondary objective criteria from the incremental test to verify V˙O2max. Methods: in total, 128 children and adolescents (76 male and 52 females; age: 9.3-17.4 y) performed a ramp-incremental test to exhaustion on a cycle ergometer followed by a supramaximal test to verify V˙O2max. Results: Supramaximal tests verified V˙O2max in 88% of participants. Group incremental test peak V˙O2 was greater than the supramaximal test (2.27 [0.65] L·min-1 and 2.17 [0.63] L·min-1; P
Abstract.
Author URL.
Tomlinson OW, Barker AR, Trott J, Withers NJ, Oades PJ, Williams CA (2019). WS02-3-1 Validity of prediction equations for evaluating aerobic fitness in cystic fibrosis. Journal of Cystic Fibrosis, 18, S3-S3.
2018
Vlachopoulos D, Barker AR, Ubago-Guisado E, Williams CA, Gracia-Marco L (2018). A 9-Month Jumping Intervention to Improve Bone Geometry in Adolescent Male Athletes.
Med Sci Sports Exerc,
50(12), 2544-2554.
Abstract:
A 9-Month Jumping Intervention to Improve Bone Geometry in Adolescent Male Athletes.
PURPOSE: Sports have different effects on bone development and effective interventions to improve bone health of adolescent athletes are needed. The purpose of the study was to investigate the effect of a 9-month jumping intervention on bone geometry and metabolism in adolescent male athletes. METHODS: Ninety-three adolescent (14.1 yr old) male swimmers (SWI), footballers (FOO), and cyclists (CYC) were randomized to intervention and sport (INT-SWI = 19, INT-FOO = 15, and INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, and CON-CYC = 12) groups. Cross-sectional area, cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck were assessed using hip structural analysis and trabecular texture of the lumbar spine using trabecular bone score. Bone mineral content (BMC) at femoral neck and lumbar spine was assessed using dual-energy x-ray absorptiometry. Serum N-terminal propeptide of procollagen type I, isomer of the carboxy-terminal telopeptide of type 1 collagen, total serum calcium, and 25-hydroxyvitamin D were analyzed. RESULTS: INT-CYC acquired significantly higher lumbar spine BMC (4.6%) and femoral neck BMC (9.8%) than CON-CYC. INT-CYC acquired significantly higher cross-sectional area (11.0%), CSMI (10.1%), and trabecular bone score (4.4%) than CON-CYC. INT-SWI acquired significantly higher femoral neck BMC (6.0%) and CSMI (10.9%) than CON-SWI. There were no significant differences between INT-FOO and CON-FOO in any bone outcomes. N-terminal propeptide of procollagen type I significantly decreased in CON-SWI, INT-FOO, CON-FOO, and CON-CYC. Carboxy-terminal telopeptide of type 1 collagen significantly decreased in CON-SWI and CON-CYC. The 25-hydroxyvitamin D significantly increased in INT-CYC, CON-CYC, INT-FOO, and CON-FOO. CONCLUSIONS: a 9-month jumping intervention improved bone outcomes in adolescent swimmers and cyclists, but not in footballers. This intervention might be used by sports clubs to improve bone health of adolescent athletes.
Abstract.
Author URL.
Vlachopoulos D, Barker AR, Ubago-Guisado E, Williams CA, Gracia-Marco L (2018). A 9-month Jumping Intervention to Improve Bone Acquisition in Adolescent Male Athletes. Medicine & Science in Sports & Exercise, 50(5S).
Vlachopoulos D, Barker AR, Ubago-Guisado E, Williams CA, Gracia-Marco L (2018). A 9-month Jumping Intervention to Improve Bone Acquisition in Adolescent Male Athletes: the PRO-BONE Study.
Author URL.
Cockcroft EJ, Williams CA, Jackman SR, Bassi S, Armstrong N, Barker AR (2018). A single bout of high-intensity interval exercise and work-matched moderate-intensity exercise has minimal effect on glucose tolerance and insulin sensitivity in 7- to 10-year-old boys.
Journal of Sports Sciences,
36(2), 149-155.
Abstract:
A single bout of high-intensity interval exercise and work-matched moderate-intensity exercise has minimal effect on glucose tolerance and insulin sensitivity in 7- to 10-year-old boys
The purpose of this study was to assess the acute effect of high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on glucose tolerance, insulin sensitivity and fat oxidation in young boys. Eleven boys (8.8 ± 0.8 y) completed three conditions: 1) HIIE; 2) work-matched MIE; and 3) rest (CON) followed by an oral glucose tolerance test (OGTT) to determine glucose tolerance and insulin sensitivity (Cederholm index). Fat oxidation was measured following the OGTT using indirect calorimetry. There was no effect for condition on plasma [glucose] and [insulin] area under the curve (AUC) responses following the OGTT (P > 0.09). However, there was a “trend” for a condition effect for insulin sensitivity with a small increase after HIIE (P = 0.04, ES = 0.28, 9.7%) and MIE (P = 0.07, ES = 0.21, 6.5%) compared to CON. There was an increase in fat oxidation AUC following HIIE (P = 0.008, ES = 0.79, 38.9%) compared to CON, but with no differences between MIE and CON and HIIE and MIE (P > 0.13). In conclusion, 7- to 10-year-old boys may have limited scope to improve insulin sensitivity and glucose tolerance after a single bout of HIIE and MIE. However, fat oxidation is augmented after HIIE but not MIE.
Abstract.
Ferri-Morales A, Nascimento-Ferreira MV, Vlachopoulos D, Ubago-Guisado E, Torres-Costoso A, De Moraes ACF, Barker AR, Moreno LA, Martínez-Vizcaino V, Gracia-Marco L, et al (2018). Agreement Between Standard Body Composition Methods to Estimate Percentage of Body Fat in Young Male Athletes.
Pediatr Exerc Sci,
30(3), 402-410.
Abstract:
Agreement Between Standard Body Composition Methods to Estimate Percentage of Body Fat in Young Male Athletes.
PURPOSE: to examine the intermethods agreement of dual-energy X-ray absorptiometry (DXA) and foot-to-foot bioelectrical impedance analysis (BIA) to assess the percentage of body fat (%BF) in young male athletes using air-displacement plethysmography (ADP) as the reference method. METHODS: Standard measurement protocols were carried out in 104 athletes (40 swimmers, 37 footballers, and 27 cyclists, aged 12-14 y). RESULTS: Age-adjusted %BF ADP and %BF BIA were significantly higher in swimmers than footballers. ADP correlates better with DXA than with BIA (r = .84 vs r = .60, P
Abstract.
Author URL.
Tomlinson OW, Barker AR, Chubbock LV, Stevens D, Saynor ZL, Oades PJ, Williams CA (2018). Analysis of oxygen uptake efficiency parameters in young people with cystic fibrosis. European Journal of Applied Physiology, 118(10), 2055-2063.
Oliveira RS, Barker AR, Williams CA (2018). Cardiac Autonomic Function, Cardiovascular Risk and Physical Activity in Adolescents.
Int J Sports Med,
39(2), 89-96.
Abstract:
Cardiac Autonomic Function, Cardiovascular Risk and Physical Activity in Adolescents.
The aims of this study were to investigate in adolescents: 1) the relationships of physical activity (PA) and cardiorespiratory fitness (CRF) to traditional CVD risk factors, rest and recovery autonomic function; and 2) whether autonomic function strengthens the associations between PA, CRF and CVD risk. Fifty-four (22 girls) adolescents had traditional CVD risk factors, rest and recovery autonomic function evaluated. CRF was measured using a steep ramp cycle test and PA was assessed with accelerometers. Resting HRV (and RMSSD30) and heart rate recovery (T30, HHRτ) were used. Clustered traditional (CVDRtrad) and autonomic (CVDRauto) risk scores were created and added to form a composite clustered CVD risk score (CVDRcom). PA and CRF were significantly and negatively associated with traditional CVD risk factors. Moderate (MPA) and vigorous (VPA) were positively related to resting RMSSD, and negatively related to T30 and HHRτ (all P
Abstract.
Author URL.
Barker A, Gracia-Marco L, Vlachopoulos D, Williams C (2018). Growth, Maturation, and Physical Fitness. In Norton K, Eston R (Eds.) Kinanthropometry and Exercise Physiology, London: Routledge.
Vlachopoulos D, Barker A, Ubago-Guisado E, Williams C, Gracia-Marco L (2018). HOW DIFFERENT LOADING SPORTS AFFECT BONE DEVELOPMENT DURING ADOLESCENCE AND HOW TO IMPROVE IT? THE PRO-BONE STUDY FINDINGS.
Author URL.
Oliveira R, Barker AR, Debras F, O'Doherty A, Williams CA (2018). Mechanisms of blood pressure control following acute exercise in adolescents: Effects of exercise intensity on haemodynamics and baroreflex sensitivity.
Exp Physiol,
103(8), 1056-1066.
Abstract:
Mechanisms of blood pressure control following acute exercise in adolescents: Effects of exercise intensity on haemodynamics and baroreflex sensitivity.
NEW FINDINGS: What is the central question of this study? What are the autonomic and vascular components of the baroreflex during hypotension following different exercise intensities in adolescents? What is the main finding and its importance? Hypotension after high-intensity exercise lasted 60 min, whereas following moderate-intensity exercise, blood pressure was restored after 20 min. Stroke volume and peripheral resistance responses were different between intensities. Post both exercise intensities, baroreflex sensitivity was lowered mainly due to the autonomic component, which returned to baseline 60 min post-exercise. The different haemodynamic stimuli indicate potential differences in cardiovascular health benefits of exercise intensity in healthy adolescents. ABSTRACT: This work aimed to investigate the time course of changes in baroreflex sensitivity (BRS) and its vascular and autonomic components after different exercise intensities in adolescents. Thirteen male adolescents (age 13.9 ± 0.5 years) completed on separate days in a counterbalanced order (1) high-intensity interval exercise (HIIE): 8 × 1 min running at 90% of maximal aerobic speed with 75 s of active recovery; (2) moderate-intensity interval exercise (MIIE): 10-12 bouts of 1 min running at 90% of gas exchange threshold with 75 s of active recovery; and (3) resting as a control. Supine heart rate and blood pressure were monitored continuously at baseline, and 5 and 60 min following the conditions. A cross-spectral method (low frequency gain; LFgain ) was used to determine BRS gain. Arterial compliance (AC) was assessed as the BRS vascular component. LFgain /AC was used as the autonomic component. LFgain decreased 5 min post-exercise bouts (HIIE P
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Author URL.
Malik AA, Williams CA, Weston KL, Barker AR (2018). Perceptual Responses to High- and Moderate-Intensity Interval Exercise in Adolescents.
Med Sci Sports Exerc,
50(5), 1021-1030.
Abstract:
Perceptual Responses to High- and Moderate-Intensity Interval Exercise in Adolescents.
PURPOSE: Continuous high-intensity exercise is proposed to evoke unpleasant sensations as predicted by the dual-mode theory and may negatively impact on future exercise adherence. Previous studies support unpleasant sensations in affective responses during continuous high-intensity exercise, but the affect experience during high-intensity interval exercise (HIIE) involving brief bursts of high-intensity exercise separated by low-intensity activity is poorly understood in adolescents. We examined the acute affective, enjoyment, and perceived exertion responses to HIIE compared with moderate-intensity interval exercise (MIIE) in adolescents. METHODS: Thirteen adolescent boys (mean ± SD: age, 14.0 ± 0.5 yr) performed two counterbalanced exercise conditions: 1) HIIE: 8 × 1-min work intervals at 90% maximal aerobic speed; and 2) MIIE: between 9 and 12 × 1-min work intervals at 90% ventilatory threshold where the number of intervals performed were distance-matched to HIIE. HIIE and MIIE work intervals were interspersed with 75 s active recovery at 4 km·h. Affect, enjoyment, and RPE were recorded before, during, and after exercise. RESULTS: Affect responses declined in both conditions but the fall was greater in HIIE than MIIE (P < 0.025, effect size [ES], 0.64 to 0.81). Affect remained positive at the end-work interval for both conditions (MIIE, 2.62 ± 1.50; HIIE, 1.15 ± 2.08 on feeling scale). No enjoyment differences were evident during HIIE and MIIE (P = 0.32), but HIIE elicited greater postexercise enjoyment compared with MIIE (P = 0.01, ES = 0.47). RPE was significantly higher during HIIE than MIIE across all work intervals (all P < 0.03, ES > 0.64). CONCLUSIONS: Despite elevated RPE, HIIE did not elicit prominent unpleasant feelings as predicted by the dual-mode theory and was associated with greater postexercise enjoyment responses than MIIE. This study demonstrates the feasibility of the application of HIIE as an alternative form of physical activity in adolescents.
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Author URL.
Malik AA, Williams CA, Weston KL, Barker AR (2018). Perceptual and prefrontal cortex haemodynamic responses to high-intensity interval exercise with decreasing and increasing work-intensity in adolescents.
Int J Psychophysiol,
133, 140-148.
Abstract:
Perceptual and prefrontal cortex haemodynamic responses to high-intensity interval exercise with decreasing and increasing work-intensity in adolescents.
OBJECTIVES: Affect experienced during high-intensity interval exercise (HIIE) is dependent on work-intensity, but the influence of increasing (low-to-high (L-H)) or decreasing (high-to-low (H-L)) work-intensity during HIIE remains unclear in adolescents. The role of prefrontal cortex haemodynamics in mediating changes in affect during HIIE also remains unexplored in adolescents. We examined affect, enjoyment and cerebral haemodynamic responses to HIIE with increasing or decreasing work intensities in adolescents. METHODS: Participants (N = 16; 8 boys; age 12.5 ± 0.8 years) performed, on separate days, HIIE cycling consisting of 8 × 1-min work-intervals at 100%-to-70% (HIIEH-L), 70%-to-100% (HIIEL-H) or 85% (HIIECON) peak power separated by 75 s recovery. Affect, enjoyment and cerebral haemodynamics (oxygenation (∆O2Hb), deoxygenation (∆HHb) and tissue oxygenation index (TOI)) were recorded before, during, and after all conditions. RESULTS: Affect and enjoyment were lower during HIIEH-L compared to HIIEL-H and HIIECON at work-intervals 1 to 3 (all P 0.83) but were greater during HIIEH-L than HIIEL-H and HIIECON at work-interval 8 (all P 0.83). ∆O2Hb was similar across conditions (P = 0.87) but TOI and ∆HHb were significantly greater and lower, respectively during HIIEH-L compared to HIIEL-H and HIIECON at work-interval 8 (all P 0.40). Affect was correlated with TOI (all r > 0.92) and ∆HHb (all r > -0.73) across conditions. CONCLUSIONS: HIIEH-L offers advancement to the HIIECON and HIIEL-H which bring significant greater affect and enjoyment towards the end HIIE work-interval, implicating the feasibility and adoption of this protocol for health promotion in youth. Also, changes in prefrontal cortex haemodynamics are associated with the affect during HIIE.
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Author URL.
Barker AR, Gracia-Marco L, Ruiz JR, Castillo MJ, Aparicio-Ugarriza R, González-Gross M, Kafatos A, Androutsos O, Polito A, Molnar D, et al (2018). Physical activity, sedentary time, TV viewing, physical fitness and cardiovascular disease risk in adolescents: the HELENA study.
Int J Cardiol,
254, 303-309.
Abstract:
Physical activity, sedentary time, TV viewing, physical fitness and cardiovascular disease risk in adolescents: the HELENA study.
