Publications by year
In Press
Brailey G, Metcalf B, Lear R, Price L, Cumming S, Stiles V (In Press). A comparison of the associations between bone health and three different intensities of accelerometer-derived habitual physical activity in children and adolescents: a systematic review. Osteoporosis International
2024
Lear R (2024). Associations of Physical Activity and Vascular Health.
Abstract:
Associations of Physical Activity and Vascular Health
Current public health guidelines recommend adults achieve 150 minutes/week of moderate-vigorous physical activity (PA) to reduce the risk of cardiovascular disease. However, little is known about how PA should be accumulated to provide the greatest protection to the vascular system. The aim of this thesis was to provide the first detailed understanding of associations between PA and vascular health, and in particular, whether the pattern of PA accumulation is important, over and above PA volume.
Chapter 2 describes a systematic review and meta-analysis which characterises the nature and magnitude of associations of PA with vascular health in the existing literature. Chapters 4-6 investigate cross-sectional associations in a large cohort study between PA volume (Chapter 4), the influence of PA patterns between- and within-days (Chapter 5) and the time-of-day of PA (Chapter 6) with indices of vascular health. Chapter 7 describes an experimental study investigating the importance of the proximity of PA prior to post-prandial hyperglycaemia for vascular function.
Principal findings support previous evidence that higher volumes of PA are associated with better vascular heath, and that the association is stronger in those with Type 2 Diabetes Mellitus. This thesis provides new evidence that beyond the overall volume of PA, the pattern in which PA is accumulated is additionally important for both macrovascular and microvascular health. In particular, a PA pattern characterised by lower inter-daily stability, and higher between- and within-day variability may be most beneficial.
This highlights opportunities for future public health and clinical guidance to extend beyond simplistic “more is better” approaches, and additionally provide more options on how to “move differently”. Future prospective studies are needed to confirm the present findings before pattern-based recommendations could be realised. However, this thesis provides a foundation for future research, and challenges current public health guidance which suggests how PA is accumulated is immaterial.
Abstract.
Lear R, Metcalf B, Hillsdon M, Bond B, Koster A, Vandercappellen E, de Galan B, Berendschot TTJM, Houben A, Kooman J, et al (2024). Associations of between- and within-day patterns of physical activity accumulation with arterial stiffness and indices of microvascular health-Evidence from the Maastricht study.
Scand J Med Sci Sports,
34(5).
Abstract:
Associations of between- and within-day patterns of physical activity accumulation with arterial stiffness and indices of microvascular health-Evidence from the Maastricht study.
While physical activity (PA) is understood to promote vascular health, little is known about whether the daily and weekly patterns of PA accumulation associate with vascular health. Accelerometer-derived (activPAL3) 6- or 7-day stepping was analyzed for 6430 participants in the Maastricht Study (50.4% women; 22.4% Type 2 diabetes mellitus (T2DM)). Multivariable regression models examined associations between stepping metrics (average step count, and time spent slower and faster paced stepping) with arterial stiffness (measured as carotid-femoral pulse wave velocity (cfPWV)), and several indices of microvascular health (heat-induced skin hyperemia, retinal vessel reactivity and diameter), adjusting for confounders and moderators. PA pattern metrics were added to the regression models to identify associations with vascular health beyond that of stepping metrics. Analyses were stratified by T2DM status if an interaction effect was present. Average step count and time spent faster paced stepping was associated with better vascular health, and the association was stronger in those with compared to those without T2DM. In fully adjusted models a higher step count inter-daily stability was associated with a higher (worse) cfPWV in those without T2DM (std β = 0.04, p = 0.007) and retinal venular diameter in the whole cohort (std β = 0.07, p = 0.002). A higher within-day variability in faster paced stepping was associated with a lower (worse) heat-induced skin hyperemia in those with T2DM (std β = -0.31, p = 0.008). Above and beyond PA volume, the daily and weekly patterns in which PA was accumulated were additionally associated with improved macro- and microvascular health, which may have implications for the prevention of vascular disease.
Abstract.
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2023
Culverhouse J, Hillsdon M, Metcalf B, Nunns M, Lear R, Brailey G, Pulsford R (2023). Associations between device-measured physical activity and performance-based physical function outcomes in adults: a systematic review and meta-analysis.
BMJ Public Health,
1(1), e100000-e100000.
