The purpose of this study was to test the validity and the accuracy of estimating maximal oxygen uptake (VO2max) from ratings of perceived exertion (RPE), during sub-maximal tests in competitive cyclists. Twelve competitive cyclists performed a graded exercise test (GXT) and a test with randomised workloads (TRW) on a cycle ergometer. Oxygen uptake (VO2) and RPE were measured at 150, 200, 250 and 300 Watts (W) during both tests, and actual VO2max was also determined at the end of the GXT. Individual linear regressions between VO2 and RPE were extrapolated to RPE 19 in order to estimate VO2max from each test. Actual and estimated VO2max from GXT and TRW were not significantly different (65.0 ± 6.9, 68.3 ± 8.8 and 73.1 ± 12.0 ml.kg-1.min-110 , respectively; p > 0.05). The estimated VO2max were significantly correlated to actual VO2max whatever the test (p

This study examined the time course of changes in the blood volume and oxygenation of accessory respiratory (RM) and locomotor (LM) muscles, and the interrelationships of changes in these parameters during maximal incremental intermittent exercise in 15 non-endurance-trained active men. Blood volume and oxygenation of serratus anterior and of vastus lateralis were measured simultaneously by near-infrared spectroscopy. The respiratory compensation point (RCP), and the breakpoints where abrupt changes were apparent in RM and LM blood volume and oxygenation versus time were identified. During exercise, the decreases in RM and LM oxygenation were accentuated in the vicinity of the RCP. This was concomitant with a reduction in LM, but not RM, blood volume. The time at which the RCP and the breakpoints in RM and LM blood volume and oxygenation were detected (70.2-75.0% exercise time) did not differ, and were inter-correlated (r=0.56 to 0.95). Moreover, the rate of the accelerated fall of oxygenation in LM was correlated with that of the decline in blood volume in that area (r=0.73), and with that of the accelerated fall of oxygenation in RM (r=0.71). The results suggest that the high ventilatory demand, which occurs naturally during intense intermittent exercise in non-endurance-trained individuals, may precipitate an accelerated fall in the RM oxygenation, concomitant with a reduction in LM blood volume and an accentuated decline in LM oxygenation. Such responses are likely to occur onward above the RCP during the intermittent exercise.

A number of pictorial ratings of perceived exertion (RPE) scales have been developed to assess perceived exertion during various modes of exercise in children. Most of the pictorial scales depict a figure at varying stages of exertion on either a horizontal line or a linear gradient with verbal descriptors. The purpose of this study was to assess the perceived exertion response to an intermittent graded exercise test (GXT) in 14 healthy, 7-8 year-old children, using the Eston-Parfitt (E-P) Ratings of Perceived Exertion (RPE) scale and a marble dropping task described previously (Eston et al. 2009, Psychophysiology, 46, 843-851). The E-P Scale depicts a character at various stages of exertion on a progressively increasing incline with verbal descriptors abridged from the Children’s Effort Rating Table. For the GXT, the treadmill was set at a constant speed of 8 km•h-1 for each 1-min stage, initially at 0% gradient and incremented by 2% for each stage until exhaustion. Stages were separated by 1-min recovery periods during which the child reported the RPE and dropped a number of marbles into a bowl (≤50) to provide an alternative means of RPE. For the E-P scale and the marble dropping task, the relationships between the RPE and work rate were best described as linear (R2 = 0.96) and curvilinear (R2 = 0.94), respectively. This study further suggests that individual respiratory-metabolic cues (oxygen uptake, heart rate, minute ventilation) may significantly influence the overall RPE to varying degrees in young children. The E-P scale provides an intuitively meaningful and valid means of quantifying the overall perception of exertion in young, healthy children during treadmill running. The marble dropping task is a useful secondary measure of perceived exertion, which provides further insight into the nature of the perceived exertion response to exercise in young children.

We tested the hypothesis that exercise-induced muscle damage (EIMD) would increase the ventilatory response to incremental/ramp cycle exercise (lower the gas exchange threshold), without altering the blood lactate profile thereby dissociating the gas exchange and lactate thresholds. Ten physically active men completed maximal incremental cycle tests before (pre) and 48 h after (post) performing eccentric exercise comprising 100 squats. Pulmonary gas exchange was measured breath-by-breath and finger-tip blood sampled at 1-min intervals for blood [La] determination. The gas exchange threshold occurred at a lower work rate (pre, 136 ± 27 W; post, 105 ± 19 W, P< 0.05) and. (pre, 1.58 + 0.26; post, 1.41 + 0.14 l.min-1, P< 0.05) after eccentric exercise. However, the lactate threshold occurred at a similar work rate (pre, 161 ± 19 W; post, 158 ± 22 W, P> 0.05) and. (pre, 1.90 ± 0.20 l.min-1; post, 1.88 ± 0.15 l.min-1, P > 0.05) after eccentric exercise. These findings demonstrate that EIMD dissociates the response to incremental/ramp exercise from the [La] response indicating that may be controlled by additional or altered neurogenic stimuli following eccentric exercise. Thus, due consideration of prior eccentric exercise should be made when using the gas exchange threshold to provide a non-invasive estimation of the lactate threshold.

Objective: to assess the accuracy of predicting. O2max from a Graded Exercise Test (GXT) and a ramp exercise test during arm exercise in able-bodied and paraplegic persons using Rating of Perceived Exertion (RPE).
Design:. Each participant performed a GXT (started at 30 W and increased by 15 W every 2 min) and a ramp exercise test (started at 0 W and increased by 15 W.min-1).
Setting: Facilities of physiology laboratory at universities.
Participants:. Thirteen able-bodied men (27.2 ± 4.3 y) and 12 men with paraplegia (31.1 ± 5.7 y). Six of the paraplegic persons had flaccid paralysis as a results of poliomyelitis infection, whereas the other 6 had complete spinal cord injury and T6 or below.
Intervention: not applicable.
Main Outcome Measures: Prediction of. O2max by extrapolating submaximal. O2 & RPE values to RPE 20 on Borg’s 6-20 RPE scale.
Results: This study showed a very strong linear relationship between RPE and. O2 during the GXT and the ramp test for able-bodied (R2 ≥. 95 & R2 ≥. 96, respectively) and paraplegic individuals (R2 ≥. 96 & R2 ≥. 95, respectively). There was no significant difference between measured and predicted. O2max from RPEs before and including RPE 13, 15 & 17 during the GXT for paraplegic individuals (P > 0.05). For the able-bodied participants, there was no significant difference between measured and predicted. O2max from RPEs before and including RPE 15 and 17 during the ramp exercise test (P > 0.05).
Conclusion: the GXT provided acceptable prediction of. O2max for paraplegic individuals and the ramp test provided acceptable prediction of. O2max for able-bodied individuals.

This study examined the hypothesis that chronic (training) and acute (warm-up) loaded ventilatory activities applied to the inspiratory muscles (IM) in an integrated manner would augment the training volume of an interval running program. This in turn would result in additional improvement in the maximum performance of the Yo-Yo intermittent recovery test in comparison with interval training alone. Eighteen male nonprofessional athletes were allocated to either an inspiratory muscle loading (IML) group or control group. Both groups participated in a 6-week interval running program consisting of 3-4 workouts (1-3 sets of various repetitions of selected distance [100-2,400 m] per workout) per week. For the IML group, 4-week IM training (30 inspiratory efforts at 50% maximal static inspiratory pressure [P0] per set, 2 sets.d, 6 d.wk) was applied before the interval program. Specific IM warm-up (2 sets of 30 inspiratory efforts at 40% P0) was performed before each workout of the program. For the control group, neither IML was applied. In comparison with the control group, the interval training volume as indicated by the repeatability of running bouts at high intensity was approximately 27% greater in the IML group. Greater increase in the maximum performance of the Yo-Yo test (control: 16.9 +/- 5.5%; IML: 30.7 +/- 4.7% baseline value) was also observed after training. The enhanced exercise performance was partly attributable to the greater reductions in the sensation of breathlessness and whole-body metabolic stress during the Yo-Yo test. These findings show that the combination of chronic and acute IML into a high-intensity interval running program is a beneficial training strategy for enhancing the tolerance to high-intensity intermittent bouts of running.