BACKGROUND: to examine the independent associations between physical activity (PA) intensities, sedentary time (ST), TV viewing, cardiorespiratory fitness (CRF) and muscular fitness (MF) with cardiovascular disease (CVD) risk in youth. METHODS: a cross-sectional study on 534 European adolescents (252 males, 282 females, 12.5-17.5years). Minutes per day of light (LPA), moderate (MPA) and vigorous (VPA) PA and total ST were measured using accelerometers. TV viewing time was measured using a questionnaire. CRF and MF were measured using the 20m shuttle run test and a hand dynamometer respectively. CVD outcomes included markers of body composition (body mass index (BMI), waist circumference (WC), WC/height (Ht) and sum of skinfolds (SumSF)), blood pressure, blood lipids and insulin resistance (HOMA-IR). Clustered CVD risk was calculated using SumSF, HOMA-IR, blood lipids and blood pressure. RESULTS: LPA had a significant positive independent relationship with all body composition outcomes (P0.16). TV viewing had a significant positive independent relationship with HOMA-IR (P
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Tomlinson OW, Shelley J, Denford S, Barker AR, Oades PJ, Williams CA (2018). Promotion of exercise in the management of cystic fibrosis - summary of national meetings.
European Journal for Person Centered Healthcare,
6(2), 196-196.
Abstract:
Promotion of exercise in the management of cystic fibrosis - summary of national meetings
Rationale, aims and objectives: Physical activity (PA) and exercise are important in maintaining and improving health and wellbeing in people with cystic fibrosis (CF) and measures of exercise capacity are useful outcomes in monitoring disease progression. The roles and responsibilities of CF multi-disciplinary team (MDT) members in supporting PA and exercise have yet to be fully defined. This communication reports on national meetings of CF MDT staff whose interest is to improve and standardise person-centered exercise provision and testing as part of routine CF care. We also introduce the role of the physiotherapy technician in supporting PA interventions.Meetings: the two meetings covered a range of presentations, discussions and workshops, focusing on the role of exercise and PA in CF management. Forty people from 15 NHS Hospital Trusts and 3 universities were asked to provide feedback via a questionnaire.Results: the common roles and responsibilities of clinical staff involved in exercise testing and prescription are described, with a wide range of duties identified. In addition, physiotherapists were reported as the main MDT member responsible for exercise provision. The majority of teams reported discussing exercise at every clinical visit (57%) and felt confident in discussing exercise with patients (67%).Conclusions: While this report highlights the current provision of exercise in CF MDTs, it also provides insight into the resources MDTs may require in order to enhance the profile of exercise within CF services, including enhanced training, guidelines and standardised clinical roles.
Abstract.
Oliveira RS, Barker AR, Debras F, O'Doherty A, Williams CA (2018). Reliability of autonomic and vascular components of baroreflex sensitivity in adolescents.
Clinical Physiology and Functional Imaging,
38(6), 986-993.
Abstract:
Reliability of autonomic and vascular components of baroreflex sensitivity in adolescents
Improvements in the autonomic and vascular systems are implicated in cardiovascular disease risk reduction. Baroreflex sensitivity (BRS) is composed of vascular and autonomic components. This study aimed to investigate between- and within-day reliability of BRS and its autonomic and vascular determinants in adolescents. Thirteen male adolescents (14·1 ± 0·5 y) participated in this study. For between-day reliability, participants completed four experimental visits separated by a minimum of 48-h. For within-day reliability, participants repeated BRS assessments three times in the morning with one hour between the measures. BRS was evaluated using the cross-spectral gain (LFgain) between blood pressure and heart rate interval. BRS was further divided into: 1) vascular component using arterial compliance (AC); and 2) autonomic component measured as LFgain divided by AC (LFgain/AC). LFgain, AC and LFgain/AC presented between-day coefficient of variation (CV) of 20%, 17%, and 20%, respectively. Similarly, variables associated with blood pressure control, such as cardiac output, mean arterial pressure, heart rate and total peripheral resistance, presented CVs ranging from 6% to 15%. Within-day reliability was poorer compared to between-day for LFgain (25%), AC (25%), and LFgain/AC (31%), as well as all hemodynamic variables (CVs from 11% to 22%, except heart rate with presented CV of 6%). This study indicates suitable between- and within-reliability of BRS and its autonomic and vascular determinants, as well as hemodynamic variables associated with BRS, in adolescents.
Abstract.
Vlachopoulos D, Barker AR, Ubago-Guisado E, Ortega FB, Krustrup P, Metcalf B, Castro Pinero J, Ruiz JR, Knapp KM, Williams CA, et al (2018). The effect of 12-month participation in osteogenic and non-osteogenic sports on bone development in adolescent male athletes. The PRO-BONE study.
J Sci Med Sport,
21(4), 404-409.
Abstract:
The effect of 12-month participation in osteogenic and non-osteogenic sports on bone development in adolescent male athletes. The PRO-BONE study.
OBJECTIVES: Research investigating the longitudinal effects of the most popular sports on bone development in adolescent males is scarce. The aim is to investigate the effect of 12-month participation in osteogenic and non-osteogenic sports on bone development. DESIGN: a 12-month study was conducted in adolescent males involved in football, swimming and cycling and compared with an active control group. METHODS: 116 adolescent males (13.1±0.1years at baseline): 37 footballers, 37 swimmers, 28 cyclists and 14 active controls were followed for 12 months. Bone mineral content (BMC) was measured by dual-energy X-ray absorptiometry, and bone stiffness was measured by quantitative ultrasound. Bone outcomes at 12 months were adjusted for baseline bone status, age, height, lean mass and moderate to vigorous physical activity. RESULTS: Footballers had higher improvement in adjusted BMC at the total body, total hip, shaft, Ward's triangle, legs and bone stiffness compared to cyclists (6.3-8.0%). Footballers had significantly higher adjusted BMC at total body, shaft and legs compared to swimmers (5.4-5.6%). There was no significant difference between swimmers and cyclists for any bone outcomes. Swimming and cycling participation resulted in non-significant lower bone development at most sites of the skeleton compared to controls (-4.3 to -0.6%). CONCLUSIONS: Football participation induces significantly greater improvements in BMC and bone stiffness over 12 months compared to cycling and swimming. CLINICAL TRIAL REGISTRATION: ISRCTN17982776.
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Vlachopoulos D, Barker AR, Ubago-Guisado E, Williams CA, Gracia-Marco L (2018). The effect of a high-impact jumping intervention on bone mass, bone stiffness and fitness parameters in adolescent athletes.
Arch Osteoporos,
13(1).
Abstract:
The effect of a high-impact jumping intervention on bone mass, bone stiffness and fitness parameters in adolescent athletes.
UNLABELLED: This study demonstrates that a 9-month jumping intervention can improve bone mass gains and physical fitness performance in adolescent males participating in non-osteogenic sports, such as swimming and cycling. PURPOSE: to examine the effect of a jumping intervention on bone mass, bone stiffness and fitness parameters in adolescents involved in different sports. METHODS: Ninety-three adolescent male swimmers (SWI), footballers (FOO) and cyclists (CYC) were randomised to intervention (INT) and sport (INT-SWI = 19, INT-FOO = 15, INT-CYC = 14) or sport only (CON-SWI = 18, CON-FOO = 15, CON-CYC = 12) groups. The 9-month jumping intervention consisted of 3 levels (12 weeks each) of 20 repetitions per set of counter movement jumps (CMJ) using adjustable weight vests (level 1 = 20 CMJ jumps/set, 0 kg, 3 sets/day, 3 times/week; level 2 = 20 CMJ jumps/set, 2 kg, 4 sets/day, 3 times/week; level 3 = 20 CMJ jumps/set, 5 kg, 4 sets/day, 4 times/week). Total body bone mineral content (BMC) at total body less head (TBLH) was measured using dual-energy X-ray absorptiometry and bone stiffness using quantitative ultrasound. Fitness was assessed using the 20-m shuttle run (20mSRT), CMJ and standing long jump (SLJ) tests. RESULTS: INT-SWI had significantly higher increase in BMC legs and bone stiffness compared to CON-SWI (4.2-12.7%). INT-CYC had significantly higher increase in BMC at TBLH and legs and bone stiffness compared to CON-CYC (5.0-12.3%). There were no significant differences between INT-FOO and CON-FOO in any bone outcomes (0.9-3.9%). The increase in CMJ performance was significantly higher in INT-SWI (3.1 cm) and INT-CYC (3.2 cm) compared to CON-SWI and CON-CYC groups, respectively. CONCLUSIONS: a 9-month jumping intervention can improve bone mass, bone stiffness and muscular fitness in adolescent males participating in non-osteogenic sports, such as swimming and cycling. CLINICAL TRIAL REGISTRATION: ISRCTN17982776.
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Williams CA, Tomlinson OW, Chubbock LV, Stevens D, Saynor ZL, Oades PJ, Barker AR (2018). The oxygen uptake efficiency slope is not a valid surrogate of aerobic fitness in cystic fibrosis.
Pediatr Pulmonol,
53(1), 36-42.
Abstract:
The oxygen uptake efficiency slope is not a valid surrogate of aerobic fitness in cystic fibrosis.
BACKGROUND: Maximal cardiopulmonary exercise testing is recommended on an annual basis for children with cystic fibrosis (CF), due to clinically useful prognostic information provided by maximal oxygen uptake (V̇O2max ). However, not all patients are able, or willing, to reach V̇O2max , and therefore submaximal alternatives are required. This study explored the validity of the oxygen uptake efficiency slope (OUES) as a submaximal measure of V̇O2max in children and adolescents with CF. METHODS: Data were collated from 72 cardiopulmonary exercise tests (36 CF, 36 controls), with OUES determined relative to maximal and submaximal parameters of exercise intensity, time, and individual metabolic thresholds. Pearson's correlation coefficients, independent t-tests, and factorial ANOVAs were used to determine validity. RESULTS: Significant (P 0.05). When split by V̇O2max tertiles, minimal significant differences were found between, and within, groups for OUES, indicating poor discrimination of V̇O2max. CONCLUSIONS: the OUES is not a valid (sub) maximal measure of V̇O2max in children and adolescents with mild-to-moderate CF. Clinicians should continue to use maximal markers (ie, V̇O2max ) of exercise capacity.
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Tomlinson OW, Barker AR, Chubbock LV, Stevens D, Saynor ZL, Oades PJ, Williams CA (2018). WS08.1 the utility of oxygen uptake efficiency as a marker of aerobic fitness in children with cystic fibrosis. Journal of Cystic Fibrosis, 17, S14-S14.
2017
Cockcroft EJ, Williams CA, Weaver H, O'Connor A, Jackman SR, Armstrong N, Barker AR (2017). Acute Exercise and Insulin Sensitivity in Boys: a Time-Course Study.
Int J Sports Med,
38(13), 967-974.
Abstract:
Acute Exercise and Insulin Sensitivity in Boys: a Time-Course Study.
This study examined the time course of adaptions in insulin sensitivity (IS) in adolescent boys after acute high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE). Eight boys (15.1±0.4 y) completed three 3-day experimental trials in a randomised order: 1) 8×1 min cycling at 90% peak power with 75 s recovery (HIIE); 2) cycling at 90% of gas exchange threshold for a duration to match work during HIIE (MIE); and 3) rest (CON). Plasma [glucose] and [insulin] were measured before (PRE-Ex), 24 and 48 h post (24 h-POST, 48 h-POST) in a fasted state, and 40 min (POST-Ex) and 24 h (24 h-POST) post in response to an oral glucose tolerance test (OGTT). IS was estimated using the Cederholm (OGTT) and HOMA (fasted) indices. There was no change to HOMA at 24 h or 48 h-POST (all P>0.05). IS from the OGTT was higher POST-EX for HIIE compared to CON (17.4%, P=0.010, ES=1.06), and a non-significant increase in IS after MIE compared to CON (9.0%, P=0.14, ES=0.59). At 24 h-POST, IS was higher following both HIIE and MIE compared to CON (HIIE: P=0.019, 13.2%, ES=0.88; MIE: 9.7%, P=0.024, ES=0.65). In conclusion, improvements to IS after a single bout of HIIE and MIE persist up to 24 h after exercise when assessed by OGTT.
Abstract.
Author URL.
Malik AA, Williams CA, Bond B, Weston KL, Barker AR (2017). Acute cardiorespiratory, perceptual and enjoyment responses to high-intensity interval exercise in adolescents. European Journal of Sport Science, 17(10), 1335-1342.
Dormehl SJ, Robertson SJ, Barker AR, Williams CA (2017). Confirming the Value of Swimming-Performance Models for Adolescents.
Int J Sports Physiol Perform,
12(9), 1177-1185.
Abstract:
Confirming the Value of Swimming-Performance Models for Adolescents.
PURPOSE: to evaluate the efficacy of existing performance models to assess the progression of male and female adolescent swimmers through a quantitative and qualitative mixed-methods approach. METHODS: Fourteen published models were tested using retrospective data from an independent sample of Dutch junior national-level swimmers from when they were 12-18 y of age (n = 13). The degree of association by Pearson correlations was compared between the calculated differences from the models and quadratic functions derived from the Dutch junior national qualifying times. Swimmers were grouped based on their differences from the models and compared with their swimming histories that were extracted from questionnaires and follow-up interviews. RESULTS: Correlations of the deviations from both the models and quadratic functions derived from the Dutch qualifying times were all significant except for the 100-m breaststroke and butterfly and the 200-m freestyle for females (P <. 05). In addition, the 100-m freestyle and backstroke for males and 200-m freestyle for males and females were almost directly proportional. In general, deviations from the models were accounted for by the swimmers' training histories. Higher levels of retrospective motivation appeared to be synonymous with higher-level career performance. CONCLUSION: This mixed-methods approach helped confirm the validity of the models that were found to be applicable to adolescent swimmers at all levels, allowing coaches to track performance and set goals. The value of the models in being able to account for the expected performance gains during adolescence enables quantification of peripheral factors that could affect performance.
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Cockcroft EJ, Moudiotis C, Kitchen J, Bond B, Williams CA, Barker AR (2017). High-intensity interval exercise and glycemic control in adolescents with type one diabetes mellitus: a case study.
Physiol Rep,
5(13).
Abstract:
High-intensity interval exercise and glycemic control in adolescents with type one diabetes mellitus: a case study.
Current physical activity guidelines for youth with type 1 diabetes (T1D) are poorly supported by empirical evidence and the optimal dose of physical activity to improve glycemic control is unknown. This case report documents the effect of acute high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on 24-h glycemic control in three adolescents with T1D using continuous glucose monitoring. Results highlight varied individual response to exercise across the participants. In two participants both MIE and HIIE resulted in a drop in blood glucose during exercise (-38 to -42% for MIE and -21-46% in HIIE) and in one participant both MIE and HIIE resulted in increased blood glucose (+19% and + 36%, respectively). Over the 24-h period average blood glucose was lower for all participants in the HIIE condition, and for two for the MIE condition, compared to no exercise. All three participants reported HIIE to be more enjoyable than MIE These data show both HIIE and MIE have the potential to improve short-term glycemic control in youth with T1D but HIIE was more enjoyable. Future work with a larger sample size is required to explore the potential for HIIE to improve health markers in youth with T1D.
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Oliveira RS, Barker AR, Wilkinson KM, Abbott RA, Williams CA (2017). Is cardiac autonomic function associated with cardiorespiratory fitness and physical activity in children and adolescents? a systematic review of cross-sectional studies.