Abstract:
Associations between device-measured physical activity and performance-based physical function outcomes in adults: a systematic review and meta-analysis
This systematic review and meta-analysis aimed to examine the association between device-measured physical activity (PA) and performance-based measures of physical function (PF). Databases searched included CINAHL, Embase, MEDLINE/PubMed, SPORTDiscus, and Web of Science (last search conducted on November 11, 2022). Observational studies (cross-sectional or prospective) reporting associations between wearable device-measured PA and PF outcomes in non-clinical adults were eligible. Forty-two studies with a pooled sample of 27 276 participants were eligible, with 34 studies reporting a standardised regression coefficient (β) between at least one of four PA measures and one of six PF outcomes. All measures of PA were positively associated with all measures of PF, except for step count with grip strength. Largest associations were seen with lower-body PF tests; gait speed (βs=0.11–0.26), walk tests (βs=0.18–0.41), chair-rise test (βs=0.10–0.26), balance (βs=0.07–0.24) and Timed Up-and-Go (βs=0.10–0.24) all p<0.01. Small or no association was seen with grip strength (βs=0.02–0.07). In observational studies of general adult populations, there were associations between multiple dimensions of PA and a broad range of PF measures. The findings provide provisional support for the use of device measures of movement to remotely monitor people for risk of low PF. Prospective designs are needed to determine the direction of the relationship. Future studies should also explore a broader range of PA metrics beyond simple aggregate measures of time spent at different acceleration values as there is evidence that the temporal distribution of activity is related to health and functional outcomes.
Abstract.
Lear R, Metcalf B, Brailey G, Nunns M, Bond B, Hillsdon M, Pulsford R (2023). Associations of habitual physical activity and carotid-femoral pulse wave velocity; a systematic review and meta-analysis of observational studies.
PLoS One,
18(4).
Abstract:
Associations of habitual physical activity and carotid-femoral pulse wave velocity; a systematic review and meta-analysis of observational studies.
The aim of this review was to understand the association between habitual physical activity (hPA) and carotid-femoral pulse wave velocity (cfPWV) in an ostensibly healthy adult population. Searches were performed in MEDLINE Web of Science, SPORTDiscus and CINAHL databases published up to 01/01/2022 (PROSPERO, Registration No: CRD42017067159). Observational English-language studies assessing the relationship between cfPWV and hPA (measured via self-report or device-based measures) were considered for inclusion in a narrative synthesis. Studies were excluded if studying specific disease. Studies were further included in pooled analyses where a standardised association statistic for continuous hPA and cfPWV was available. 29 studies were included in narrative synthesis, of which 18 studies provided sufficient data for pooled analyses, totalling 15,573 participants. A weak, significant, negative correlation between hPA and cfPWV was observed; partial r = -0.08 95%CI [-0.15, -0.01]; P = 0.045. Heterogeneity was high (I2 = 94.5% P
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2019
Lear R, O'Leary M, O'Brien Andersen L, Holt CC, Stensvold CR, van der Giezen M, Bowtell JL (2019). Tart Cherry Concentrate Does Not Alter the Gut Microbiome, Glycaemic Control or Systemic Inflammation in a Middle-Aged Population.
Nutrients,
11(5).
Abstract:
Tart Cherry Concentrate Does Not Alter the Gut Microbiome, Glycaemic Control or Systemic Inflammation in a Middle-Aged Population.
Limited evidence suggests that the consumption of polyphenols may improve glycaemic control and insulin sensitivity. The gut microbiome produces phenolic metabolites and increases their bioavailability. A handful of studies have suggested that polyphenol consumption alters gut microbiome composition. There are no data available investigating such effects in polyphenol-rich Montmorency cherry (MC) supplementation. A total of 28 participants (aged 40-60 years) were randomized to receive daily MC or glucose and energy-matched placebo supplementation for 4 wk. Faecal and blood samples were obtained at baseline and at 4 wk. There was no clear effect of supplementation on glucose handling (Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and Gutt indices), although the Matsuda index decreased significantly in the MC group post-supplementation, reflecting an increase in serum insulin concentration. Contrastingly, placebo, but not MC supplementation induced a 6% increase in the Oral Glucose Insulin Sensitivity (OGIS) estimate of glucose clearance. Serum IL-6 and C reactive protein were unaltered by either supplement. The faecal bacterial microbiome was sequenced; species richness and diversity were unchanged by MC or placebo and no significant correlation existed between changes in Bacteroides and Faecalibacterium abundance and any index of insulin sensitivity. Therefore, 4 weeks of MC supplementation did not alter the gut microbiome, glycaemic control or systemic concentrations of IL-6 and CRP in a middle-aged population.
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