This study assessed the effect of distance feedback on athletic performance, physiological and perceptual markers and the pacing strategies utilised during treadmill exercise. Thirteen men completed four self-paced 6 km treadmill time trials with either accurate (AF), inaccurate, or no distance feedback (NF). Inaccurate time trials involved participants receiving premature (PF) or delayed (DF) feedback, prior to or following the completion of each kilometre. The provision of accurate or inaccurate distance feedback (PF, DF) did not moderate the completion time or the rate of change in the Ratings of Perceived Exertion (P >. 05). However, completion times were significantly slower when exercising with no distance feedback (P <. 001). Heart rate (HR), oxygen uptake ( O2) and running velocity all increased during the conditions (P <. 001). A significantly lower. O2 (up to 7 %) and HR (up to 6 %) was observed during NF. This study has demonstrated that athletic performance and perceptual and physiological responses are unaffected by inaccurate distance feedback. However, the study indicates that individuals may exercise at a lower metabolic intensity when running without distance feedback.

Strategies to manage the symptoms of exercise-induced muscle damage are widespread, though are often based on anecdotal evidence. The aim of this study was to determine the efficacy of a combination of manual massage and compressive clothing and compressive clothing individually as recovery strategies following muscle damage. Thirty-two female volunteers completed 100 plyometric drop jumps, and were randomly assigned to a passive recovery (n = 17), combined treatment (n = 7) or compression treatment group (n = 8). Indices of muscle damage (perceived soreness, creatine kinase activity, isokinetic muscle strength, squat jump and countermovement jump performance) were assessed immediately before, and 1, 24, 48, 72, and 96 h following plyometric exercise. The compression treatment group wore compressive tights for 12 h following damage and the combined treatment group received a 30-min massage immediately after damaging exercise, and wore compression stockings for the following 11.5 h. Plyometric exercise had a significant effect on all indices of muscle damage (p < 0.05). The treatments significantly reduced decrements in isokinetic muscle strength, squat jump performance and countermovement jump performance, and reduced the level of perceived soreness in comparison with the passive recovery group (p < 0.05). The addition of sports massage to compression following muscle damage did not improve performance recovery, with recovery trends being similar in both treatment groups. The treatment combination of massage and compression significantly moderated perceived soreness at 48 and 72 h following plyometric exercise (p < 0.05) in comparison with the passive recovery or compression alone treatment. The results indicate that the use of lower limb compression and a combined treatment of manual massage with lower limb compression are effective recovery strategies following exercise-induced muscle damage. Minimal performance differences between treatments were observed, although the combination treatment may be beneficial in controlling perceived soreness.

This study aimed to investigate the efficacy of
lower limb compression as a recovery strategy following exercise-induced muscle damage (EIMD). Seventeen female volunteers completed 10 9 10 plyometric drop jumps from a 0.6-m box to induce muscle damage. Participants were randomly allocated to a passive recovery (n = 9) or a compression treatment (n = 8) group. Treatment
group volunteers wore full leg compression stockings for 12 h immediately following damaging exercise. Passive recovery group participants had no intervention. Indirect
indices of muscle damage (muscle soreness, creatine kinase activity, knee extensor concentric strength, and vertical
jump performance) were assessed prior to and 1, 24, 48, 72,and 96 h following plyometric exercise. Plyometric exercise had a significant effect (p B 0.05) on all indices of
muscle damage. The compression treatment reduced
decrements in countermovement jump performance (passive recovery 88.1 ± 2.8% vs. treatment 95.2 ± 2.9% of pre-exercise), squat jump performance (82.3 ± 1.9% vs. 94.5 ± 2%), and knee extensor strength loss (81.6 ± 3% vs. 93 ± 3.2%), and reduced muscle soreness (4.0 ± 0.23
vs. 2.4 ± 0.24), but had no significant effect on creatine kinase activity. The results indicate that compression clothing is an effective recovery strategy following exercise-induced muscle damage.

The purpose of this study was to develop a
simple, convenient and indirect method for predicting peak oxygen uptake (VO2peak) from a sub-maximal graded exercise test (GXT), in obese women. Thirty obese women performed GXT to volitional exhaustion. During GXT, oxygen uptake and the power at RPE 15 (PRPE 15) were measured, and VO2peak was determined. Following. assessment of the relationships between VO2peak and PRPE 15, age, height and mass were made available in a stepwise multiple regression analysis with VO2peak as the dependent variable. This study suggests that age and PRPE 15 elicited during a sub-maximal GXT provides
a reasonably accurate prediction of _V O2peak in obese women.

This study assessed the relationship between Rating of Perceived Exertion (RPE) and time to exhaustion during arm cranking exercise while exercising at two different constant-load exercise intensities in able-bodied and paraplegic individuals. The second aim of this study was to assess the rate of change in the RPE between the two different constant-load exercise intensities in absolute and relative terms. Ten able-bodied men and 10 paraplegic men performed four exercise tests: 1) a ramp exercise test (started at 0 W and increased by 15 W.min-1), 2) a graded exercise test (started at 30 W and increased by 15 W every 2 minutes); these tests were performed in counterbalanced order, 3) a constant-load exercise test equal to 50% delta (i.e. the difference between the gas exchange threshold and peak power output (Δ)), 4) a constant-load exercise test equal to 70% Δ; these tests were also performed in counterbalanced order. There was a strong linear relationship between the RPE and time to exhaustion (R2 ≥ 0.88) irrespective of exercise intensity and participants’ group. As expected, the rate of change in the RPE was significantly greater during 70% Δ compared to 50% Δ when the RPE was regressed against absolute time regardless of group. However, differences in the rate of change in the RPE were removed when the RPE was regressed against proportion of time, irrespective of group. These findings have important implications for predicting time to exhaustion while exercising at constant-load exercise intensity during arm cranking in able-bodied and paraplegic individuals.

PURPOSE:: to examine the validity of perception-based intensity regulation during handcycling exercise. METHODS:: Eight spinal cord-injured (T11 incomplete to T4 complete) participants completed an incremental exercise test followed by a V O2peak test using a sports hand bike. Subsequently, two 20-min exercise tests were completed at an individualized power output (PO) at moderate and vigorous intensities (50% and 70% of V O2peak, respectively). On a separate occasion, participants were instructed to produce and maintain a workload equivalent to the average RPE for the 20-min imposed condition in a counterbalanced order. The V O2 and blood lactate concentration [BLa] were measured every 10 min, and HR and PO were measured at 1-min intervals. RESULTS:: There were no differences in average V O2, percent V O2peak, HR, PO, and [BLa] between the imposed PO conditions and RPE-regulated trials of either exercise intensity. Although PO increased slightly during the moderate-intensity RPE-regulated trial (P < 0.04), it remained relatively constant in the vigorous RPE-regulated trial. However, there was a tendency for PO to be slightly higher (P = 0.07) in the vigorous RPE-regulated trial. CONCLUSIONS:: These data suggest that RPE is effective in controlling moderate and vigorous intensities throughout a 20-min handcycling exercise session for SCI participants.