Int J Cardiol,
236, 113-122.
Abstract:
Is cardiac autonomic function associated with cardiorespiratory fitness and physical activity in children and adolescents? a systematic review of cross-sectional studies.
BACKGROUND: Heart rate variability (HRV) is considered to explain improvements in cardiovascular health accrued by physical activity (PA) and cardiorespiratory fitness (CRF) over and above traditional cardiovascular risk factors. OBJECTIVE: to systematically address associations between HRV, PA and CRF in children and adolescents. DATA SOURCES: Medline, EMBASE, SportDISCUS and CINAHL Plus were searched on 5th September 2015 and updated on 4th August 2016. ELIGIBILITY CRITERIA: Observational studies comparing HRV in different groups of PA and CRF, and/or studies investigating associations between PA, CRF and HRV. Sports practices and PA intensities were also included. The square root of the mean of the sum of the squares of differences between adjacent RR intervals (RMSSD), the spectral density in the high (HF) and low (LF) frequency, and the LF/HF ratio were included. Risk of bias was assessed using the adapted Newcastle-Ottawa Scale (NOS). RESULTS: Heterogeneity exists in the assessment of the exposures and outcomes, and sample characteristics. Risk of bias (NOS) was observed in most of the studies. Studies with low risk of bias showed positive associations between moderate-to-vigorous PA and RMSSD. The evidence for the associations between PA and frequency indices is weak. Similarly, the evidence for the association between CRF and HRV is weak. CONCLUSIONS: Despite the heterogeneity in the studies, moderate-to-vigorous PA is positively associated with RMSSD, but less clear are the associations between CRF and HRV, as well as other PA intensities. Further research is needed to clarify the role of PA and CRF on HRV in children and adolescents.
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Vlachopoulos D, Barker AR, Ubago-Guisado E, Fatouros IG, Knapp KM, Williams CA, Gracia-Marco L (2017). Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: the PRO-BONE Study.
J Bone Miner Res,
32(11), 2269-2277.
Abstract:
Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: the PRO-BONE Study.
Adolescence is a crucial period for bone development, and exercise can enhance bone acquisition during this period of life. However, it is not known how the different loading sports practiced can affect bone acquisition in adolescent male athletes. Therefore, the purpose of the present study was to determine the 1-year longitudinal bone acquisition among adolescent males involved in osteogenic (football) and non-osteogenic (swimming and cycling) sports and to compare with active controls. A total of 116 adolescent males aged 12 to 14 years at baseline were followed for 1 year: 37 swimmers, 37 footballers, 28 cyclists, and 14 active controls. Bone mineral content (BMC) was assessed using dual-energy X-ray absorptiometry (DXA); cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and section modulus (Z) at the femoral neck was assessed using hip structural analysis (HSA); and bone texture of the lumbar spine was assessed using trabecular bone score (TBS). Serum N-terminal propeptide of procollagen type I (PINP), isomer of the Carboxi-terminal telopeptide of type 1 collagen (CTX-I), total serum calcium, and 25 hydroxyvitamin D [25(OH)D] were analyzed. Footballers had significantly higher adjusted BMC at the lumbar spine (7.0%) and femoral neck (5.0%) compared with cyclists, and significantly greater BMC at the lumbar spine (6.9%) compared with swimmers. Footballers presented significantly greater TBS (4.3%) compared with swimmers, and greater CSMI (10.2%), CSA (7.1%), Z (8.9%) and TBS (4.2%) compared with cyclists. No differences were noted between cyclists and swimmers, both groups had similar bone acquisition compared with controls. PINP was significantly higher in footballers and controls compared with cyclists and swimmers (3.3% to 6.0%), and 25(OH)D was significantly higher in footballers and cyclists compared with swimmers and controls (9.9% to 13.1%). These findings suggest that bone acquisition is higher in adolescent male footballers compared with swimmers and cyclists at the femoral neck and lumbar spine sites of the skeleton. © 2017 American Society for Bone and Mineral Research.
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Author URL.
Williams CA, Saynor ZL, Barker AR, Oades PJ, Tomlinson OW (2017). Measurement of V̇o2max in clinical groups is feasible and necessary.
J Appl Physiol (1985),
123(4).
Author URL.
Bond B, Weston KL, Williams CA, Barker AR (2017). Perspectives on high-intensity interval exercise for health promotion in children and adolescents.
Open Access J Sports Med,
8, 243-265.
Abstract:
Perspectives on high-intensity interval exercise for health promotion in children and adolescents.
Physical activity lowers future cardiovascular disease (CVD) risk; however, few children and adolescents achieve the recommended minimum amount of daily activity. Accordingly, there is virtue in identifying the efficacy of small volumes of high-intensity exercise for health benefits in children and adolescents for the primary prevention of CVD risk. The purpose of this narrative review is to provide a novel overview of the available literature concerning high-intensity interval-exercise (HIIE) interventions in children and adolescents. Specifically, the following areas are addressed: 1) outlining the health benefits observed following a single bout of HIIE, 2) reviewing the role of HIIE training in the management of pediatric obesity, and 3) discussing the effectiveness of school-based HIIE training. In total, 39 HIIE intervention studies were included in this review. Based upon the available data, a single bout of high-intensity exercise provides a potent stimulus for favorable, acute changes across a range of cardiometabolic outcomes that are often superior to a comparative bout of moderate-intensity exercise (14 studies reviewed). HIIE also promotes improvements in cardiorespiratory fitness and cardiometabolic health status in overweight and obese children and adolescents (10 studies reviewed) and when delivered in the school setting (15 studies reviewed). We thus conclude that high-intensity exercise is a feasible and potent method of improving a range of cardiometabolic outcomes in children and adolescents. However, further work is needed to optimize the delivery of HIIE interventions in terms of participant enjoyment and acceptability, to include a wider range of health outcomes, and to control for important confounding variables (eg, changes in diet and habitual physical activity). Finally, research into the application of HIIE training interventions to children and adolescents of different ages, sexes, pubertal status, and sociocultural backgrounds is required.
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Tomlinson OW, Barker AR, Oades PJ, Williams CA (2017). Scaling the Oxygen Uptake Efficiency Slope for Body Size in Cystic Fibrosis.
Med Sci Sports Exerc,
49(10), 1980-1986.
Abstract:
Scaling the Oxygen Uptake Efficiency Slope for Body Size in Cystic Fibrosis.
PURPOSE: the aim of this study was to describe the relationship between body size and oxygen uptake efficiency slope (OUES) in pediatric patients with cystic fibrosis (CF) and healthy controls (CON), to identify appropriate scaling procedures to adjust the influence of body size upon OUES. METHODS: the OUES was derived using maximal and submaximal points from cardiopulmonary exercise testing in 72 children (36 CF and 36 CON). OUES was subsequently scaled for stature, body mass (BM), and body surface area (BSA) using ratio-standard (Y/X) and allometric (Y/X) methods. Pearson's correlation coefficients were used to determine the relationship between body size and OUES. RESULTS: When scaled using the ratio-standard method, OUES had a significant positive relationship with stature (r = 0.54, P < 0.001) and BSA (r = 0.25, P = 0.031) and significant negative relationship with BM (r = -0.38, P = 0.016) in the CF group. Combined allometric exponents (b) for CF and CON were stature 3.00, BM 0.86, and BSA 1.40. A significant negative correlation was found between OUES and stature in the CF group when scaled allometrically (r = -0.37, P = 0.027). Nonsignificant (P > 0.05) correlations for the whole group were found between OUES and allometrically scaled BM (CF r = -0.25, CON, r = 0.15) and BSA (CF r = -0.27, CON r = 0.13). CONCLUSIONS: Only allometric scaling of either BM or BSA, and not ratio-standard scaling, successfully eliminates the influence of body size upon OUES. Therefore, this enables a more direct comparison of the OUES between patients with CF and healthy controls.
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Vlachopoulos D, Barker, Williams CA, Arngrímsson SA, Knapp KM, Metcalf B, Fatouros IG, Moreno LA, Gracia Marco (2017). The impact of sport participation on bone mass and geometry in adolescent males. Medicine and Science in Sports and Exercise
Bond B, Williams CA, Barker AR (2017). The reliability of a single protocol to determine endothelial, microvascular and autonomic functions in adolescents.
Clin Physiol Funct Imaging,
37(6), 703-709.
Abstract:
The reliability of a single protocol to determine endothelial, microvascular and autonomic functions in adolescents.
BACKGROUND: Impairments in macrovascular, microvascular and autonomic function are present in asymptomatic youths with clustered cardiovascular disease risk factors. This study determines the within-day reliability and between-day reliability of a single protocol to non-invasively assess these outcomes in adolescents. METHODS: Forty 12- to 15-year-old adolescents (20 boys) visited the laboratory in a fasted state on two occasions, approximately 1 week apart. One hour after a standardized cereal breakfast, macrovascular function was determined via flow-mediated dilation (FMD). Heart rate variability (root mean square of successive R-R intervals; RMSSD) was determined from the ECG-gated ultrasound images acquired during the FMD protocol prior to cuff occlusion. Microvascular function was simultaneously quantified as the peak (PRH) and total (TRH) hyperaemic response to occlusion in the cutaneous circulation of the forearm via laser Doppler imaging. To address within-day reliability, a subset of twenty adolescents (10 boys) repeated these measures 90 min afterwards on one occasion. RESULTS: the within-day typical error and between-day typical error expressed as a coefficient of variation of these outcomes are as follows: ratio-scaled FMD, 5·1% and 10·6%; allometrically scaled FMD, 4·4% and 9·4%; PRH, 11% and 13·3%; TRH, 29·9% and 23·1%; and RMSSD, 17·6% and 17·6%. The within- and between-day test-retest correlation coefficients for these outcomes were all significant (r > 0·54 for all). CONCLUSION: Macrovascular, microvascular and autonomic functions can be simultaneously and non-invasively determined in adolescents using a single protocol with an appropriate degree of reproducibility. Determining these outcomes may provide greater understanding of the progression of cardiovascular disease and aid early intervention.
Abstract.
Author URL.
2016
Vlachopoulos D, Gracia-Marco L, Barker AR, Huybrechts I, Moreno LA, Mouratidou T (2016). Bone health: the independent and combined effects of calcium, Vitamin D and exercise in children and adolescents. In (Ed)
Food and Nutritional Components in Focus, 530-546.
Abstract:
Bone health: the independent and combined effects of calcium, Vitamin D and exercise in children and adolescents
Abstract.
Fessi MS, Zarrouk N, Di Salvo V, Filetti C, Barker AR, Moalla W (2016). Effects of tapering on physical match activities in professional soccer players.
J Sports Sci,
34(24), 2189-2194.
Abstract:
Effects of tapering on physical match activities in professional soccer players.
This study aimed to examine: (i) the effect of decreasing training load (TL) during taper weeks on physical match activities in professional soccer players, and (ii) to disclose the relationship between weekly TL and physical match activities. Rating of perceived exertion was collected after each training session and match to quantify the TL in 19 professional players over 17 standard and 7 taper weeks during the season. Physical match activities were quantified by a computerised match analysis system and compared between standard training and taper weeks. Compared to standard weeks, the duration and frequency of training sessions during the taper weeks decreased (-21.7% and -18.8%, respectively; P
Abstract.
Author URL.
Tomlinson OW, Barker AR, Oades PJ, Williams CA (2016). Exercise capacity following a percutaneous endoscopic gastrostomy in a young female with cystic fibrosis: a case report.
Physiological Reports,
4(16).
Abstract:
Exercise capacity following a percutaneous endoscopic gastrostomy in a young female with cystic fibrosis: a case report
Cystic fibrosis (CF) is a genetic condition affecting the respiratory and gastrointestinal systems, with patients experiencing problems maintaining weight, especially during rapid growth periods such as puberty. The aim of this case report was to monitor the effect of gastrostomy insertion and implementation of overnight supplemental feeding upon clinical outcomes, including body mass index (BMI), lung function (FEV1), and exercise-related variables (maximal oxygen uptake [VO2max] and ventilatory efficiency [VE/VO2]) in an 11-year-old female with CF. Combined incremental and supramaximal exercise testing to exhaustion was performed at four time points: 3 months prior to the procedure (T1), 2 days prior to (T2), 4 months (T3), and 1 year following the procedure (T4). Improvements following gastrostomy insertion were observed at the 1 year follow-up with regards to BMI (+20%); whereas absolute VO2max remained stable and lung function fluctuated throughout the period of observation. Declines in function with regards to body weight relative VO2max (−16.3%) and oxygen uptake efficiency (+7.5%) were observed during this period. This case report is the first to consider exercise-related clinical outcomes in assessing the effect of implementing gastrostomy feeding in CF. The varied direction and magnitude of the associations between variables shows that further investigations are required.
Abstract.
Saynor ZL, Barker AR, Oades PJ, Williams CA (2016). Impaired Pulmonary V˙O2 Kinetics in Cystic Fibrosis Depend on Exercise Intensity.
Med Sci Sports Exerc,
48(11), 2090-2099.
Abstract:
Impaired Pulmonary V˙O2 Kinetics in Cystic Fibrosis Depend on Exercise Intensity.
PURPOSE: This study aimed to investigate the effects of mild-to-moderate cystic fibrosis (CF) on the pulmonary oxygen uptake (V˙O2) kinetics of seven pediatric patients (13.5 ± 2.8 yr) versus seven healthy matched controls (CON; 13.6 ± 2.4 yr). We hypothesized that CF would slow the V˙O2 kinetic response at the onset of moderate (MOD) and very heavy (VH) intensity cycling. METHODS: Changes in breath-by-breath V˙O2, near-infrared spectroscopy-derived muscle deoxygenation ([HHb]) at the vastus lateralis muscle and thoracic bioelectrical impedance-derived heart rate (HR), stroke volume index, and cardiac index were measured during repeat transitions to MOD (90% of the gas exchange threshold) and VH (Δ60%) intensity cycling exercise. RESULTS: During MOD, the phase II V˙O2 τ (P = 0.84, effect size [ES] = 0.11) and the overall mean response time (MRT) (P = 0.52, ES = 0.11) were not significantly slower in CF versus CON. However, during VH exercise, the phase II V˙O2 τ (P = 0.02, ES = 1.28) and MRT (P = 0.01, ES = 1.40) were significantly slower in CF. Cardiac function, central O2 delivery (stroke volume index and cardiac index), and muscle [HHb] kinetics were unaltered in CF. However, the arteriovenous O2 content difference ((Equation is included in full-text article.)) was reduced during VH at 30 s (P = 0.03, ES = 0.37), with a trend for reduced levels at 0 s (P = 0.07, ES = 0.25), 60 s (P = 0.05, ES = 0.28), and 120 s (P = 0.07, ES = 0.25) in CF. Furthermore, (Equation is included in full-text article.)significantly correlated with the VH phase II V˙O2 τ (r = -0.85, P = 0.02) and MRT (r = -0.79, P = 0.03) in CF only. CONCLUSION: Impairments in muscle oxidative metabolism during constant work rate exercise are intensity dependent in young people with mild-to-moderate CF. Specifically, V˙O2 kinetics are slowed during VH but not MOD cycling and appear to be mechanistically linked to impaired muscle O2 extraction and utilization.
Abstract.
Author URL.