OBJECTIVE: to investigate the strength of the relationship between ratings of perceived exertion (RPE) and oxygen uptake (Vo(2)), heart rate, ventilation (Ve) and power output (PO) during an arm-crank ramped exercise test to volitional exhaustion in men and women who differed in physical status. DESIGN: Each participant completed an arm-crank ramp exercise test to volitional exhaustion. PO was increased by 15 W.min(-1) and 6 W.min(-1) for men and women able-bodied participants, respectively; for the poliomyelitis participants, 9 W.min(-1) and 6 W.min(-1) increments were used for men and women, respectively. SETTING: Laboratory facilities at a university. PARTICIPANTS: Able-bodied participants (n=16; 9 men, 7 women) and participants with poliomyelitis (n=15, 8 men, 7 women) volunteered for the study. MAIN OUTCOME MEASURES: Strength of the relationship (R(2) values) between RPE and Vo(2), heart rate, Ve and PO. RESULTS: There were significantly higher values for maximum Vo(2) and maximum PO for able-bodied men compared with their counterparts with poliomyelitis (P.05). Similar results were observed for the women who were able-bodied as well as for the women who had poliomyelitis (P>.05). The relationships between heart rate and RPE and Ve and RPE for able-bodied patients and patients with poliomyelitis were similar (R(2)>.87). The relationship between Vo(2) and RPE was stronger in the able-bodied participants compared wih the participants with poliomyelitis, regardless of sex (P.05). CONCLUSIONS: RPE is strongly related to physiologic markers of exercise intensity during arm exercise, irrespective of sex or participant's poliomyelitis status.

Purpose: the study aims were: 1) to assess the technical reliability and validity of the GENEA
using a mechanical shaker, 2) to perform a GENEA value calibration to develop thresholds for
sedentary, light, moderate, and vigorous intensity physical activity, and 3) to compare the intensity classification of the GENEA with two widely used accelerometers. Methods: 47
GENEAs were attached to a shaker and vertically accelerated generating 15 conditions of
varying acceleration and/or frequency. Reliability was calculated using standard deviation and intra- and inter-instrument coefficient of variation, while validity was assessed via Pearson correlation with the shaker acceleration as the criterion. Next, 60 adults wore a GENEA on each wrist and on the waist (alongside an Actigraph and RT3 accelerometer) while completing 10-12 activity tasks. A portable metabolic gas analyzer provided the criterion measure of physical activity. Analyses involved the use of Pearson correlations to establish criterion and concurrent validity and ROC curves to establish intensity cut points. Results: the GENEA demonstrated excellent technical reliability (CVintra=1.4% CVinter=2.1%) and validity (r=0.98; p

This study examined the effect of exerciseinduced
muscle damage (EIMD) on ventilatory and perceived
exertion responses to cycle exercise. Ten healthy, physically active men cycled for 6 min at moderate intensity and to exhaustion at severe intensity before and 48 h after eccentric exercise (100 squats with a load corresponding
to 70% of body mass). Changes in ventilation
and ratings of perceived exertion (RPE) were calculated for each individual and expressed against time (moderate and severe exercise) and as a percentage of time to exhaustion (severe exercise). Ventilation increased during moderate
exercise at 48 h ( _VE; 34.5 ± 5.0 to 36.3 ± 3.8 l min-1, P

This study evaluated the effects of exercise-induced muscle damage (EIMD) on fixed-load cycling and 5-min time-trial performance. Seven recreational athletes performed two submaximal fixed-load exercise bouts followed by a 5-min time-trial before, 48 and 168 h following 100 counter-movement jumps. Measurements of V(O)(2) heart rate, RER and blood lactate concentration remained unchanged during the fixed-load bouts following jumping exercise. However, VE and VE/VO2 increased (P < 0.05) at 48 h. RPE values were higher at 48 h as were the ratio of RPE:HR and RPE:VO2 (P < 0.05). In the time-trial, mean VO2 peak power output, mean power output, distance covered and post exercise blood lactate were lower at 48 h (P < 0.05). RPE remained unchanged between trials. These findings indicate that the ventilatory equivalent for oxygen and perceived exertion at submaximal work rates are increased 48 h following eccentric exercise. Furthermore, EIMD increases perceived exertion and impairs performance during a 5-min all-out effort.

Abstract
Objective. Spontaneous and transitory movement patterns are characteristic of children. The aim of this study was to explore the relationship between short, frequent activity bouts and children’s health. Methods. Physical activity was recorded every 2 s by accelerometry (ActiGraph GT1M) for seven days in 47 boys (age 8 10 years). Summary activity measures and
activity pattern characteristics (frequency, intensity and duration of ]4 s [short] and ]5 min [long] bouts of ]light []LIGHT], ]moderate []MOD], ]vigorous []VIG], and ]hard []HARD] intensity activity) were recorded. Microvascular function was assessed using laser Doppler perfusion imaging as the forearm skin blood flow response to the iontophoretic application of acetylcholine (endothelial dependent vasodilator) and sodium nitroprusside (endothelial independent vasodilator) at rest and following maximal exercise. Waist circumference, resting blood pressure and aerobic
fitness (/V˙O2peak) were measured. Results. The intensity of short and long ]LIGHT bouts and the frequency of short and long]MOD bouts were correlated with waist circumference (r. 0.42 to. 0.52, pB0.01) and V˙O2peak (r 0.42 to 0.47,
pB0.01), but not when scaled for lean body mass. The frequency of short and long ]LIGHT bouts were associated with change in endothelial function from rest to post-exercise (r 0.34 to 0.55, pB0.05). No relationships were evident between blood pressure and activity. Conclusion. The relationship between the frequency of short bouts (]4 s) of activity and health
was as strong as relationships identified between longer bouts (]5 min) and health. This is encouraging as sporadic intermittent activity is characteristic of children’s activity pattern.

This study assessed the validity of the Eston-Parfitt (E-P) curvilinear Ratings of Perceived Exertion (RPE) Scale and a novel marble quantity task to provide estimates of perceived exertion during cycle ergometry. Fifteen children aged 7–8
years performed a discontinuous incremental graded-exercise test, and reported exertional ratings at the end of each minute. Significant increases in physiological and perceptual data were observed with increasing work rate. The
relationship between work rate and marbles was curvilinear (mean R25.94), supporting the theoretical justification for the E-P Scale. Strong linear (R25.93) and curvilinear (R25.94) relationships between RPE from the E-P Scale
and work rate confirmed the robustness of the E-P Scale. Valid exertional ratings may be obtained using the E-P Scale with young children. The novel marble quantity task offers an alternative method of deriving perceived exertion responses in children.

The One Repetition Maximum (1-RM) test is commonly used to assess strength. However, direct assessments of 1-RM are time
consuming and unsafe for novice lifters. Whilst various equations exist to predict 1-RM, there is limited research on the validity of these equations. The purpose of this study was to
assess the validity of using sub-maximal ratings of perceived exertion (RPE) to predict 1-RM in young adults, using the Borg 6-20 RPE Scale. Twenty healthy participants (ten male (Mean ±
SD, 20.8 ± 0.6 y, 75.7 ± 9.3 kg, 1.8 ± 0.07 m) and ten female (20.3 ± 0.7 y, 68.4 ± 10.0 kg, 1.68 ± 0.03 m)) completed two trials involving resistance exercises for both the upper and lower
body. In the first trial the 1-RM for the ilateral biceps curl (BC)and the bilateral knee extension (KE) were determined for each participant. In the second trial, participants performed blinded repetitions which were equivalent to 20, 40 and 60 % of 1-RM
for both exercises. The RPE was recorded immediately after two repetitions had been completed at each intensity. The order of
intensity of the repetitions was randomly assigned with participants wearing blindfolds to exclude the possibility of predetermined
judgments about load and RPE. Individual RPE
recorded at each intensity was subjected to linear regression analysis and the line of best fit was extrapolated to RPE 20 to predict 1-RM in both exercises. There was no significant difference (p > 0.05) between the 1-RM predicted from RPE 20 and measured 1-RM for both exercises for the men and women. Measured and predicted values for men were 46.0 ± 4.6 and 45.2 ± 6.1 kg for biceps curl, and 46.3 ± 3.8 and 43.0 ± 7.1 kg
for knee extension, respectively. Measured and predicted values for women were 18.6 ± 5.7 and 19.3 ± 5.6 kg for biceps curl,and 25.5 ± 9.6 and 27.2 ± 12.6 kg for knee extension, respectively.
Pearson product-moment correlation coefficients between actual and predicted 1-RM for the BC and KE were 0.97 and 0.92, respectively. These results provide evidence that submaximal ratings of perceived exertion can be used to provide
reasonably accurate estimates of 1-RM in young and active men and women.

Perceived exertion involves the interplay of afferent feedback from cardio-respiratory,
metabolic and thermal stimuli and efferent feed-forward mechanisms to enable an individual to evaluate how hard or easy an exercise task feels. It is moderated by a) psychological factors—among which are cognition, memory and
understanding of the task and b) situational factors—which include knowledge of the duration and temporal characteristics of the task (e.g. continuous, intermittent or spasmodic) and knowledge of the target distance or total amount of work to be completed. On the basis of the above, it should be apparent that assessment of
how accurately a child can rate perceived exertion (RPE) remains a significant challenge. This editorial will elaborate on what I perceive to be some of the challenges for future studies.

Unaccustomed eccentric exercise has a profound impact on muscle structure and function. However, it is not known whether associated microvascular dysfunction disrupts the matching of O2 delivery (Qo2) to O2 utilization (Vo2). Near-infrared spectroscopy (NIRS) was used to test the hypothesis that eccentric exercise-induced muscle damage would elevate the muscle Qo2:Vo2 ratio during severe-intensity exercise while preserving the speed of the Vo2 kinetics at exercise onset. Nine physically active men completed "step" tests to severe-intensity exercise from an unloaded baseline on a cycle ergometer before (Pre) and 48 h after (Post) eccentric exercise (100 squats with a load corresponding to 70% of body mass). NIRS and breath-by-breath pulmonary Vo2 were measured continuously during the exercise tests and subsequently modeled using standard nonlinear regression techniques. There were no changes in phase II pulmonary Vo2 kinetics following the onset of exercise (time constant: Pre, 25 +/- 4 s; Post, 24 +/- 2 s; amplitude: Pre, 2.36 +/- 0.23 l/min; Post, 2.37 +/- 0.23 l/min; all P > 0.05). However, the primary (Pre, 14 +/- 3 s; Post, 19 +/- 3 s) and overall (Pre, 16 +/- 4 s; Post, 21 +/- 4 s) mean response time of the [HHb] response was significantly slower following eccentric exercise (P < 0.05). The slower [HHb] kinetics observed following eccentric exercise is consistent with an increased Qo2:Vo2 ratio during transitions to severe-intensity exercise. We propose that unchanged primary phase Vo2 kinetics are associated with an elevated Qo2:Vo2 ratio that preserves blood-myocyte O2 flux.

OBJECTIVE: to characterize the pattern of activity in boys and girls across weekdays and weekend days. METHODS: Physical activity was recorded every 2 s by uniaxial accelerometry in 84 children, aged 9-11 years, for up to four weekdays and two weekend days. Activity bouts (>or= 4 s and >or= 5 min) greater than light (>or= LIGHT), moderate (>or= MOD) and vigorous (>or= VIG) intensity were recorded. The study took place in the South-West of England in 2007. RESULTS: the mean duration of activity bouts decreased as intensity increased from 11.0+/-1.3 s for >or= LIGHT activity to 6.1+/-1.0 s for >or= VIG activity. The frequency, duration and intensity of bouts were greater in boys than girls, and the frequency and duration of bouts were greater on weekdays than weekend days. Girls accumulated more activity sporadically than boys, whereas boys accumulated more activity in >or= 5-min bouts. CONCLUSION: Sex differences and weekday/weekend differences in activity were largely due to the intensity of the most frequent bouts of activity and frequency of the most intense bouts. Information regarding the pattern of children's habitual activity can be used to inform activity interventions and assess the aspects of the activity pattern that are related to health.

The ratings of perceived exertion are a widely accepted measure of quantifying, monitoring and regulating exercise intensity. A critical review of the perceived exertion literature since 2000 provides a useful insight into the concepts and themes that have featured prominently in the literature. In this regard, five main themes of enquiry concerning perceived exertion have emerged. These include child-specific rating scaled;, pictorial scales for adults, self-regulation and the efficacy of using the RPE for predicting maximal oxygen uptake, observations that the RPE scales with time or distance remaining in open- and closed-loop exercise tasks, and the influence of carbohydrate and caffeine ingestion on the ratings of perceived exertion. We provide a critical review of these developments and reflect on their relative contributions to knowledge, their potential practical applications and the questions which remain for future research on perceived exertion in adults and children.

Motive8 is a health and fitness company that provides in-school PE/sport provision. The primary aim of this study was to assess the quantity and quality of physical activity during Motive8 PE lessons compared to PE lessons taught by the school PE specialist. A secondary aim was to assess whether PE lessons impact on daily activity levels. Physical activity was measured for 2 weeks in 19 children, aged 10-11 years, using accelerometry. In week 1, half of the children undertook a normal week of lessons, including two School PE lessons (football-based and dance-based); the other half also followed their normal timetable, except that Motive8 led their PE lessons. In week 2, this was reversed. Motive8 classes provided 20.5 +/- 3.8 minutes of moderate and 7.9 +/- 2.6 minutes of vigorous activity This was greater than the 15.9 +/- 6.1 minutes of moderate and 5.1 +/- 3.8 minutes of vigorous activity experienced in the School PE lessons (p < 0.005). Seventy-five percent of children achieved 22 minutes of moderate to vigorous activity in Motive8 PE lessons, compared with the 9 minutes of moderate to vigorous activity achieved by 75% of children in School PE classes. Days containing football classes contained fewer minutes of moderate activity than days containing dance classes or no PE (football, 46.4 +/- 14.6 minutes; dance, 51.8 +/- 15.4 minutes; no PE, 50.7 +/- 10.5 minutes; p < 0.05). In conclusion, physical activity during Motive8 lessons was more consistent between children than in School PE lessons, reflecting increased physical activity in the least active children. PE lessons had little impact on overall daily physical activity.

The purpose of this study was to assess the validity of predicting the maximal oxygen uptake (VO2(max)) of sedentary men from sub-maximal VO2 values obtained during a perceptually regulated exercise test. Thirteen healthy, sedentary males aged 29-52 years completed five graded exercise tests on a cycle ergometer. The first and fifth test involved a graded exercise test to determine VO2(max). The two maximal graded exercise tests were separated by three sub-maximal graded exercise tests, perceptually regulated at 3-min RPE intensities of 9, 11, 13, 15, and 17 on the Borg ratings of perceived exertion (RPE) scale, in that order. After confirmation that individual linear regression models provided the most appropriate fit to the data, the regression lines for the perceptual ranges 9-17, 9-15, and 11-17 were extrapolated to RPE 20 to predict VO2(max). There were no significant differences between VO2(max) values from the graded exercise tests (mean 43.9 ml x kg(-1) x min(-1), s = 6.3) and predicted VO2(max) values for the perceptual ranges 9-17 (40.7 ml x kg(-1) x min(-1), s = 2.2) and RPE 11-17 (42.5 ml x kg(-1) x min(-1), s = 2.3) across the three trials. The predicted VO2(max) from the perceptual range 9-15 was significantly lower (P < 0.05) (37.7 ml x kg(-1) x min(-1), s = 2.3). The intra-class correlation coefficients between actual and predicted VO2(max) for RPE 9-17 and RPE 11-17 across trials ranged from 0.80 to 0.87. Limits of agreement analysis on actual and predicted VO2 values (bias +/- 1.96 x S(diff)) were 3.4 ml x kg(-1) x min(-1) (+/- 10.7), 2.4 ml x kg(-1) x min(-1) (+/- 9.9), and 3.7 ml x kg(-1) x min(-1) (+/- 12.8) (trials 1, 2, and 3, respectively) of RPE range 9-17. Results suggest that a sub-maximal, perceptually guided graded exercise test provides acceptable estimates of VO2(max) in young to middle-aged sedentary males.