Saynor ZL, Barker AR, Oades PJ, Tomlinson OW, Williams CA (2016). Validity and Reliability Concerns Associated with Cardiopulmonary Exercise Testing Young People with Cystic Fibrosis. Respiration, 92(1), 61-62.
2015
Bond B, Williams CA, Jackman SR, Woodward A, Armstrong N, Barker AR (2015). Accumulating exercise and postprandial health in adolescents.
Metabolism: clinical and experimentalAbstract:
Accumulating exercise and postprandial health in adolescents
Purpose: to examine the influence of exercise intensity on postprandial health outcomes in adolescents when exercise is accumulated throughout the day. Methods: 19 adolescents (9 male, 13.7 ± 0.4 y) completed three 1-day trials in a randomised order: 1) rest (CON); or four bouts of 2) 2 x 1 min cycling at 90% peak power with 75 s recovery (high-intensity interval exercise; HIIE); or 3) cycling at 90% of the gas exchange threshold (moderate-intensity exercise; MIE), which was work-matched to HIIE. Each bout was separated by 2 hours. Participants consumed a high fat milkshake for breakfast and lunch. Postprandial triacylglycerol (TAG), glucose, systolic blood pressure (SBP) and fat oxidation were assessed throughout the day. Results: There was no effect of trial on total area under the curve (TAUC) for TAG (P=0.87). TAUC-glucose was lower in HIIE compared to CON (P=0.03, ES=0.42) and MIE (P=0.04, ES=0.41), with no difference between MIE and CON (P=0.89, ES=0.04). Postprandial SBP was lower in HIIE compared to CON (P=0.04, ES=0.50) and MIE (P=0.04, ES=0.40), but not different between MIE and CON (P=0.52, ES=0.11). Resting fat oxidation was increased in HIIE compared to CON (P=0.01, ES=0.74) and MIE (P=0.05, ES=0.51), with no difference between MIE and CON (P=0.37, ES=0.24). Conclusion: Neither exercise trial attenuated postprandial lipaemia. However, accumulating brief bouts of HIIE, but not MIE, reduced postprandial plasma glucose and SBP, and increased resting fat oxidation in adolescent boys and girls. The intensity of accumulated exercise may therefore have important implications for health outcomes in youth.
Abstract.
McNarry MA, Farr C, Middlebrooke A, Welford D, Breese B, Armstrong N, Barker AR (2015). Aerobic Function and Muscle Deoxygenation Dynamics during Ramp Exercise in Children.
Med Sci Sports Exerc,
47(9), 1877-1884.
Abstract:
Aerobic Function and Muscle Deoxygenation Dynamics during Ramp Exercise in Children.
PURPOSE: This study aimed to characterize changes in deoxyhemoglobin ([HHb]) response dynamics in boys and girls during ramp incremental exercise to investigate whether the reduced peak oxygen uptake (peak V˙O2) in girls is associated with poorer matching of muscle O2 delivery to muscle O2 utilization, as evidenced by a more rapid increase in [HHb]. METHODS: Fifty-two children (31 boys, 9.9 ± 0.6 yr, 1.38 ± 0.07 m, 31.70 ± 5.78 kg) completed ramp incremental exercise on a cycle ergometer during which pulmonary gas exchange and muscle oxygenation parameters were measured. RESULTS: When muscle [HHb] was expressed against absolute work rate and V˙O2, girls had an earlier change in [HHb], as evidenced by the lower c/d parameter (girls, 54 ± 20 W, vs boys, 67 ± 19 W, P = 0.023; girls, 0.82 ± 0.28 L·min(-1), vs boys, 0.95 ± 0.19 L·min(-1), P = 0.055) and plateau (girls, 85 ± 12 W, vs boys, 99 ± 18 W, P = 0.031; girls, 1.02 ± 0.25 L·min(-1), vs boys, 1.22 ± 0.28 L·min(-1), P = 0.014). However, when expressed against relative work rate or V˙O2, there were no sex differences in ([HHb]) response dynamics (all P > 0.20). Significant correlations were observed between absolute and fat-free mass normalized peak V˙O2 and the HHb c/d and plateau parameters when expressed against absolute work rate or V˙O2. Furthermore, when entered into a multiple regression model, the [HHb] plateau against absolute V˙O2 contributed 12% of the variance in peak V˙O2 after adjusting for fat-free mass, gas exchange threshold, and body fatness (model R2 = 0.81, P < 0.001). CONCLUSIONS: the sex difference in peak V˙O2 in 9- to 10-yr-old children is, in part, related to sex-specific changes in muscle O2 extraction dynamics during incremental exercise.
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Author URL.
Vlachopoulos D, Barker AR, Williams CA, Knapp KM, Metcalf BS, Gracia-Marco L (2015). Effect of a program of short bouts of exercise on bone health in adolescents involved in different sports: the PRO-BONE study protocol.
BMC Public Health,
15Abstract:
Effect of a program of short bouts of exercise on bone health in adolescents involved in different sports: the PRO-BONE study protocol.
BACKGROUND: Osteoporosis is a skeletal disease associated with high morbidity, mortality and increased economic costs. Early prevention during adolescence appears to be one of the most beneficial practices. Exercise is an effective approach for developing bone mass during puberty, but some sports may have a positive or negative impact on bone mass accrual. Plyometric jump training has been suggested as a type of exercise that can augment bone, but its effects on adolescent bone mass have not been rigorously assessed. The aims of the PRO-BONE study are to: 1) longitudinally assess bone health and its metabolism in adolescents engaged in osteogenic (football), non-osteogenic (cycling and swimming) sports and in a control group, and 2) examine the effect of a 9 month plyometric jump training programme on bone related outcomes in the sport groups. METHODS/DESIGN: This study will recruit 105 males aged 12-14 years who have participated in sport specific training for at least 3 hours per week during the last 3 years in the following sports groups: football (n = 30), cycling (n = 30) and swimming (n = 30). An age-matched control group (n = 15) that does not engage in these sports more than 3 hours per week will also be recruited. Participants will be measured on 5 occasions: 1) at baseline; 2) after 12 months of sport specific training where each sport group will be randomly allocated into two sub-groups: intervention group (sport + plyometric jump training) and sport group (sport only); 3) exactly after the 9 months of intervention; 4) 6 months following the intervention; 5) 12 months following the intervention. Body composition (dual energy X-ray absorptiometry, air displacement plethysmography and bioelectrical impedance), bone stiffness index (ultrasounds), physical activity (accelerometers), diet (24 h recall questionnaire), pubertal maturation (Tanner stage), physical fitness (cardiorespiratory and muscular), bone turnover markers and vitamin D will be measured at each visit. DISCUSSION: the PRO-BONE study is designed to investigate the impact of osteogenic and non-osteogenic sports on bone development in adolescent males during puberty, and how a plyometric jump training programme is associated with body composition parameters.
Abstract.
Author URL.
Bond B, Williams CA, Isic C, Jackman SR, Tolfrey K, Barrett LA, Barker AR (2015). Exercise intensity and postprandial health outcomes in adolescents.
Eur J Appl Physiol,
115(5), 927-936.
Abstract:
Exercise intensity and postprandial health outcomes in adolescents.
PURPOSE: the effect of exercise intensity and sex on postprandial risk factors for cardiovascular disease in adolescents is unknown. We examined the effect of a single bout of work-matched high-intensity interval exercise (HIIE) and moderate-intensity exercise (MIE) on postprandial triacylglycerol (TAG) and systolic blood pressure (SBP) in adolescents. METHOD: Twenty adolescents (10 male, 14.3 ± 0.3 years) completed three 1-day trials: (1) rest (CON); (2) 8 × 1 min cycling at 90 % peak power with 75 s recovery (HIIE); (3) cycling at 90 % of the gas exchange threshold (MIE), 1 h before consuming a high-fat milkshake (1.50 g fat and 80 kJ kg(-1)). Postprandial TAG, SBP and fat oxidation were assessed over 4 h RESULTS: Compared to CON, the incremental area under the curve for TAG (IAUC-TAG) was not significantly lowered in HIIE [P = 0.22, effect size (ES) = 0.24] or MIE (P = 0.65, ES = 0.04) for boys. For girls, HIIE and MIE lowered IAUC-TAG by 34 % (P = 0.02, ES = 0.58) and 38 % (P = 0.09, ES = 0.73), respectively, with no difference between HIIE and MIE (P = 0.74, ES = 0.14). Changes in TAG were not related to energy expenditure during exercise or postprandial fat oxidation. Postprandial SBP (total-AUC pooled for both sexes) was lower in HIIE compared to CON (P = 0.01, ES = 0.68) and MIE (P = 0.02, ES = 0.60), with no difference between MIE and CON (P = 0.45, ES = 0.14). CONCLUSION: a single bout of HIIE and MIE, performed 1 h before an HFM, can meaningfully attenuate IAUC-TAG in girls but not boys. Additionally, HIIE, but not MIE, may lower postprandial SBP in normotensive adolescents.
Abstract.
Author URL.
Bond B, Gates PE, Jackman SR, Corless LM, Williams CA, Barker AR (2015). Exercise intensity and the protection from postprandial vascular dysfunction in adolescents.
Am J Physiol Heart Circ Physiol,
308(11), H1443-H1450.
Abstract:
Exercise intensity and the protection from postprandial vascular dysfunction in adolescents.
Acute exercise transiently improves endothelial function and protects the vasculature from the deleterious effects of a high-fat meal (HFM). We sought to identify whether this response is dependent on exercise intensity in adolescents. Twenty adolescents (10 male, 14.3 ± 0.3 yr) completed three 1-day trials: 1) rest (CON); 2) 8 × 1 min cycling at 90% peak power with 75 s recovery [high-intensity interval exercise (HIIE)]; and 3) cycling at 90% of the gas exchange threshold [moderate-intensity exercise (MIE)] 1 h before consuming a HFM (1.50 g/kg fat). Macrovascular and microvascular endothelial function was assessed before and immediately after exercise and 3 h after the HFM by flow-mediated dilation (FMD) and laser Doppler imaging [peak reactive hyperemia (PRH)]. FMD and PRH increased 1 h after HIIE [P < 0.001, effect size (ES) = 1.20 and P = 0.048, ES = 0.56] but were unchanged after MIE. FMD and PRH were attenuated 3 h after the HFM in CON (P < 0.001, ES = 1.78 and P = 0.02, ES = 0.59). FMD remained greater 3 h after the HFM in HIIE compared with MIE (P < 0.001, ES = 1.47) and CON (P < 0.001, ES = 2.54), and in MIE compared with CON (P < 0.001, ES = 1.40). Compared with CON, PRH was greater 3 h after the HFM in HIIE (P = 0.02, ES = 0.71) and MIE (P = 0.02, ES = 0.84), with no differences between HIIE and MIE (P = 0.72, ES = 0.16). Plasma triacylglycerol concentration and total antioxidant status concentration were not different between trials. We conclude that exercise intensity plays an important role in protecting the vasculature from the deleterious effects of a HFM. Performing HIIE may provide superior vascular benefits than MIE in adolescent groups.
Abstract.
Author URL.
Armstrong N, Barker AR, McManus AM (2015). Muscle metabolism changes with age and maturation: How do they relate to youth sport performance?.
Br J Sports Med,
49(13), 860-864.
Abstract:
Muscle metabolism changes with age and maturation: How do they relate to youth sport performance?
AIM: to provide an evidence-based review of muscle metabolism changes with sex-, age- and maturation with reference to the development of youth sport performance. METHODS: a narrative review of data from both invasive and non-invasive studies, from 1970 to 2015, founded on personal databases supported with computer searches of PubMed and Google Scholar. RESULTS: Youth sport performance is underpinned by sex-, age- and maturation-related changes in muscle metabolism. Investigations of muscle size, structure and metabolism; substrate utilisation; pulmonary oxygen uptake kinetics; muscle phosphocreatine kinetics; peak anaerobic and aerobic performance; and fatigue resistance; determined using a range of conventional and emerging techniques present a consistent picture. Age-related changes have been consistently documented but specific and independent maturation-related effects on muscle metabolism during exercise have proved elusive to establish. Children are better equipped for exercise supported primarily by oxidative metabolism than by anaerobic metabolism. Sexual dimorphism is apparent in several physiological variables underpinning youth sport performance. As young people mature there is a progressive but asynchronous transition into an adult metabolic profile. CONCLUSIONS: the application of recent developments in technology to the laboratory study of the exercising child and adolescent has both supplemented existing knowledge and provided novel insights into developmental exercise physiology. A sound foundation of laboratory-based knowledge has been established but the lack of rigorously designed child-specific and sport-specific testing environments has clouded the interpretation of the data in real life situations. The primary challenge remains the translation of laboratory research into the optimisation of youth sports participation and performance.
Abstract.
Author URL.
Armstrong N, Barker AR, McManus AM (2015). Muscle metabolism changes with age and maturation: How do they relate to youth sport performance?.
British Journal of Sports Medicine,
49(13), 860-864.
Abstract:
Muscle metabolism changes with age and maturation: How do they relate to youth sport performance?
Aim: to provide an evidence-based review of muscle metabolism changes with sex-, age- and maturation with reference to the development of youth sport performance. Methods: a narrative review of data from both invasive and non-invasive studies, from 1970 to 2015, founded on personal databases supported with computer searches of PubMed and Google Scholar. Results: Youth sport performance is underpinned by sex-, age- and maturation-related changes in muscle metabolism. Investigations of muscle size, structure and metabolism; substrate utilisation; pulmonary oxygen uptake kinetics; muscle phosphocreatine kinetics; peak anaerobic and aerobic performance; and fatigue resistance; determined using a range of conventional and emerging techniques present a consistent picture. Age-related changes have been consistently documented but specific and independent maturation-related effects on muscle metabolism during exercise have proved elusive to establish. Children are better equipped for exercise supported primarily by oxidative metabolism than by anaerobic metabolism. Sexual dimorphism is apparent in several physiological variables underpinning youth sport performance. As young people mature there is a progressive but asynchronous transition into an adult metabolic profile. Conclusions: the application of recent developments in technology to the laboratory study of the exercising child and adolescent has both supplemented existing knowledge and provided novel insights into developmental exercise physiology. A sound foundation of laboratory-based knowledge has been established but the lack of rigorously designed child-specific and sport-specific testing environments has clouded the interpretation of the data in real life situations. The primary challenge remains the translation of laboratory research into the optimisation of youth sports participation and performance.
Abstract.
Bond B, Cockcroft EJ, Williams CA, Harris S, Gates PE, Jackman SR, Armstrong N, Barker AR (2015). Two weeks of high-intensity interval training improves novel but not traditional cardiovascular disease risk factors in adolescents.
Am J Physiol Heart Circ Physiol,
309(6), H1039-H1047.
Abstract:
Two weeks of high-intensity interval training improves novel but not traditional cardiovascular disease risk factors in adolescents.