The effects of inspiratory muscle (IM) training on maximal 20 m shuttle run performance (Ex) during Yo-Yo intermittent recovery test and on the physiological and perceptual responses to the running test were examined. Thirty men were randomly allocated to 1 of 3 groups. The experimental group underwent a 6 week pressure threshold IM training program by performing 30 inspiratory efforts twice daily, 6 d/week, against a load equivalent to 50% maximal static inspiratory pressure. The placebo group performed the same training procedure but with a minimal inspiratory load. The control group received no training. In post-intervention assessments, IM function was enhanced by >30% in the experimental group. The Ex was improved by 16.3% +/- 3.9%, while the rate of increase in intensity of breathlessness (RPB/4i) was reduced by 11.0% +/- 6.2%. Further, the whole-body metabolic stress reflected by the accumulations of plasma ammonia, uric acid, and blood lactate during the Yo-Yo test at the same absolute intensity was attenuated. For the control and placebo groups, no significant change in these variables was observed. In comparison with previous observations that the reduced RPB/4i resulting from IM warm-up was the major reason for improved Ex, the reduced RPB/4i resulting from the IM training program was lower despite the greater enhancement of IM function, whereas improvement in Ex was similar. Such findings suggest that although both IM training and warm-up improve the tolerance of intense intermittent exercise, the underlying mechanisms may be different.

The purpose of this study was to determine the effects of plyometric exercise on unilateral balance performance. Nine healthy adults performed baseline measurements on the dominant limb that consisted of: a 20-s unilateral stability test on a tilt balance board, where a higher stability index represented deterioration in balance performance; isokinetic plantar flexion torque at 0.52 and 3.14 rad s(-1); muscle soreness in the calf region; and resting plantar flexion angle. Plyometric exercise consisted of 200 counter-movement jumps designed to elicit symptoms of muscle damage, after which baseline measurements were repeated at 30 min, 24, 48, and 72 h. Perceived muscle soreness of the calf region increased significantly following the plyometric exercise protocol (F(4,32) = 17.24, P < 0.01). Peak torque was significantly reduced after the plyometric exercise protocol (F(4,32) = 7.49, P < 0.05), with greater loss of force at the lower angular velocity (F(4,32) = 3.46, P < 0.05), while resting plantar flexion angle was not significantly altered compared with baseline values (P > 0.05). The stability index was significantly increased (F(4,32) = 3.10, P < 0.05) above baseline (mean 2.3, s = 0.3) at 24 h (3.3, s = 0.4), after which values recovered. These results indicate that there is a latent impairment of balance performance following a bout of plyometric exercise, which has implications for both the use of skill-based activities and for increased injury risk following high-intensity plyometric training.

The purpose of this study was to assess whether maximal oxygen uptake (V.O(2 max)) could be predicted from submaximal ratings of perceived exertion (RPE) elicited during the multistage fitness test (MFT). Eleven female volunteers completed three maximal exercise tests in random order; the MFT, a simulated MFT on a motorized treadmill and a graded exercise test to volitional exhaustion (GXT), also on a motorized treadmill. RPE values were recorded at the end of each 1 min stage in all three tests. Oxygen consumption (VO(2)) was recorded continuously during the treadmill tests. Measured V.O(2 max) values from the GXT and simulated MFT were not significantly different (48.2 and 47.5 ml/kg/min, respectively), but they were significantly higher than V.O(2 max) values predicted by the MFT (41.2 ml/kg/min, p

This study assessed the relationship of the rating of perceived exertion (RPE) with heart rate and pacing strategy during competitive running races of differing distance and course elevation. Nine men and women competed in a 7-mile road race (7-MR) and the Great West Run half marathon (GWR; 13.1 miles). Heart rate, split mile time, and RPE were recorded throughout the races. The RPE was regressed against time and %time to complete the 7-MR and GWR. Although the rate of increase in RPE was greater in the 7-MR, there were no differences when expressed against %time (inferring that the brain uses a scalar timing mechanism). As the course elevation, distance, pacing strategy, and heart rate response varied between conditions, this study has provided evidence that the perceptual response may have distinct temporal characteristics during distance running. The results provide further evidence that RPE scales with the proportion of exercise time that remains.

Exercise-induced muscle damage (EIMD) is characterized by loss of strength, increase in muscle stiffness, swelling, and soreness'. The aim of this study was to assess the effects of flexibility training of the hamstring muscle group on symptoms of EIMD. Fourteen males (mean standard deviation: age = 20.6 +/- 0.8 years; mass = 77.3 +/- 10.4 kg; height = 1.77 +/- 0.05 m) were randomly assigned to a 5-week flexibility (proprioceptive neuromuscular facilitation [PNF]) training or control group. Pre- and post-measures of peak static muscle force at knee joint angles representing decreasing muscle lengths of the hamstrings (25 deg, 30 deg, 40 deg, 80 deg) and flexibility were taken. Flexibility increased significantly following PNF flexibility training (pre-test = 19.4 +/- 6.2 cm, post-test = 26.6 +/- 6.9 cm), whereas it stayed constant in the control group (pre-test = 16.0 +/- 9.3 cm, post-test = 16.7 cm). Both groups underwent-a damaging exercise protocol incorporating six sets of 10 isokinetic eccentric contractions of the hamstrings. Measurements of isometric strength, flexibility, and perceived soreness were recorded prior to and 1, 24, 48 and 72 hours after damage. There was a tendency for the PNF group to recover from strength loss earlier at longer muscle lengths (25 deg, p = 0.06 30 deg, p = 0.05), but not at shorter muscle lengths. There was no evidence of a protective effect of PNF training on flexibility and soreness. In conclusion, an increase in flexibility of the hamstring muscle group led to some protection from strength loss at long muscle lengths following EIMD.

Neuromuscular performance capabilities, including those measured by evoked responses, may be adversely affected by fatigue; however, the capability of the neuromuscular system to initiate muscle force rapidly under these circumstances is yet to be established. Sex-differences in the acute responses of neuromuscular performance to exercise stress may be linked to evidence that females are much more vulnerable to anterior cruciate ligament injury than males. Optimal functioning of the knee flexors is paramount to the dynamic stabilisation of the knee joint, therefore the aim of this investigation was to examine the effects of acute maximal intensity fatiguing exercise on the voluntary and magnetically-evoked electromechanical delay in the knee flexors of males and females. Knee flexor volitional and magnetically-evoked neuromuscular performance was assessed in seven male and nine females prior to and immediately after: (1) an intervention condition comprising a fatigue trial of 30-s maximal static exercise of the knee flexors, (2) a control condition consisting of no exercise. The results showed that the fatigue intervention was associated with a substantive reduction in volitional peak force that was greater in males compared to females (15.0, 10.2%, respectively, P < 0.01) and impairment to volitional electromechanical delay in females exclusively (19.3%, P < 0.05). Similar improvements in magnetically-evoked electromechanical delay in males and females following fatigue (21%, P < 0.001), however, may suggest a vital facilitatory mechanism to overcome the effects of impaired voluntary capabilities, and a faster neuromuscular response that can be deployed during critical times to protect the joint system.

PURPOSE: Studies have reported strong linear relationships between accelerometer output and walking/running speeds up to 10 km x h(-1). However, ActiGraph uniaxial accelerometer counts plateau at higher speeds. The aim of this study was to determine the relationships of triaxial accelerometry, uniaxial accelerometry, and pedometry with speed and step frequency (SF) across a range of walking and running speeds. METHODS: Nine male runners wore two ActiGraph uniaxial accelerometers, two RT3 triaxial accelerometers (all set at a 1-s epoch), and two Yamax pedometers. Each participant walked for 60 s at 4 and 6 km x h(-1), ran for 60 s at 10, 12, 14, 16, and 18 km x h(-1), and ran for 30 s at 20, 22, 24, and 26 km x h(-1). Step frequency was recorded by a visual count. RESULTS: ActiGraph counts peaked at 10 km x h(-10 (2.5-3.0 Hz SF) and declined thereafter (r=0.02, P>0.05). After correction for frequency-dependent filtering, output plateaued at 10 km x h(-1) but did not decline (r=0.77, P 10 km x h(-1) (r=0.86, P0.96, P

This study assessed the relationship between differentiated ratings of perceived exertion (RPE) and heart rate with oxygen uptake (VO2) during two graded exercise tests (GXT) to exhaustion on a cycle ergometer in 49 men and women (19-50 years) of high and low fitness. The study also assessed whether sub-maximal RPE values elicited during the GXTs could provide appropriate estimates of maximal aerobic power (VO2max) Peripheral RPE (RPEP) was higher than overall RPE (RPEO) at exhaustion in both groups (P0.05). However, the correlation for RPEP and VO2 was higher for women compared to men (0.98 and 0.96, respectively, P

The purpose of this study was to evaluate, the validity and reliability of the Cart and Load Effort Rating(CALER) and Bug and Bag Effort (BABE) rating scales for intra- and intermodal regulation, of effort production in a triple repeated, randomized, intermittent production paradigm. Thirty boys and girls (age, 9.8 +/- 1.5 years; height, 1.39 +/- 0.08 m: weight, 31.6 +/- 5.80 kg) volunteered to participate in the study and were split into two groups (a CALER group and a BABE group). Each group completed six effort production trials using their allocated scales; three stepping and three-cycling. Effort production levels were set at 3, 5 and 8 for each scale. The children had 2 minutes at each intensity to request an increase or decrease in load (either in the backpack or on the bike) to achieve the effort production level set before continuing at that intensity for an additional minute. Heart rate was recorded at the end of each 3-minute period. Analysis of variance was used to examine the validity of the scales, and intraclass correlation, limits of agreement, and coefficient of variation were used to examine the reliability of the scales. The results indicated that both scales were valid and reliable and that they could be used interchangeably-the CALER scale in a stepping mode and the BABE scale in a cycling mode.

The purpose of this study was to assess the effects of muscle-damaging exercise on the time to peak power during maximal intensity cycling and drop jump performance. Nineteen subjects were randomly assigned to a treatment (n = 10, age 22.6 +/- 2.8 years, body mass 70.7 +/- 12.9 kg, stature 1.76 +/- 0.10 m) or control group (n = 9, age 20.8 +/- 2.5 years, body mass 74.2 +/- 10.2 kg, stature 1.76 +/- 0.07 m) and randomly performed a 10-second cycle ergometer sprint, against a load corresponding to 0.70 N.m.kg(-1) for males and 0. 67 N.m.kg(-1) for females, and a drop jump from a height of 50 cm. Indirect markers of muscle damage (perceived muscle soreness and isokinetic knee extensor torque at 60 and 360 deg.s(-1)) were also assessed. All measures were taken before and at 24, 48, 72 and 168 hours following a plyometric exercise protocol comprised of 10 x 10 maximal countermovement jumps. Repeated measures ANOVA showed significant interactions of time by group on all dependent measures (p

The accurate and reliable assessment of physical activity is necessary for any research study where physical activity is either an outcome measure or an intervention. The aim of this review is to examine the use of objective measurement techniques for the assessment and interpretation of children's physical activity. Accurate measurement of children's activity is challenging, as the activity is characteristically sporadic and intermittent, consisting of frequent, short bouts. Objective measures of physical activity include heart rate telemetry, pedometry and accelerometry, and each of these methods has strengths and limitations. Heart rate is suited to the measurement of sustained periods of moderate and vigorous activity, pedometry provides a valid measure of total activity, and accelerometry provides a valid measure of total activity as well as the pattern and intensity of activity. As the weaknesses of heart rate and accelerometry for the assessment of activity are not inter-correlated, a combination of the two methods may be more accurate than either method alone. Recent evidence suggests that the Actiheart, an integrated accelerometer and heart rate unit, provides a more accurate prediction of children's energy expenditure than either heart rate or accelerometry alone. However, the cost of the Actiheart is prohibitive for large-scale studies. The pedometer is recommended when only the total amount of physical activity is of interest. When the intensity or the pattern of activity is of interest, accelerometry is the recommended measurement tool.

The purpose of this study was to assess the validity of predicting maximal oxygen uptake [V(.-)((O)(2)(max))] from sub-maximal V(.-)((O)(2)) values elicited during perceptually regulated exercise tests of 2- and 4-min duration. Nineteen physically active men and women (age range 19-23 years) volunteered to participate in two graded exercise tests to volitional exhaustion to measure V(.-)((O)(2)(max)) [V(.-)((O)(2)(max))(GXT)], at the beginning and end of a 2-week period, and four incremental, perceptually regulated tests to predict [V(.-)((O)(2)(max))] in the intervening period. Effort production tests comprised 2 x 2-min and 2 x 4-min bouts on a cycle ergometer, perceptually regulated at intensities of 9, 11, 13, 15 and 17 on the Borg 6-20 rating of perceived (RPE) scale, in that order. Individual linear relationships between RPE and V(.-)((O)(2) for RPE ranges of 9-17, 11-17 and 9-15 were extrapolated to RPE 20 to predict [V(.-)((O)(2)(max))]. The prediction of [V(.-)((O)(2)(max))] was not moderated by gender. Although, [V(.-)((O)(2)(max))] estimated from RPE 9-17 of trial 1 of the 2-min protocol was significantly lower (P < 0.05) than [V(.-)((O)(2)(max))(GXT)], and V(.-)((O)(2)(max)) predicted from the 4-min trials, the V(.-)((O)(2)(max)) predicted from trial 2 of the 2-min protocol was a more accurate prediction of [V(.-)((O)(2)(max))(GXT)], across all trials. The intraclass correlation coefficient (R) was also higher between [V(.-)((O)(2)(max))(GXT)], and [V(.-)((O)(2)(max))] predicted from trial 2 of the 2-min protocol compared to both trials in the 4-min protocol (R = 0.95, 0.88 and 0.79, respectively). Similar results were observed for RPE ranges 9-15 and 11-17. Results suggest that a sub-maximal, perceptually guided, graded exercise protocol, particularly of a 2-min duration, provides acceptable estimates of maximal aerobic power, which are not moderated by gender.

Accelerometers record total physical activity and time spent at different intensities. Pedometers indicate total activity only. The aim of this study was to assess the relationship between pedometer counts and attainment of > or = 60 min of moderate activity. Thirty-four children, ages 8-10 years, wore a Tritrac accelerometer and Yamax pedometer. Published recommendations of steps per day were compared to attainment of > or = 60 min moderate activity. Boys who accumulated 13,000 steps.d(-1) and girls who accumulated 12,000 steps.d(-1) engaged in > or = 60 min moderate activity. However, 23% of boys and 15% of girls did not reach the pedometer thresholds but did engage in > or = 60 min moderate activity. In conclusion, these pedometer thresholds provide a reasonable estimation when assessment of physical activity intensity is not possible.

The purpose of this study was to compare symptoms of exercise-induced muscle damage after an initial and repeated bout of plyometric exercise in men and boys. Ten boys (9-10 yr) and 10 men (20-29 yr) completed two bouts of eight sets of 10 plyometric jumps, 2 wk apart. Perceived soreness (0-10, visual analog scale), isometric strength of the quadriceps at six knee flexion angles, and countermovement jump and squat jump height were assessed before and at 30 min, 24 h, 48 h, and 72 h after each bout. All variables followed the expected patterns of change in men, with soreness peaking at 24-48 h (5.8 +/- 1.7) and decrements in muscle function peaking at 30 min after the first bout (73-85% of baseline scores). Symptoms remained for 72 h after the first bout in men. In boys, symptoms were much less severe and peaked at 30 min (visual analog scale = 2.1 +/- 1.8, functional decrements 87-92% of baseline) and, with the exception of soreness, returned to baseline after 24 h. After the second bout of plyometric exercise, the level of soreness and decrements in countermovement jump, squat jump, and isometric strength were lower, although the effect was stronger in men, in all cases. The results of this study suggest that although children may experience symptoms of muscle damage after intensive plyometric exercise, they are much less severe. A prior bout of plyometric exercise also appears to provide children with some protection from soreness after a subsequent bout of plyometric exercise. Explanations for milder symptoms of exercise-induced muscle damage in children include greater flexibility leading to less overextension of sarcomeres during eccentric exercise, fewer fast-twitch muscle fibers, and greater and perhaps more varied habitual physical activity patterns.