High-intensity interval training (HIIT) improves traditional cardiovascular disease (CVD) risk factors in adolescents, but no study has identified the influence of HIIT on endothelial and autonomic function in this group. Thirteen 13- to 14-yr-old adolescents (6 girls) completed six HIIT sessions over 2 wk. Each training session consisted of eight to ten 1-min repetitions of cycling at 90% peak power interspersed with 75 s of unloaded cycling. Traditional (triglycerides, cholesterol, glucose, insulin, and blood pressure) and novel [flow-mediated dilation (FMD), heart rate variability (HRV)] CVD risk factors were assessed in a fasted and postprandial state before (PRE), 1 day after (POST-1D), and 3 days after (POST-3D) training. Aerobic fitness was determined PRE and POST-3D. Two weeks of HIIT had no effect on aerobic fitness or traditional CVD risk factors determined in the fasted or postprandial state (P > 0.15). Compared with PRE, fasted FMD was improved POST-1D [P = 0.003, effect size (ES) = 0.70] but not POST-3D (P = 0.32, ES = 0.22). Fasted FMD was greater POST-1D compared with POST-3D (P = 0.04, ES = 0.48). Compared with PRE, postprandial FMD was greater POST-1D (P < 0.001, ES = 1.01) and POST-3D (P = 0.01, ES = 0.60). Fasted HRV was greater POST-1D (P = 0.001, ES = 0.71) and POST-3D (P = 0.02, ES = 0.44). The test meal lowered HRV in all laboratory visits (P < 0.001, ES = 0.59), but there were no differences in postprandial HRV between visits (P > 0.32 for all). Two weeks of HIIT enhanced endothelial function and HRV without improvements in traditional CVD risk factors. However, most of this favorable adaptation was lost POST-3D, suggesting that regularly performing high-intensity exercise is needed to maintain these benefits.
Abstract.
Author URL.
2014
Williams CA, Saynor ZL, Tomlinson OW, Barker AR (2014). Cystic fibrosis and physiological responses to exercise.
Expert Rev Respir Med,
8(6), 751-762.
Abstract:
Cystic fibrosis and physiological responses to exercise.
Cardiopulmonary exercise testing is underutilized within the clinical management of patients with cystic fibrosis. But within the last 5 years, there has been considerable interest in its implementation, which has included deliberations by the European Cystic Fibrosis Society about incorporating this method within the clinical assessment of patients. This review examines the current use of cardiopulmonary exercise testing in assessing the extent and cause(s) of exercise limitation from a pediatric perspective. Examples of the measured parameters and their interpretation are provided. Critical synthesis of recent work in the oxygen uptake (VO2) kinetics response to and following exercise is also discussed, and although identified more as a research tool, its utilization advances researchers understanding of the cardiovascular, respiratory and muscular limitations to exercise tolerance. Finally, exercise and its application in therapeutic interventions are highlighted and a number of recommendations made about the utility of exercise prescription.
Abstract.
Author URL.
Cockcroft EJ, Williams CA, Tomlinson OW, Vlachopoulos D, Jackman SR, Armstrong N, Barker AR (2014). High intensity interval exercise is an effective alternative to moderate intensity exercise for improving glucose tolerance and insulin sensitivity in adolescent boys.
Journal of Science and Medicine in SportAbstract:
High intensity interval exercise is an effective alternative to moderate intensity exercise for improving glucose tolerance and insulin sensitivity in adolescent boys
Objectives: High-intensity interval exercise (HIIE) may offer a time efficient means to improve health outcomes compared to moderate-intensity exercise (MIE). This study examined the acute effect of HIIE compared to a work-matched bout of MIE on glucose tolerance, insulin sensitivity (IS), resting fat oxidation and exercise enjoyment in adolescent boys. Design: Within-measures design with counterbalanced experimental conditions. Methods: Nine boys (14.2. ±. 0.4 years) completed three conditions on separate days in a counterbalanced order: (1) HIIE; (2) work matched MIE, both on a cycle ergometer; and (3) rest (CON). An oral glucose tolerance test (OGTT) was performed after exercise or rest and the area under curve (AUC) responses for plasma [glucose] and [insulin] were calculated, and IS estimated (Cederholm index). Energy expenditure and fat oxidation were measured following the OGTT using indirect calorimetry. Exercise enjoyment was assessed using the Physical Activity Enjoyment Scale. Results: the incremental AUC (iAUC) for plasma [glucose] was reduced following both MIE (-23.9%, P = 0.013, effect size [ES]. = -0.64) and HIIE (-28.9%, P = 0.008, ES. = -0.84) compared to CON. The iAUC for plasma [insulin] was lower for HIIE (-24.2%, P = 0.021, ES. = -0.71) and MIE (-29.1%, P = 0.012, ES. = -0.79) compared to CON. IS increased by 11.2% after HIIE (P = 0.03, ES. = 0.76) and 8.4% after MIE (P = 0.10, ES. = 0.58). There was a trend for an increase in fat oxidation following HIIE (P = 0.097, ES. = 0.70). Both HIIE and MIE were rated as equally enjoyable (P >. 0.05, ES.
Abstract.
Saynor ZL, Barker AR, Oades PJ, Williams CA (2014). Impaired aerobic function in patients with cystic fibrosis during ramp exercise.
Med Sci Sports Exerc,
46(12), 2271-2278.
Abstract:
Impaired aerobic function in patients with cystic fibrosis during ramp exercise.
PURPOSE: This study aimed to document the matching of muscle O2 delivery to O2 use in young patients with cystic fibrosis (CF) from muscle deoxygenation (HHb) dynamics during ramp exercise. METHODS: Ten patients with stable, mild-to-moderate CF (12.7 ± 2.8 yr) and 10 healthy controls (CON, 12.8 ± 2.8 yr) completed a combined ramp and supramaximal cycling test to determine maximal O2 uptake (V˙O2max). Changes in gas exchange and ventilation, HR, and m. vastus lateralis HHb (near-infrared spectroscopy) were assessed. Δ[HHb]-work rate and Δ[HHb]-V˙O2 profiles were normalized and fit using a sigmoid function. RESULTS: Aerobic function was impaired in CF, indicated by very likely reduced fat-free mass-normalized V˙O2max (mean difference, ±90% confidence interval: -7.9 mL·kg·min, ±6.1), very likely lower V˙O2 gain (-1.44 mL·min·W, ±1.12), and a likely slower V˙O2 mean response time (11 s, ±13). An unclear effect was found upon the absolute and relative work rate (-14 W, ±44, and -0.7% peak power output, ±12.0, respectively) and the absolute and percentage (-0.10 L·min, ±0.43, and 3.3% V˙O2max, ±6.0) V˙O2 corresponding to 50% Δ[HHb] amplitude, respectively, between groups. However, arterial oxygen saturation (SpO2) was very likely lower in CF (-1%, ±1) and demonstrated moderate-to-very large relations with parameters of aerobic function. CONCLUSIONS: Young patients with mild-to-moderate CF present with impaired aerobic function during ramp incremental cycling exercise. Because the rate of fractional O2 extraction during ramp cycling exercise was not altered by CF, yet SpO2 was lower, the present findings support the notion of centrally mediated oxygen delivery to principally limit the aerobic function of pediatric patients with CF during ramp incremental cycling exercise.
Abstract.
Author URL.
Breese BC, Barker AR, Armstrong N, Fulford J, Williams CA (2014). Influence of thigh activation on the VO₂ slow component in boys and men.
Eur J Appl Physiol,
114(11), 2309-2319.
Abstract:
Influence of thigh activation on the VO₂ slow component in boys and men.
PURPOSE: During constant work rate exercise above the lactate threshold (LT), the initial rapid phase of pulmonary oxygen uptake (VO₂) kinetics is supplemented by an additional VO₂ slow component (VO₂Sc) which reduces the efficiency of muscular work. The VO₂Sc amplitude has been shown to increase with maturation but the mechanisms are poorly understood. We utilized the transverse relaxation time (T₂) of muscle protons from magnetic resonance imaging (MRI) to test the hypothesis that a lower VO₂ slow component (VO₂Sc) amplitude in children would be associated with a reduced muscle recruitment compared to adults. METHODS: Eight boys (mean age 11.4 ± 0.4) and eight men (mean age 25.3 ± 3.3 years) completed repeated step transitions of unloaded-to-very heavy-intensity (U → VH) exercise on a cycle ergometer. MRI scans of the thigh region were acquired at rest and after VH exercise up to the VO₂Sc time delay (ScTD) and after 6 min. T₂ for each of eight muscles was adjusted in relation to cross-sectional area and then summed to provide the area-weighted ΣT₂ as an index of thigh recruitment. RESULTS: There were no child/adult differences in the relative VO₂Sc amplitude [Boys 14 ± 7 vs. Men 18 ± 3 %, P = 0.15, effect size (ES) = 0.8] during which the change (∆) in area-weighted ΣT₂ between the ScTD and 6 min was not different between groups (Boys 1.6 ± 1.2 vs. Men 2.3 ± 1.1 ms, P = 0.27, ES = 0.6). A positive and strong correlation was found between the relative VO₂Sc amplitude and the magnitude of the area-weighted ∆ΣT₂ in men (r = 0.92, P = 0.001) but not in boys (r = 0.09, P = 0.84). CONCLUSIONS: This study provides evidence to show that progressive muscle recruitment (as inferred from T₂ changes) contributes to the development of the VO₂Sc during intense submaximal exercise independent of age.
Abstract.
Author URL.
Breese BC, Barker AR, Armstrong N, Fulford J, Williams CA (2014). Influence of thigh activation on the [Formula Presented] O<inf>2</inf> slow component in boys and men.
European Journal of Applied Physiology,
114(11), 2309-2319.
Abstract:
Influence of thigh activation on the [Formula Presented] O2 slow component in boys and men
Purpose: During constant work rate exercise above the lactate threshold (LT), the initial rapid phase of pulmonary oxygen uptake ([Formula Presented]O2) kinetics is supplemented by an additional [Formula Presented]O2 slow component ([Formula Presented]O2Sc) which reduces the efficiency of muscular work. The [Formula Presented]O2Sc amplitude has been shown to increase with maturation but the mechanisms are poorly understood. We utilized the transverse relaxation time (T2) of muscle protons from magnetic resonance imaging (MRI) to test the hypothesis that a lower [Formula Presented]O2 slow component ([Formula Presented]O2Sc) amplitude in children would be associated with a reduced muscle recruitment compared to adults.
Abstract.
Breese BC, Barker AR, Armstrong N, Fulford J, Williams CA (2014). Influence of thigh muscle activation on pulmonary O2 uptake kinetics during very heavy intensity exercise in boys and men.
European Journal of Applied Physiology,
114, 2309-2319.
Abstract:
Influence of thigh muscle activation on pulmonary O2 uptake kinetics during very heavy intensity exercise in boys and men
During constant work rate exercise above the
lactate threshold (LT ), the initial rapid phase of pulmonary
oxygen uptake (˙V O2) kinetics is supplemented by an
additional ˙V O2 slow component (˙V O2Sc) which reduces
the efficiency of muscular work. The ˙V O2Sc amplitude has
been shown to increase with maturation but the mechanisms
are poorly understood. We utilized the transverse
relaxation time (T2) of muscle protons from magnetic resonance
imaging (MRI) to test the hypothesis that a lower
˙V
O2 slow component (˙V O2Sc) amplitude in children would
be associated with a reduced muscle recruitment compared
to adults.
Methods Eight boys (mean age 11.4 ± 0.4) and eight
men (mean age 25.3 ± 3.3 years) completed repeated step
transitions of unloaded-to-very heavy-intensity (U → VH)
exercise on a cycle ergometer. MRI scans of the thigh
region were acquired at rest and after VH exercise up to
the ˙V O2Sc time delay (ScTD) and after 6 min. T2 for each of eight muscles was adjusted in relation to cross-sectional
area and then summed to provide the area-weighted ΣT2 as
an index of thigh recruitment.
Results T here were no child/adult differences in the relative
˙VO2Sc amplitude [Boys 14 ± 7 vs. Men 18 ± 3 %,
P = 0.15, effect size (ES) = 0.8] during which the change
(Δ) in area-weighted ΣT2 between the ScTD and 6 min
was not different between groups (Boys 1.6 ± 1.2 vs. Men
2.3 ± 1.1 ms, P = 0.27, ES = 0.6). A positive and strong
correlation was found between the relative ˙V O2Sc amplitude
and the magnitude of the area-weighted ΔΣT2 in men
(r = 0.92, P = 0.001) but not in boys (r = 0.09, P = 0.84).
Conclusions T his study provides evidence to show
that progressive muscle recruitment (as inferred from T2
changes) contributes to the development of the ˙V O2Sc during
intense submaximal exercise independent of age.
Abstract.
Willcocks RJ, Fulford J, Armstrong N, Barker AR, Williams CA (2014). Muscle metabolism during fatiguing isometric quadriceps exercise in adolescents and adults.
Appl Physiol Nutr Metab,
39(4), 439-445.
Abstract:
Muscle metabolism during fatiguing isometric quadriceps exercise in adolescents and adults.
Children and adolescents are less susceptible to muscle fatigue during repeated bouts of high-intensity exercise than adults, but the physiological basis for these differences is not clear. The purpose of the current investigation was to investigate the muscle metabolic responses, using 31-phosphorus magnetic resonance spectroscopy, during fatiguing isometric quadriceps exercise in 13 adolescents (7 females) and 14 adults (8 females). Participants completed 30 maximal voluntary contractions (6-s duration) separated by 6 s of rest. Fatigue was quantified as the relative decrease in force over the test. Fatigue was not significantly different with age (p = 0.20) or sex (p = 0.63). Metabolic perturbation (change in phosphocreatine, inorganic phosphate, and ADP concentrations) was significantly greater in adults compared with adolescents; no sex effects were present. Muscle pH did not differ with age or sex. Phosphocreatine recovery following exercise was not significantly different with age (p = 0.27) or sex (p = 0.97) but a significant interaction effect was present (p = 0.04). Recovery tended to be faster in boys than men but slower in girls than women, though no significant group differences were identified. The results of this study show that at a comparable level of muscle fatigue, the metabolic profile is profoundly different between adolescents and adults.
Abstract.
Author URL.
Saynor ZL, Barker AR, Oades PJ, Williams CA (2014). The effect of ivacaftor in adolescents with cystic fibrosis (G551D mutation): an exercise physiology perspective.
Pediatr Phys Ther,
26(4), 454-461.
Abstract:
The effect of ivacaftor in adolescents with cystic fibrosis (G551D mutation): an exercise physiology perspective.
PURPOSE: the purpose of this report was to evaluate the influence of 12 weeks of ivacaftor treatment on the aerobic function of 2 teenage patients with cystic fibrosis (CF; ΔF508/G551D) using a maximal cardiopulmonary exercise test. SUMMARY OF KEY POINTS: One patient, with relatively mild disease, demonstrated no clinically meaningful changes in maximal oxygen uptake ((Equation is included in full-text article.)O2max). However, in the second case, with more established lung disease on imaging, (Equation is included in full-text article.)O2max improved by approximately 30%, an improvement out of proportion with early lung function changes. This improvement resulted from increased muscle oxygen delivery and extraction. STATEMENT OF CONCLUSIONS: Cardiopulmonary exercise testing can monitor the extent and cause(s) of change following interventions such as ivacaftor, with the potential to identify functional changes independent from spirometry indices. RECOMMENDATIONS FOR CLINICAL PRACTICE: Cardiopulmonary exercise testing represents an important and comprehensive clinical assessment tool, and its use as an outcome measure in the functional assessment of patients with CF is encouraged.
Abstract.
Author URL.
Barker AR, Trebilcock E, Breese B, Jones AM, Armstrong N (2014). The effect of priming exercise on O2 uptake kinetics, muscle O2 delivery and utilization, muscle activity, and exercise tolerance in boys.
Appl Physiol Nutr Metab,
39(3), 308-317.
Abstract:
The effect of priming exercise on O2 uptake kinetics, muscle O2 delivery and utilization, muscle activity, and exercise tolerance in boys.