OBJECTIVE: to investigate the relationship of percent body fat (%fat), assessed by dual energy-X-ray absorptiometry (DXA) or a four-compartment model, with upper body and lower limb skinfolds. DESIGN: Cross-sectional design involving forward stepwise and hierarchical multiple regression analyses to assess the relationship of %fat with skinfolds and a combination of four commonly used upper body skinfolds (biceps, triceps, subscapular and iliac crest) with the calf and thigh skinfolds. SETTING: University research laboratory. SUBJECTS: in all, 31 females, mean age 20.9 (+/-2.0) y, and 21 males, mean age 22.3 (+/-5.5) y volunteered for this study, which was approved by the Ethics Committee of the School of Sport, Health and Exercise Sciences, University of Wales, Bangor. MEASUREMENTS: %fat from DXA in both groups, and %fat from a four-compartment (water, bone mineral mass, fat and residual) model (%fat4C) in females only. Skinfolds were measured at the abdomen, iliac crest, biceps, triceps, subscapular, calf and thigh. RESULTS: all skinfolds were positively associated with DXA estimates of %fat (P < 0.01). In males and females, the thigh skinfold had the highest correlation with %fat. This was also observed when %fat4C was used as the criterion in females. Stepwise multiple regression analysis using %fatDXA as the criterion selected the thigh (R(2) = 0.82), calf (R(2) change 0.04) and iliac crest (R(2) change = 0.03) for females, and the thigh (R(2) = 0.79), iliac crest (R(2) change = 0.11) and abdomen (R(2) change = 0.03) for males (all P < 0.01). When %fat4C was used as the criterion in the females, only the thigh was selected as a significant predictor (R(2) = 0.76). Independent prediction factors were created from the sum of biceps, triceps, subscapular and iliac crest (sigma4skf) and from the sum of the thigh and calf (sigmathigh + calf). These factors were then entered into a hierarchical multiple linear regression analysis to predict percent fat. Order of entry was varied to allow the assessment of unique variance accounted for by each predictor. The sum of the thigh and calf explained more variance in %fatDXA than that explained by the sigma4skf alone, irrespective of the order of entry in both males and females. This was also observed when %fat4C was used as the criterion in the females. CONCLUSIONS: the results of this study confirm that lower body skinfolds are highly related to percent body fat in fit and healthy young men and women, and uphold current recommendations by the British Olympic Association to include the thigh skinfold with sigma4skf. Conventional use of the sigma4skf to estimate percent body fat is significantly enhanced by the inclusion of the thigh and calf skinfolds, either independently or in combination. In this group of males and females, the sum of the thigh and calf skinfolds accounted for the most variance in percent fat.

Exercise-induced muscle damage (EIMD) is a common occurrence following activities with a high eccentric component. Alterations to the torque-velocity relationship following EIMD would appear to have serious implications for athletic performance, particularly as they relate to impairment of maximal intensity exercise. However, this has been studied infrequently. The purpose of this study was to assess the effects of EIMD on maximal intermittent sprint performance. Ten male participants (age 22.4 +/- 3.2 years, height 178.6 +/- 5.2 cm, mass 80.6 +/- 10.7 kg) performed 10 x 6 s cycle ergometer sprints, interspersed with 24 s recovery against a load corresponding to 0.10 kp/kg and 10 x 10 m sprints from a standing start, each with 12 s active (walking) recovery. All variables were measured immediately before and at 30 min, 24, 48 and 72 h following a plyometric exercise protocol comprising of 10 x 10 maximal counter movement jumps. Repeated measures ANOVA showed significant changes over time (all P

The purpose of this study was to assess the validity of predicting maximal oxygen uptake(VO(2max)) from sub-maximal VO(2) values elicited during a perceptually-regulated exercise test. We hypothesised that the strong relationship between the ratings of perceived exertion (RPE) and VO(2) would enable VO(2max) to be predicted and that this would improve with practice. Ten male volunteers performed a graded exercise test (GXT) to establish VO(2max) followed by three sub-maximal RPE production protocols on a cycle ergometer, each separated by a period of 48 h. The perceptually-regulated trials were conducted at intensities of 9, 11, 13, 15 and 17 on the RPE scale, in that order. VO(2) and HR were measured continuously and recorded at the end of each 4 min stage. Individual's RPE values yielded correlations in the range 0.92-0.99 across the three production trials. There were no significant differences between measured VO(2max) (48.8 ml.kg(-1).min(-1)) and predicted VO(2) max values (47.3, 48.6 and 49.9 ml.kg(-1).min(-1), for trials 1, 2 and 3, respectively) when VO(2) max was predicted from RPE values of 9-17. The same was observed when VO(2max) was predicted using RPE 9-15. Limits of agreement (LoA) analysis on actual and predicted VO(2max) values (from RPE 9-17) were (bias+/-1.96xSDdiff) 1.5+/-7.3, 0.2+/-4.9 and -1.2+/-5.8 ml.kg(-1).min(-1), for trials 1, 2 and 3, respectively. Corresponding LoA values for actual and predicted VO(2max) (from RPE 9-15) were 5.4+/-11.3, 4.4+/-8.7 and 2.3+/-8.4 ml.kg(-1).min(-1), respectively. The data suggest that a sub-maximal, perceptually-guided, graded exercise protocol can provide acceptable estimates of maximal aerobic power, which are further improved with practice in fit young males.

The purpose of this study was to assess the interactive effects of habitual physical activity (total and vigorous intensity) and calcium intake on bone mineral content (BMC) in prepubertal boys and girls. Seventy-six children, aged 8-11 yr, wore accelerometers for up to 7 days to assess activity. Calcium intake was estimated by a 4-day weighted food diary. BMC and areal density (bone mineral density) were measured at the total body, proximal femur, and femoral neck by using dual-energy X-ray absorptiometry. Moderated regression analyses were used to assess the contributions of physical activity (total and vigorous) and calcium intake to BMC, residualized for bone area and body mass. Interactive effects of vigorous activity (> or =6 metabolic equivalents) and calcium intake were found at the total body in boys (b = 2.90 x 10(-3)) and in girls (b = 6.58 x 10(-3)) and at the proximal femur (b = 9.87 x 10(-5)) and femoral neck (b = 2.29 x 10(-5); where b is the regression coefficient from final equation) in boys only; residualized BMC was high only if both vigorous activity and calcium intake were high. There were no interactive effects of total activity and calcium intake. This study provides evidence for synergistic action of habitual vigorous activity and calcium intake on bone mass in children. Recommendations for optimizing bone mass should reflect this synergism.

Exercise-induced muscle damage is a well documented phenomenon particularly resulting from eccentric exercise. When eccentric exercise is unaccustomed or is performed with an increased intensity or duration, the symptoms associated with muscle damage are a common outcome and are particularly associated with participation in athletic activity. Muscle damage results in an immediate and prolonged reduction in muscle function, most notably a reduction in force-generating capacity, which has been quantified in human studies through isometric and dynamic isokinetic testing modalities. Investigations of the torque-angular velocity relationship have failed to reveal a consistent pattern of change, with inconsistent reports of functional change being dependent on the muscle action and/or angular velocity of movement. The consequences of damage on dynamic, multi-joint, sport-specific movements would appear more pertinent with regard to athletic performance, but this aspect of muscle function has been studied less often. Reductions in the ability to generate power output during single-joint movements as well as during cycling and vertical jump movements have been documented. In addition, muscle damage has been observed to increase the physiological demand of endurance exercise and to increase thermal strain during exercise in the heat. The aims of this review are to summarise the functional decrements associated with exercise-induced muscle damage, relate these decrements to theoretical views regarding underlying mechanisms (i.e. sarcomere disruption, impaired excitation-contraction coupling, preferential fibre type damage, and impaired muscle metabolism), and finally to discuss the potential impact of muscle damage on athletic performance.