This study used priming exercise in young boys to investigate (i) how muscle oxygen delivery and oxygen utilization, and muscle activity modulate oxygen uptake kinetics during exercise; and (ii) whether the accelerated oxygen uptake kinetics following priming exercise can improve exercise tolerance. Seven boys that were aged 11.3 ± 1.6 years completed either a single bout (bout 1) or repeated bouts with 6 min of recovery (bout 2) of very heavy-intensity cycling exercise. During the tests oxygen uptake, muscle oxygenation, muscle electrical activity and exercise tolerance were measured. Priming exercise most likely shortened the oxygen uptake mean response time (change, ±90% confidence limits; -8.0 s, ±3.0), possibly increased the phase II oxygen uptake amplitude (0.11 L·min(-1), ±0.09) and very likely reduced the oxygen uptake slow component amplitude (-0.08 L·min(-1), ±0.07). Priming resulted in a likely reduction in integrated electromyography (-24% baseline, ±21% and -25% baseline, ±19) and a very likely reduction in Δ deoxyhaemoglobin/Δoxygen uptake (-0.16, ±0.11 and -0.09, ±0.05) over the phase II and slow component portions of the oxygen uptake response, respectively. A correlation was present between the change in tissue oxygenation index during bout 2 and the change in the phase II (r = -0.72, likely negative) and slow component (r = 0.72, likely positive) oxygen uptake amplitudes following priming exercise, but not for muscle activity. Exercise tolerance was likely reduced (change -177 s, ±180) following priming exercise. The altered phase II and slow component oxygen uptake amplitudes in boys following priming exercise are linked to an improved localised matching of muscle oxygen delivery to oxygen uptake and not muscle electrical activity. Despite more rapid oxygen uptake kinetics following priming exercise, exercise tolerance was not enhanced.
Abstract.
Author URL.
Barker AR, Day J, Smith A, Bond B, Williams CA (2014). The influence of 2 weeks of low-volume high-intensity interval training on health outcomes in adolescent boys.
J Sports Sci,
32(8), 757-765.
Abstract:
The influence of 2 weeks of low-volume high-intensity interval training on health outcomes in adolescent boys.
The present study aimed to establish whether 2 weeks of high-intensity interval training would have a beneficial effect on aerobic fitness, fat oxidation, blood pressure and body mass index (BMI) in healthy adolescent boys. Ten adolescent boys (15.1 ± 0.3 years, 1.3 ± 0.2 years post-estimated peak height velocity) completed six sessions of Wingate-style high-intensity interval training over a 2-week period. The first session consisted of four sprints with training progressed to seven sprints in the final session. High-intensity interval training had a beneficial effect on maximal O2 uptake (mean change, ±90% confidence intervals: 0.19 L · min(-1), ±0.19, respectively), on the O2 uptake at the gas exchange threshold (0.09 L · min(-1), ±0.13) and on the O2 cost of sub-maximal exercise (-0.04 L · min(-1), ±0.04). A beneficial effect on the contribution of lipid (0.06 g · min(-1), ±0.06) and carbohydrate (-0.23 g · min(-1), ±0.14) oxidation was observed during sub-maximal exercise, but not for the maximal rate of fat oxidation (0.04 g · min(-1), ±0.08). Systolic blood pressure (1 mmHg, ±4) and BMI (0.1 kg · m2, ±0.1) were not altered following training. These data demonstrate that meaningful changes in health outcomes are possible in healthy adolescent boys after just six sessions of high-intensity interval training over a 2-week period.
Abstract.
Author URL.
Fulford J, Liepa A, Barker AR, Meakin JR (2014). The reliability of 31P-MRS and NIRS measurements of spinal muscle function.
International Journal of Sports Medicine,
35(13), 1078-1083.
Abstract:
The reliability of 31P-MRS and NIRS measurements of spinal muscle function.
Phosphorous magnetic resonance spectroscopy (31P-MRS) and near-infra red spectroscopy (NIRS) provide methods for measuring spinal muscle function non-invasively but their reliability is not established. The aim of this study was assess the reliability (ICC) and error magnitude (CV%) of measurements of muscle phosphocreatine (PCr), tissue oxygenation index (TOI), and muscle deoxyhaemoglobin (HHb) acquired during fatigue and in recovery after 24 s exercise in the lumbar muscles. Ten healthy participants (19-25 years, 5 male, 5 female) performed exercise that involved holding the upper body unsupported in slight extension until fatigue and then, after 30 minutes of rest, for repeated bursts of 24 seconds. ICCs indicated good to excellent reliability of baseline measures (TOI:0.75) and of amplitude changes during fatigue (PCr:0.73, TOI:0.69, HHb:0.80), and recovery (HHb:0.96) and poor to fair reliability for time constants describing rates of change during fatigue (PCr:0.11) and recovery (PCr:0.31, HHb:0.47). CV% indicated varying relative measurement error across baseline measures (TOI:5%), amplitude changes during fatigue (PCr:7%, TOI:38%, HHb:31%) and recovery (HHb:31%), and in time constants for fatigue (PCr:39%) and recovery (PCr:20%, HHb:37%). The results suggested that reliability would be sufficient for future studies on spinal muscle function but that measurement error may be too large to evaluate individuals.
Abstract.
Willcocks RJ, Fulford J, Barker AR, Armstrong N, Williams CA (2014). Two protocols to measure mitochondrial capacity in women and adolescent girls: a 31P-MRS preliminary study.
Pediatr Exerc Sci,
26(2), 210-217.
Abstract:
Two protocols to measure mitochondrial capacity in women and adolescent girls: a 31P-MRS preliminary study.
The phosphocreatine (PCr) recovery time constant (τ) following exercise provides a measure of mitochondrial oxidative capacity. The purpose of this investigation was to use 2 different protocols to determine τ in adolescent females. 31P-MR spectra were collected during 2 exercise tests in 6 adolescent girls (13.8 ± 0.3 y) and 7 women (23.2 ± 3.4 y). The first test consisted of 23 repeated 4 seconds maximal isometric calf contractions separated by 12-second recovery; PCr recovery between the final 18 contractions was used to calculate τ. The second test was a sustained 20-second maximal contraction; recovery was fitted with an exponential function to measure τ. PCr τ did not significantly differ between groups: (gated exercise: 4 girls: 16 ± 5 s, 7 women: 17 ± 5 s, p; sustained exercise: 6 girls: 19 ± 6 s, 7 women: 19 ± 4 s). Bland-Altman analysis demonstrated a close agreement between sustained and gated exercise. Both gated and sustained exercise appear feasible in a pediatric population, and offer a noninvasive evaluation of mitochondrial oxidative capacity.
Abstract.
Author URL.
2013
Saynor ZL, Barker AR, Oades PJ, Williams CA (2013). A protocol to determine valid V˙O2max in young cystic fibrosis patients.
J Sci Med Sport,
16(6), 539-544.
Abstract:
A protocol to determine valid V˙O2max in young cystic fibrosis patients.
OBJECTIVES: Measuring aerobic fitness (V˙O2max) via a maximal cardiopulmonary exercise test is an important clinical tool in cystic fibrosis. This study sought to establish: (1) the validity of traditional criteria to verify maximal efforts during a ramp cardiopulmonary exercise test; and (2) whether V˙O2 measured during an exhaustive cardiopulmonary exercise test represents a valid V˙O2max in paediatric patients, using a subsequent exhaustive supramaximal (Smax) exercise test. DESIGN: Cross-sectional. METHODS: Fourteen patients (7-18 years; 10 males) completed an exhaustive ramp test to determine V˙O2max. Following 15-min recovery, Smax (110% ramp peak power output) was performed. RESULTS: Ramp test V˙O2peak was significantly higher than V˙O2 documented at traditional endpoint criteria, including a RER of 1.00 (0.99±0.47 L min(-1) vs. 1.83±0.78 L min(-1), p
Abstract.
Author URL.
Saynor ZL, Barker AR, Oades PJ, Williams CA (2013). A protocol to determine valid V̇O2max in young cystic fibrosis patients.
Journal of Science and Medicine in Sport,
16(6), 539-544.
Abstract:
A protocol to determine valid V̇O2max in young cystic fibrosis patients
Objectives: Measuring aerobic fitness (V̇O2max) via a maximal cardiopulmonary exercise test is an important clinical tool in cystic fibrosis. This study sought to establish: (1) the validity of traditional criteria to verify maximal efforts during a ramp cardiopulmonary exercise test; and (2) whether V̇O2 measured during an exhaustive cardiopulmonary exercise test represents a valid V̇O2max in paediatric patients, using a subsequent exhaustive supramaximal (Smax) exercise test. Design: Cross-sectional. Methods: Fourteen patients (7-18 years; 10 males) completed an exhaustive ramp test to determine V̇O2max. Following 15-min recovery, Smax (110% ramp peak power output) was performed. Results: Ramp test V̇O2peak was significantly higher than V̇O2 documented at traditional endpoint criteria, including a RER of 1.00 (0.99±0.47Lmin-1 vs. 1.83±0.78Lmin-1, p
Abstract.
Nimmerichter A, Holdhaus J, Mehnen L, Vidotto C, Loidl M, Barker AR (2013). Effects of negative air ions on oxygen uptake kinetics, recovery and performance in exercise: a randomized, double-blinded study.
International Journal of Biometeorology, 1-10.
Abstract:
Effects of negative air ions on oxygen uptake kinetics, recovery and performance in exercise: a randomized, double-blinded study
Limited research has suggested that acute exposure to negatively charged ions may enhance cardio-respiratory function, aerobic metabolism and recovery following exercise. To test the physiological effects of negatively charged air ions, 14 trained males (age: 32 ± 7 years; {Mathematical expression}: 57 ± 7 mL min -1 kg -1 ) were exposed for 20 min to either a high-concentration of air ions (ION: 220 ± 30 × 10 3. ions cm -3 ) or normal room conditions (PLA: 0.1 ± 0.06 × 10 3. ions cm -3 ) in an ionization chamber in a double-blinded, randomized order, prior to performing: (1) a bout of severe-intensity cycling exercise for determining the time constant of the phase II {Mathematical expression} response (τ) and the magnitude of the {Mathematical expression} slow component (SC); and (2) a 30-s Wingate test that was preceded by three 30-s Wingate tests to measure plasma [adrenaline] (ADR), [nor-adrenaline]. (N-ADR) and blood [lactate] (B Lac ) over 20 min during recovery in the ionization chamber. There was no difference between ION and PLA for the phase II {Mathematical expression}τ (32 ± 14 s vs. 32 ± 14 s; P = 0.7) or {Mathematical expression} SC (404 ± 214 mL vs 482 ± 217 mL; P = 0.17). No differences between ION and PLA were observed at any time-point for ADR, N-ADR and B Lac. as well as on peak and mean power output during the Wingate tests (all P. >. 0.05). A high-concentration of negatively charged air ions had no effect on aerobic metabolism during severe-intensity exercise or on performance or the recovery of the adrenergic and metabolic responses after repeated-sprint exercise in trained athletes. © 2013 ISB.
Abstract.
Saynor ZL, Barker AR, Oades PJ, Williams CA (2013). Reproducibility of maximal cardiopulmonary exercise testing for young cystic fibrosis patients.
Journal of Cystic Fibrosis,
12(6), 644-650.
Abstract:
Reproducibility of maximal cardiopulmonary exercise testing for young cystic fibrosis patients
Background: the reproducibility of cardiopulmonary exercise testing (CPET) has not been established in young cystic fibrosis (CF) patients using a valid protocol. Methods: Thirteen 7-18. year olds completed three CPETs, separated by 48. h and 4-6. weeks. CPET involved a ramp-incremental cycling test with supramaximal verification. Results: Maximal oxygen uptake was repeatedly determined with no learning effect and typical errors expressed as a coefficient of variation (TECV%) of 9.3% (48h) and 13.3% (4-6weeks). The reproducibility of additional parameters of aerobic function [gas exchange threshold (TECV%: 11.2%, 16.8%); VO2 mean response time (TECV%: 37.8%, 89.4%); VO2 gain (TECV%: 17.4%, 24.5%)] and clinical utility [e.g. SaO2% (TECV%: 2.2%, 3.1%); ventilatory drive (VE/VCO2-slope) (TECV%: 7.8%, 17.7%)] was also established over the short- and the medium-term, respectively. Conclusion: These results establish limits of variability to determine meaningful changes over the short- and the medium-term for CPET outcomes in young CF patients. © 2013 European Cystic Fibrosis Society.
Abstract.
Saynor ZL, Barker AR, Oades PJ, Williams CA (2013). Reproducibility of maximal cardiopulmonary exercise testing for young cystic fibrosis patients.
J Cyst Fibros,
12(6), 644-650.
Abstract:
Reproducibility of maximal cardiopulmonary exercise testing for young cystic fibrosis patients.
BACKGROUND: the reproducibility of cardiopulmonary exercise testing (CPET) has not been established in young cystic fibrosis (CF) patients using a valid protocol. METHODS: Thirteen 7-18 year olds completed three CPETs, separated by 48 h and 4-6 weeks. CPET involved a ramp-incremental cycling test with supramaximal verification. RESULTS: Maximal oxygen uptake was repeatedly determined with no learning effect and typical errors expressed as a coefficient of variation (TE(CV%)) of 9.3% (48 h) and 13.3% (4-6 weeks). The reproducibility of additional parameters of aerobic function [gas exchange threshold (TE(CV%): 11.2%, 16.8%); VO2 mean response time (TE(CV%): 37.8%, 89.4%); VO2 gain (TE(CV%): 17.4%, 24.5%)] and clinical utility [e.g. SaO2% (TE(CV%): 2.2%, 3.1%); ventilatory drive (V(E)/VCO2-slope) (TE(CV%): 7.8%, 17.7%)] was also established over the short- and the medium-term, respectively. CONCLUSION: These results establish limits of variability to determine meaningful changes over the short- and the medium-term for CPET outcomes in young CF patients.
Abstract.
Author URL.
2012
Saynor ZL, Barker AR, Oades PJ, Williams CA (2012). 168 a protocol to determine O2max in young patients with cystic fibrosis: recommendations for clinical practice. Journal of Cystic Fibrosis, 11
Barker AR, Armstrong N (2012). Aerobic Power, Tests of. In (Ed) Encyclopedia of Exercise Medicine in Health and Disease, 32-37.
Barker AR, Bond B, Toman C, Williams CA, Armstrong N (2012). Critical power in adolescents: physiological bases and assessment using all-out exercise.
Eur J Appl Physiol,
112(4), 1359-1370.
Abstract:
Critical power in adolescents: physiological bases and assessment using all-out exercise.
This study examined whether critical power (CP) in adolescents: (1) provides a landmark for maximal steady-state exercise; and (2) can be determined using 'all-out' exercise. Nine active 14-15 year olds (6 females, 3 males) performed five cycling tests: (1) a ramp test to determine VO(2peak); (2) up to four constant power output tests to determine CP; (3-4) constant power output exercise 10% above and 10% below CP; and (5) a 3 min all-out cycle test to establish the end power (EP) at 90 and 180 s of exercise. All participants completed 30 min of exercise below CP and were characterized by steady-state blood lactate and VO(2) profiles. In contrast, time to exhaustion during exercise above CP was 15.0 ± 7.0 min and characterized by an inexorable rise in blood lactate and a rise, stabilization (~91% VO(2peak)) and fall in VO(2) (~82% VO(2peak)) prior to exhaustion. Eight out of nine participants completed the 3 min test and their EPs at 90 s (148 ± 29 W) and 180 s (146 ± 30 W) were not different from CP (146 ± 27 W) (P = 0.98). The typical error of estimates for establishing CP using EP at 90 s or 180 s of the 3 min test were 25 W (19.7% CV) and 25 W (19.6% CV), respectively. CP in active adolescence provides a valid landmark for maximal steady-state exercise, although its estimation on an individual level using the 3 min all-out test may be of limited value. VO(2peak)
Abstract.
Author URL.
Armstrong N, Barker AR (2012). New insights in paediatric exercise metabolism.
JOURNAL OF SPORT AND HEALTH SCIENCE,
1(1), 18-26.
Author URL.
Breese BC, Barker AR, Armstrong N, Jones AM, Williams CA (2012). The effect of baseline metabolic rate on pulmonary O₂ uptake kinetics during very heavy intensity exercise in boys and men.
Respir Physiol Neurobiol,
180(2-3), 223-229.
Abstract:
The effect of baseline metabolic rate on pulmonary O₂ uptake kinetics during very heavy intensity exercise in boys and men.
This study tested the hypothesis that pulmonary VO₂ kinetics would be slowed during 'work-to-work' exercise in adults but not in children. Eight boys (mean age=12.5 ± 0.5 years) and nine men completed very heavy step transitions initiated from either 'unloaded' pedalling (U→VH) or unloaded-to-moderate cycling (i.e. U→M to M→VH). The phase II τ was significantly (p
Abstract.
Author URL.
Williams CA, Saynor ZL, Barker AR, Oades PJ (2012). WS16.2 the reliability of maximal cardiopulmonary exercise testing for young cystic fibrosis patients. Journal of Cystic Fibrosis, 11
2011
Barker AR, Bond B, Toman C, Williams CA, Armstrong N (2011). Critical power in adolescents: physiological bases and assessment using all-out exercise. European Journal of Applied Physiology, 1-12.
Armstrong N, Barker AR (2011). Endurance Training and Elite Young Athletes.
Medicine and Sport Science,
56, 59-83.
Abstract:
Endurance Training and Elite Young Athletes.
Endurance training consists of a structured exercise programme that is sustained for a sufficient length of time with sufficient intensity and frequency to induce an improvement in aerobic fitness. Young athletes generally have higher peak oxygen uptakes (peak. 2) than their untrained peers largely due to their greater maximal stroke volumes. Trained young athletes have faster 2 kinetic responses to step changes in exercise intensity but whether this is due to enhanced oxygen delivery or increased oxygen utilization remains to be explored. Blood lactate accumulation in young athletes during submaximal exercise is lower than in untrained youth and this appears to be due to enhanced oxidative function in the active muscles. Few longitudinal endurance training studies of young athletes have been published. Even in the general paediatric population peak. 2 is the only component of aerobic fitness on which there are sufficient data to examine dose-response effects of endurance training. The existence of a maturational threshold below which children are not trainable remains to be proven. The magnitude of training responses is independent of sex. Pre-training peak 2 has a moderate but significant inverse relationship with post-training peak. 2 which suggests that young athletes are likely to experience smaller increases in peak. 2 with further endurance training than untrained youth. Empirical evidence strongly indicates that both trained and untrained young people can benefit from endurance training but the relative intensity of exercise required for optimum benefits is higher than that recommended for adults.
Abstract.
Barker AR, Williams CA, Jones AM, Armstrong N (2011). Establishing maximal oxygen uptake in young people during a ramp cycle test to exhaustion.
British Journal of Sports Medicine,
45(6), 498-503.
Abstract:
Establishing maximal oxygen uptake in young people during a ramp cycle test to exhaustion
Objectives: This study tested the hypotheses that (1) secondary criteria (respiratory exchange ratio (RER), heart rate, blood [lactate]) traditionally used to verify the determination of maximum oxygen uptake (V̇O 2max) in children can result in the acceptance of a 'submaximal'.V̇O2max or falsely reject a 'true' V̇O 2max and (2) the V̇O2peak recorde.d during a ramp test in children is comparable to the V̇O2peak achieved during supramaximal testing. Methods: Thirteen children (9-10 years) completed a ramp cycle test to exhaustion to determine their V̇O2peak. After 15 min of recovery, the participants performed a supramaximal cycle test to exhaustion at 105% of their ramp test peak power. Results: Compared with t.he V̇O2peak during the ramp test, a significantly lower V̇O 2 was recorded at a RER of 1.00 (1.293 litre/min (SD 0.265) vs 1.681 litre/min (SD 0.295), p
Abstract.
Barker AR, Armstrong N (2011). Exercise testing elite young athletes.
Med Sport Sci,
56, 106-125.
Abstract:
Exercise testing elite young athletes.
Children and adolescents are becoming increasingly involved in competitive sport and, as a consequence, are engaging in specialized training with the objective of enhancing their sporting performance. An important aspect of achieving this goal is to ensure young athletes receive appropriate and on-going physiological assessment and support. Moreover, as young athletes require unique consideration (e.g. impact of biological maturity) compared to senior athletes, the challenge is for the exercise physiologist to adopt appropriate methods of assessment. This paper reviews field-and laboratory-based assessment of young athletes' aerobic fitness and performance during maximal intensity exercise. However, as studies of elite young athletes in their sporting environment are limited, the extant sport literature is complemented with data from untrained young people. The most appropriate variables to measure, which methodology and protocol to use, and how best to interpret the results of relevant tests are addressed. Key measurement issues relating to the specificity, validity and reliability of the physiological measures are examined and where possible, sport-specific measures are presented. The unique issues and considerations of providing continued physiological support to young athletes are discussed.
Abstract.
Author URL.
Breese BC, Armstrong N, Barker AR, Williams CA (2011). The effect of pedal rate on pulmonary O2 uptake kinetics during very heavy intensity exercise in trained and untrained teenage boys.
Respir Physiol Neurobiol,
177(2), 149-154.
Abstract:
The effect of pedal rate on pulmonary O2 uptake kinetics during very heavy intensity exercise in trained and untrained teenage boys.
This study tested the hypothesis that the VO2 kinetic response would be slowed in untrained (UT) but not trained (T) teenage participants whilst cycling at 115 rev min(-1) compared to 50 rev min(-1). Eight UT and seven T boys completed two square-wave transitions to very heavy-intensity exercise pedalling at 50 rev min(-1) and 115 rev min(-1). In UT at the higher pedal rate, the phase II VO2 was significantly (P < 0.01) slower (50 rev min(-1): 32 ± 5 vs. 115 rev min(-1): 42 ± 11 s) and the relative VO2 slow component was significantly (P < 0.01) elevated (50 rev min(-1): 10 ± 3 vs. 115 rev min(-1): 16 ± 5%). The phase II VO2 (50 rev min(-1): 26 ± 4 vs. 115 rev min(-1): 22 ± 6s) and relative VO2 slow component (50 rev min(-1): 14 ± 5 vs. 115 rev min(-1): 17 ± 3%) were unaltered by pedal rate in T (P > 0.05). These data are consistent with the notion that VO2 kinetics are influenced by muscle fibre recruitment in youth but this effect is attenuated in endurance trained teenage boys.
Abstract.
Author URL.
2010
Willcocks RJ, Williams CA, Barker AR, Fulford J, Armstrong N (2010). Age- and Sex- Related Differences in Muscle Phosphocreatine and Oxygenation Kinetics during High Intensity Exercise in Adolescents and Adults. Nuclear Magnetic Resonance in Biomedicine
Willcocks RJ, Williams CA, Barker AR, Fulford J, Armstrong N (2010). Age- and sex-related differences in muscle phosphocreatine and oxygenation kinetics during high-intensity exercise in adolescents and adults.
NMR Biomed,
23(6), 569-577.
Abstract:
Age- and sex-related differences in muscle phosphocreatine and oxygenation kinetics during high-intensity exercise in adolescents and adults.
The aim of this investigation was to examine the adaptation of the muscle phosphates (e.g. phosphocreatine (PCr) and ADP) implicated in regulating oxidative phosphorylation, and oxygenation at the onset of high intensity exercise in children and adults. The hypotheses were threefold: primary PCr kinetics would be faster in children than adults; the amplitude of the PCr slow component would be attenuated in children; and the amplitude of the deoxyhaemoglobin/myoglobin (HHb) slow component would be reduced in children. Eleven children (5 girls, 6 boys, 13 +/- 1 years) and 11 adults (5 women, 6 men, 24 +/- 4 years) completed two to four constant work rate exercise tests within a 1.5 T MR scanner. Quadriceps muscle energetics during high intensity exercise were monitored using (31)P-MRS. Muscle oxygenation was monitored using near-infrared spectroscopy. The time constant for the PCr response was not significantly different in boys (31 +/- 10 s), girls (31 +/- 10 s), men (44 +/- 20 s) or women (29 +/- 14 s, main effects: age, p = 0.37, sex, p = 0.25). The amplitude of the PCr slow component relative to end-exercise PCr was not significantly different between children (23 +/- 23%) and adults (17 +/- 13%, p = 0.47). End-exercise [PCr] was significantly lower, and [ADP] higher, in females (18 +/- 4 mM and 53 +/- 16 microM) than males (23 +/- 4 mM, p = 0.02 and 37 +/- 11 microM, p = 0.02), but did not differ with age ([PCr]: p = 0.96, [ADP]: p = 0.72). The mean response time for muscle tissue deoxygenation was significantly faster in children (22 +/- 4 s) than adults (27 +/- 7 s, p = 0.01). The results of this study show that the control of oxidative metabolism at the onset of high intensity exercise is adult-like in 13-year-old children, but that matching of oxygen delivery to extraction is more precise in adults.
Abstract.
Author URL.
Berthoin S, Dupont G, Baquet G (2010). Commentaries on Viewpoint: Do oxidative and anaerobic energy production in exercising muscle change throughout growth and maturation? Manifestations of a common underlying cause. Journal of applied physiology (Bethesda, Md. : 1985), 109(5).
Armstrong N, Barker AR (2010). Endurance training and elite young athletes.
,
56, 59-83.
Abstract:
Endurance training and elite young athletes
© 2011 by S. Karger AG. All rights reserved. Endurance training consists of a structured exercise programme that is sustained for a sufficient length of time with sufficient intensity and frequency to induce an improvement in aerobic fitness. Elite young athletes generally have higher peak oxygen uptakes (peak V O2) than their untrained peers largely due to their greater maximal stroke volumes. Trained young athletes have faster VO2 kinetic responses to step changes in exercise intensity but whether this is due to enhanced oxygen delivery or increased oxygen utilization by the muscles remains to be explored. Blood lactate accumulation in young athletes during submaximal exercise is lower than in untrained youth and this appears to be due to enhanced oxidative function in the active muscles. No well-designed, longitudinal endurance training studies of elite young athletes have been published. Even in the general paediatric population peak V O2 is the only component of aerobic fitness on which there are sufficient data to examine dose-response effects of endurance training. The existence of a maturational threshold below which children are not trainable remains to be proven. The magnitude of training responses is independent of sex. Pre-training peak V O2 has a moderate but significant inverse relationship with post-training peak V O2 which suggests that elite young athletes are likely to experience smaller increases in peak V O2 with further endurance training than untrained youth. Empirical evidence strongly indicates that both trained and untrained young people can benefit from endurance training but the relative intensity of exercise required for optimum benefits is higher than that recommended for adults.
Abstract.
Barker AR, Armstrong N (2010). Exercise Testing Elite Young Athletes. Medicine and Sport Science, 56, 106-125.
Barker AR, Armstrong N (2010). Insights into Development Muscle Metabolism through the Use of 31P-Magnetic Resonance Spectroscopy. Pediatric Exercise Science
Barker AR, Armstrong N (2010). Insights into developmental muscle metabolism through the use of 31P-magnetic resonance spectroscopy: a review.
Pediatr Exerc Sci,
22(3), 350-368.
Abstract:
Insights into developmental muscle metabolism through the use of 31P-magnetic resonance spectroscopy: a review
31)phosphorous-magnetic resonance spectroscopy ((31)P-MRS) has become an extremely valuable technique to investigate changes in muscle metabolism noninvasively and in vivo. The purpose of this article is to critically review how (31)P-MRS has contributed to current understanding of muscle metabolic function in healthy children and adolescents. In addition, an overview of the basic principles of (31)P-MRS and its application to the study of muscle metabolism is provided and discussed in relation to child-specific methodological concerns when using this technique.
Abstract.
Barker AR, Armstrong N (2010). Insights into developmental muscle metabolism through the use of <sup>31</sup>P-magnetic resonance spectroscopy: a review.
Pediatric Exercise Science,
22(3), 350-368.
Abstract:
Insights into developmental muscle metabolism through the use of 31P-magnetic resonance spectroscopy: a review
31phosphorous-magnetic resonance spectroscopy ( 31P-MRS) has become an extremely valuable technique to investigate changes in muscle metabolism noninvasively and in vivo. The purpose of this article is to critically review how 31P-MRS has contributed to current understanding of muscle metabolic function in healthy children and adolescents. In addition, an overview of the basic principles of 31P-MRS and its application to the study of muscle metabolism is provided and discussed in relation to child-specific methodological concerns when using this technique. © 2010 Human Kinetics, Inc.
Abstract.
Breese BC, Williams CA, Barker AR, Weisman JR, Fawkner SG, Armstrong N (2010). Longitudinal Changes in the Oxygen Uptake Kinetic Response to Heavy-Intensity Exercise in 14- to 16-Year-Old Boys (Reprinted from PES, vol 22).
PEDIATRIC EXERCISE SCIENCE,
22(2), 314-325.
Author URL.
Breese BC, Williams CA, Barker AR, Welsman JR, Fawkner SG, Armstrong N (2010). Longitudinal change in the oxygen uptake kinetic response to heavy-intensity exercise in 14- to 16-years-old boys. Pediatr Exerc Sci, 22(2), 314-325.
Breese BC, Williams CA, Barker AR, Welsman JR, Fawker SG, Armstrong N (2010). Longitudinal changes in the oxygen uptake kinetic response to heavy-intensity exercise in 14- to 16-year-old boys. Pediatric Exercise Science, 22(1), 69-80.
Barker AR, Welsman JR, Welford D, Fulford J, Armstrong N (2010). Quadriceps muscle energetics during an incremental test to exhaustion in children and adults. Medicine and Science in Sports and Exercise
Barker AR, Welsman JR, Fulford J, Welford D, Armstrong N (2010). Quadriceps muscle energetics during incremental exercise in children and adults.
Med Sci Sports Exerc,
42(7), 1303-1313.
Abstract:
Quadriceps muscle energetics during incremental exercise in children and adults.
PURPOSE: This study tested the hypothesis that the muscle metabolic responses of 9- to 12-yr-old children and young adults during incremental quadriceps exercise are dependent on age and sex. METHODS: Fifteen boys, 18 girls, 8 men, and 8 women completed a quadriceps step-incremental test to exhaustion inside a magnetic resonance scanner for determination of the muscle metabolic responses using P-magnetic resonance spectroscopy. Quadriceps muscle mass was determined using magnetic resonance imaging scans enabling comparison of metabolic data at a normalized power output. RESULTS: the power output and the energetic state at the Pi/PCr and pH intracellular thresholds (IT) were independent of age and sex. The rate of change in Pi/PCr against power output after the ITPi/PCr (S2) was lower in boys (0.158 +/- 0.089) and girls (0.257 +/- 0.110) compared with men (0.401 +/- 0.114, P < 0.001) and women (0.391 +/- 0.133, P = 0.014), respectively, with sex differences present for children only (P = 0.003). Above the ITpH, S2 was more rapid in the men (-0.041 +/- 0.022, P = 0.003) and girls (-0.030 +/- 0.013, P = 0.011) compared with boys (-0.019 +/- 0.007), with no differences between the girls and the women (-0.035 +/- 0.015, P = 0.479). The increase in Pi/PCr at exhaustion was lower in boys (0.85 +/- 0.38) than that in men (1.86 +/- 0.65, P < 0.001) and in girls (1.78 +/- 1.25) than that in women (4.97 +/- 3.52, P = 0.003), with sex differences in both the child (P = 0.005) and the adult groups (P = 0.019). CONCLUSIONS: During moderate-intensity exercise, muscle metabolism appears adult-like in 9- to 12-yr-old children, although both age- and sex-related differences in the "anaerobic" energy turnover are present during high-intensity exercise.
Abstract.
Author URL.
Barker AR, Breese BC, Willcocks RJ, Williams CA, Armstrong N (2010). The importance of exercise intensity when studying developmental energy metabolism. Journal of Applied Physiology, 109(5), 1565-1566.
Barker AR, Jones AM, Armstrong N (2010). The influence of priming exercise on oxygen uptake, cardiac output, and muscle oxygenation kinetics during very heavy-intensity exercise in 9- to 13-yr-old boys.
J Appl Physiol (1985),
109(2), 491-500.
Abstract:
The influence of priming exercise on oxygen uptake, cardiac output, and muscle oxygenation kinetics during very heavy-intensity exercise in 9- to 13-yr-old boys.
The present study examined the effect of priming exercise on O(2) uptake (Vo(2)) kinetics during subsequent very heavy exercise in eight 9- to 13-yr-old boys. We hypothesised that priming exercise would 1) elevate muscle O(2) delivery prior to the subsequent bout of very heavy exercise, 2) have no effect on the phase II Vo(2) tau, 3) elevate the phase II Vo(2) total amplitude, and 4) reduce the magnitude of the Vo(2) slow component. Each participant completed repeat 6-min bouts of very heavy-intensity cycling exercise separated by 6 min of light pedaling. During the tests Vo(2), muscle oxygenation (near infrared spectroscopy), and cardiac output (Q) (thoracic impedance) were determined. Priming exercise increased baseline muscle oxygenation and elevated Q at baseline and throughout the second exercise bout. The phase II Vo(2) tau was not altered by priming exercise (bout 1: 22 + or - 7 s vs. bout 2: 20 + or - 4 s; P = 0.30). However, the time constant describing the entire Vo(2) response from start to end of exercise was accelerated (bout 1: 43 + or - 8 s vs. bout 2: 36 + or - 5 s; P = 0.002) due to an increased total phase II Vo(2) amplitude (bout 1: 1.73 + or - 0.33 l/min vs. bout 2: 1.80 + or - 0.59 l/min; P = 0.002) and a reduced Vo(2) slow component amplitude (bout 1: 0.18 + or - 0.08 l/min vs. bout 2: 0.12 + or - 0.09 l/min; P = 0.048). These results suggest that phase II Vo(2) kinetics in young boys is principally limited by intrinsic muscle metabolic factors, whereas the Vo(2) total phase II and slow component amplitudes may be O(2) delivery sensitive.
Abstract.
Author URL.
2009
Williams CA, Willcocks RJ, Barker AR, Fulford J, Armstrong N (2009). Muscle Phosphocreatine Kinetics in Children and Adults During High-intensity Exercise. Medicine & Science in Sports & Exercise, 41(5).
Armstrong N, Barker AR (2009). Oxygen uptake kinetics in children and adolescents: a review.
Pediatr Exerc Sci,
21(2), 130-147.
Abstract:
Oxygen uptake kinetics in children and adolescents: a review.
The pulmonary oxygen uptake (pVO2) kinetic response at the onset of exercise provides a noninvasive window into the metabolic activity of the muscle and a valuable means of increasing our understanding of developmental muscle metabolism. However, to date only limited research has been devoted to investigating the pVO2 kinetic response during exercise in children and adolescents. From the rigorous studies that have been conducted, both age- and sex-related differences have been identified. Specifically, children display a faster exponential rise in the phase II pVO2 kinetics, which are purported to reflect the rise in muscle O2 consumption, during moderate, heavy and very heavy intensity exercise compared with adults. Furthermore, for heavy and very heavy exercise, the O2 cost of exercise is higher for the exponential phase and the magnitude of the pVO2 slow component is smaller in young children. Sex-related differences have been identified during heavy, but not moderate exercise, with prepubertal boys displaying a faster exponential phase II pVO2 kinetic response and a smaller pVO2 slow component compared with prepubertal girls. The mechanisms underlying these differences are currently poorly understood, and form the basis for future research in this area. However, it is hypothesized that an age-related modulation of the muscle phosphate feedback controllers to signal an increased rate of oxidative phosphorylation and/or altered muscle fiber type recruitment strategies have the potential to play an important role. Overall, the data support the view that at the onset of exercise children have an enhanced potential for oxidative metabolism in the myocyte compared with adults.
Abstract.
Author URL.
2008
Willcocks RJ, Barker AR, Fulford J, Welford D, Welsman JR, Armstrong N, Williams CA (2008). Kinetics of Phosphocreatine and Deoxyhemoglobin in Children and Adults During High-Intensity Exercise.
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE,
40(5), S20-S20.
Author URL.
Barker AR, Welsman JR, Fulford J, Welford D, Williams CA, Armstrong N (2008). Muscle phosphocreatine and pulmonary oxygen uptake kinetics in children at the onset and offset of moderate intensity exercise.
Eur J Appl Physiol,
102(6), 727-738.
Abstract:
Muscle phosphocreatine and pulmonary oxygen uptake kinetics in children at the onset and offset of moderate intensity exercise.
To further understand the mechanism(s) explaining the faster pulmonary oxygen uptake (p(VO)(2)) kinetics found in children compared to adults, this study examined whether the phase II p(VO)(2) kinetics in children are mechanistically linked to the dynamics of intramuscular PCr, which is known to play a principal role in controlling mitochondrial oxidative phosphorylation during metabolic transitions. On separate days, 18 children completed repeated bouts of moderate intensity constant work-rate exercise for determination of (1) PCr changes every 6 s during prone quadriceps exercise using (31)P-magnetic resonance spectroscopy, and (2) breath by breath changes in p(VO)(2) during upright cycle ergometry. Only subjects (n = 12) with 95% confidence intervals
Abstract.
Author URL.
Barker AR, Welsman JR, Fulford J, Welford D, Armstrong N (2008). Muscle phosphocreatine kinetics in children and adults at the onset and offset of moderate-intensity exercise.
J Appl Physiol (1985),
105(2), 446-456.
Abstract:
Muscle phosphocreatine kinetics in children and adults at the onset and offset of moderate-intensity exercise.
The splitting of muscle phosphocreatine (PCr) plays an integral role in the regulation of muscle O2 utilization during a "step" change in metabolic rate. This study tested the hypothesis that the kinetics of muscle PCr would be faster in children compared with adults both at the onset and offset of moderate-intensity exercise, in concert with the previous demonstration of faster phase II pulmonary O2 uptake kinetics in children. Eighteen peri-pubertal children (8 boys, 10 girls) and 16 adults (8 men, 8 women) completed repeated constant work-rate exercise transitions corresponding to 80% of the Pi/PCr intracellular threshold. The changes in quadriceps [PCr], [Pi], [ADP], and pH were determined every 6 s using 31P-magnetic resonance spectroscopy. No significant (P>0.05) age- or sex-related differences were found in the PCr kinetic time constant at the onset (boys, 21+/-4 s; girls, 24+/-5 s; men, 26+/-9 s; women, 24+/-7 s) or offset (boys, 26+/-5 s; girls, 29+/-7 s; men, 23+/-9 s; women 29+/-7 s) of exercise. Likewise, the estimated theoretical maximal rate of oxidative phosphorylation (Qmax) was independent of age and sex (boys, 1.39+/-0.20 mM/s; girls, 1.32+/-0.32 mM/s; men, 2.36+/-1.18 mM/s; women, 1.51+/-0.53 mM/s). These results are consistent with the notion that the putative phosphate-linked regulation of muscle O2 utilization is fully mature in peri-pubertal children, which may be attributable to a comparable capacity for mitochondrial oxidative phosphorylation in child and adult muscle.
Abstract.
Author URL.
Barker AR, Welsman JR, Fulford J, Welford D, Armstrong N (2008). Quadriceps Muscle Phosphocreatine and Deoxygenation Kinetics in Children and Adults at the Onset of Moderate Intensity Exercise.
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE,
40(5), S20-S20.
Author URL.
Williams CA, Willcocks RJ, Barker AR, Fulford J, Welford D, Welsman JR, Armstrong N (2008). Recovery of Muscle Oxygenation and Phosphocreatine in Children and Adults Following High-Intensity Quadriceps Exercise.
MEDICINE AND SCIENCE IN SPORTS AND EXERCISE,
40(5), S20-S20.
Author URL.
2006
Tolfrey K, Barker A, Thom JM, Morse CI, Narici MV, Batterham AM (2006). Quantification of active muscle mass during experimental exercise - Reply. J APPL PHYSIOL, 101(5), 1535-1535.
Barker A, Welsman J, Welford D, Fulford J, Williams C, Armstrong N (2006). Reliability of 31P-magnetic resonance spectroscopy during an exhaustive incremental exercise test in children.
Eur J Appl Physiol,
98(6), 556-565.
Abstract:
Reliability of 31P-magnetic resonance spectroscopy during an exhaustive incremental exercise test in children.
This study examined the reliability of (31)P-magnetic resonance spectroscopy (MRS) to measure parameters of muscle metabolic function in children. On separate days, 14 children (7 boys and 7 girls) completed three knee-extensor incremental tests to exhaustion inside a whole-body scanner (1.5 T, Phillips). The dynamic changes in the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular muscle pH were resolved every 30 s. Using plots of Pi/PCr and pH against power output (W), intracellular thresholds (ITs) for each variable were determined using both subjective and objective procedures. The IT(Pi/PCr) and IT(pH) were observed subjectively in 93 and 81% of their respective plots, whereas the objective method identified the IT(Pi/PCr) in 88% of the plots. The IT(pH) was undetectable using the objective method. End exercise (END) END(Pi/PCr), END(pH), IT(Pi/PCr) and IT(pH) were examined using typical error statistics expressed as a % coefficient of variation (CV) across all three exercise tests. The CVs for the power output at the subjectively determined IT(Pi/PCr) and IT(pH) were 10.6 and 10.3%, respectively. Objective identification of the IT(Pi/PCr) had a CV of 16.3%. CVs for END(pH) and END(Pi/PCr) were 0.9 and 50.0%, respectively. MRS provides a valuable window into metabolic changes during exercise in children. During knee-extensor exercise to exhaustion, END(pH) and the subjectively determined IT(Pi/PCr) and IT(pH) demonstrate good reliability and thus stable measures for the future study of developmental metabolism. However, the objectively determined IT(Pi/PCr) and END(Pi/PCr) displayed poor reliability.
Abstract.
Author URL.
Barker A, Welsman J, Welford D, Fulford J, Williams C, Armstrong N (2006). Reliability of <sup>31</sup>P-magnetic resonance spectroscopy during an exhaustive incremental exercise test in children.
European Journal of Applied Physiology,
98(6), 556-565.
Abstract:
Reliability of 31P-magnetic resonance spectroscopy during an exhaustive incremental exercise test in children
This study examined the reliability of 31P-magnetic resonance spectroscopy (MRS) to measure parameters of muscle metabolic function in children. On separate days, 14 children (7 boys and 7 girls) completed three knee-extensor incremental tests to exhaustion inside a whole-body scanner (1.5 T, Phillips). The dynamic changes in the ratio of inorganic phosphate to phosphocreatine (Pi/PCr) and intracellular muscle pH were resolved every 30 s. Using plots of Pi/PCr and pH against power output (W), intracellular thresholds (ITs) for each variable were determined using both subjective and objective procedures. The ITPi/PCr and ITpH were observed subjectively in 93 and 81% of their respective plots, whereas the objective method identified the ITPi/PCr in 88% of the plots. The ITpH was undetectable using the objective method. End exercise (END) ENDPi/PCr, ENDpH, ITPi/PCr and ITpH were examined using typical error statistics expressed as a % coefficient of variation (CV) across all three exercise tests. The CVs for the power output at the subjectively determined ITPi/PCr and ITpH were 10.6 and 10.3%, respectively. Objective identification of the ITPi/PCr had a CV of 16.3%. CVs for ENDpH and ENDPi/PCr were 0.9 and 50.0%, respectively. MRS provides a valuable window into metabolic changes during exercise in children. During knee-extensor exercise to exhaustion, ENDpH and the subjectively determined ITPi/PCr and ITpH demonstrate good reliability and thus stable measures for the future study of developmental metabolism. However, the objectively determined ITPi/PCr and ENDPi/PCr displayed poor reliability. © Springer-Verlag 2006.
Abstract.
Tolfrey K, Barker A, Thom JM, Morse CI, Narici MV, Batterham AM (2006). Scaling maximum oxygen uptake using lower leg muscle volume provides further insight into the pitfalls of whole body-mass power laws - Reply.
JOURNAL OF APPLIED PHYSIOLOGY,
101(3), 1007-1007.
Author URL.
Tolfrey K, Barker A, Thom JM, Morse CI, Narici MV, Batterham AM (2006). Scaling of maximal oxygen uptake by lower leg muscle volume in boys and men.
J Appl Physiol (1985),
100(6), 1851-1856.
Abstract:
Scaling of maximal oxygen uptake by lower leg muscle volume in boys and men.
The aim of this study was to critically examine the influence of body size on maximal oxygen uptake (VO2 max) in boys and men using body mass (BM), estimated fat-free mass (FFM), and estimated lower leg muscle volume (Vol) as the separate scaling variables. VO2 max and an in vivo measurement of Vol were assessed in 15 boys and 14 men. The FFM was estimated after percentage body fat had been predicted from population-specific skinfold measurements. By using nonlinear allometric modeling, common body size exponents for BM, FFM, and Vol were calculated. The point estimates for the size exponent (95% confidence interval) from the separate allometric models were: BM 0.79 (0.53-1.06), FFM 1.00 (0.78-1.22), and Vol 0.64 (0.40-0.88). For the boys, substantial residual size correlations were observed for VO2 max/BM0.79 and VO2 max/FFM1.00, indicating that these variables did not correctly partition out the influence of body size. In contrast, scaling by Vol0.64 led to no residual size correlation in boys or men. Scaling by BM is confounded by heterogeneity of body composition and potentially substantial differences in the mass exponent between boys and men. The FFM is precluded as an index of involved musculature because Vol did not represent a constant proportion of FFM [Vol proportional, variantFFM1.45 (95% confidence interval, 1.13-1.77)] in the boys (unlike the men). We conclude that Vol, as an indicator of the involved muscle mass, is the most valid allometric denominator for the scaling of VO2 max in a sample of boys and men heterogeneous for body size and composition.
Abstract.
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