OBJECTIVES: to evaluate the reliability and validity of measures taken during the Chester step test (CST) used to predict VO(2)max and prescribe subsequent exercise. METHODS: the CST was performed twice on separate days by 7 males and 6 females aged 22.4 (SD 4.6) years. Heart rate (HR), ratings of perceived exertion (RPE), and oxygen uptake (VO(2)) were measured at each stage of the CST. RESULTS: RPE, HR, and actual VO(2) were the same at each stage for both trials but each of these measures was significantly different between CST stages (p50% VO(2)max reliably represents the recommended intensity for developing cardiorespiratory fitness, but only when a practice trial of the CST is first performed.

PURPOSE: the aims of this study were to assess and compare the validity of the RT3 accelerometer for the assessment of physical activity in boys and men, to compare RT3 and Tritrac accelerometer counts, and to determine count cut-off values for moderate (> or =3 < 6 METs) and vigorous (> or =6 METs) activity. METHODS: Nineteen boys (age: 9.5 +/- 0.8 yr) and 15 men (age: 20.7 +/- 1.4 yr) walked and ran on a treadmill, kicked a ball to and fro, played hopscotch, and sat quietly. An RT3 was worn on the right hip; boys also wore a Tritrac on the left hip. Oxygen consumption was expressed as a ratio of body mass raised to the power of 0.75 (S VO2). RESULTS: RT3 counts correlated significantly with S VO2 in boys (r = 0.87, P < 0.01) and men (r = 0.85, P < 0.01). However, during treadmill activities, RT3 counts were significantly higher for boys (P < 0.05). RT3 counts corresponding to "moderate" and "vigorous" activity were similar for boys and men for all activities (moderate = 970.2 for boys and 984.0 for men; vigorous = 2333.0 for boys and 2340.8 for men) but approximately 400 counts lower in men when only treadmill activities were considered. Tritrac counts correlated significantly with S VO2 in boys (r = 0.87, P < 0.01), but were significantly lower than RT3 counts across most activities (P < 0.05). CONCLUSIONS: the RT3 accelerometer is a good measure of physical activity for boys and men. However, moderate and vigorous intensity count thresholds differ for boys and men when the predominant activities are walking and running. RT3 counts are significantly higher than Tritrac counts for a number of activities. These findings have implications when comparing activity counts between studies using the different instruments.

Exercise-induced muscle damage is a well documented phenomenon that often follows unaccustomed and sustained metabolically demanding activities. This is a well researched, but poorly understood area, including the actual mechanisms involved in the muscle damage and repair cycle. An integrated model of muscle damage has been proposed by Armstrong and is generally accepted. A more recent aspect of exercise-induced muscle damage to be investigated is the potential of estrogen to have a protective effect against skeletal muscle damage. Estrogen has been demonstrated to have a potent antioxidant capacity that plays a protective role in cardiac muscle, but whether this antioxidant capacity has the ability to protect skeletal muscle is not fully understood. In both human and rat studies, females have been shown to have lower creatine kinase (CK) activity following both eccentric and sustained exercise compared with males. As CK is often used as an indirect marker of muscle damage, it has been suggested that female muscle may sustain less damage. However, these findings may be more indicative of the membrane stabilising effect of estrogen as some studies have shown no histological differences in male and female muscle following a damaging protocol. More recently, investigations into the potential effect of estrogen on muscle damage have explored the possible role that estrogen may play in the inflammatory response following muscle damage. In light of these studies, it may be suggested that if estrogen inhibits the vital inflammatory response process associated with the muscle damage and repair cycle, it has a negative role in restoring normal muscle function after muscle damage has occurred. This review is presented in two sections: firstly, the processes involved in the muscle damage and repair cycle are reviewed; and secondly, the possible effects that estrogen has upon these processes and muscle damage in general is discussed. The muscle damage and repair cycle is presented within a model, with particular emphasis on areas that are important to understanding the potential effect that estrogen has upon these processes.

A well-documented observation after eccentric exercise is a reduction in maximal voluntary force. However, little is known about the ability to maintain maximal isometric force or generate and maintain dynamic peak power. These aspects of muscle function were studied in seven participants (5 males, 2 females). Knee extensor isometric strength and rate of fatigue were assessed by a sustained 60 s maximal voluntary contraction at 80 degrees and 40 degrees knee flexion, corresponding to an optimal and a shortened muscle length, respectively. Dynamic peak power and rate of fatigue were assessed during a 30 s Wingate cycle test. Plasma creatine kinase was measured from a fingertip blood sample. These variables were measured before, 1 h after and 1, 2, 3 and 7 days after 100 repetitions of the eccentric phase of the barbell squat exercise (10 sets x 10 reps at 80% concentric one-repetition maximum). Eccentric exercise resulted in elevations in creatine kinase activity above baseline (274+/-109 U x l(-1); mean +/- s(x)) after 1 h (506+/-116 U x l(-1), P < 0.05) and 1 day (808+/-117 U x l(-1), P < 0.05). Isometric strength was reduced (P < 0.05) for 7 days (35% at 1 h, 5% at day 7) and the rate of fatigue was lower (P < 0.05) for 3 days at 80 degrees and for 1 day at 40 degrees. Wingate peak power was reduced to a lesser extent (P < 0.05) than isometric strength at 1 h (13%) and, although the time course of recovery was equal, the two variables differed in their pattern of recovery. Eccentrically exercised muscle was characterized by an inability to generate high force and power, but an improved ability to maintain force and power. Such functional outcomes are consistent with the proposition that type II fibres are selectively recruited or damaged during eccentric exercise.

The aim of this study was to investigate the relationship between habitual physical activity and body fatness in Hong Kong Chinese children. Fifty children aged 8-11 yrs wore a uniaxial accelerometer for 7 days to determine physical activity levels. The sum of seven skinfolds was used to estimate body fatness. Activity counts summed over 1 day (299384+/-140427, mean+/-SD) were similar to activity counts recorded in previous studies. Activity correlated significantly negatively with sum of skinfolds in boys (r = -50, N = 24, P <. 05) but not girls. In conclusion this study supports a negative relationship between physical activity and body fatness in Hong Kong Chinese boys.

This study aimed to determine the relationship between bone mineral content, habitual physical activity, and calcium intake in children. Fifty-seven children, aged 8-11 years, wore pedometers for seven days to assess activity. Calcium intake was estimated by a 4-day food diary. Bone mineral content (BMC) and areal density (BMD) were measured at the total proximal femur and femoral neck using dual energy X-ray absorptiometry. Regression analysis was used to assess contributions of physical activity and calcium intake to BMC, residualized for bone area and body mass. Physical activity explained 11.6% of the variance in residualized BMC at the proximal femur and 14.3% at the femoral neck (p < 0.05). Calcium intake added to the variance explained at the proximal femur only (9.8%, p < 0.05). This study provides evidence for an association between BMC and habitual physical activity.

In this study, we assessed the effect of exercise-induced muscle damage on knee extensor muscle strength during isometric, concentric and eccentric actions at 1.57 rad x s(-1) and vertical jump performance under conditions of squat jump, countermovement jump and drop jump. The eight participants (5 males, 3 females) were aged 29.5+/-7.1 years (mean +/- s). These variables, together with plasma creatine kinase (CK), were measured before, 1 h after and 1, 2, 3, 4 and 7 days after a bout of muscle damaging exercise: 100 barbell squats (10 sets x 10 repetitions at 70% body mass load). Strength was reduced for 4 days (P< 0.05) but no significant differences (P> 0.05) were apparent in the magnitude or rate of recovery of strength between isometric, concentric and eccentric muscle actions. The overall decline in vertical jump performance was dependent on jump method: squat jump performance was affected to a greater extent than countermovement (91.6+/-1.1% vs 95.2+/-1.3% of pre-exercise values, P< 0.05) and drop jump (95.2+/-1.4%, P< 0.05) performance. Creatine kinase was elevated (P < 0.05) above baseline 1 h after exercise, peaked on day 1 and remained significantly elevated on days 2 and 3. Strength loss after exercise-induced muscle damage was independent of the muscle action being performed. However, the impairment of muscle function was attenuated when the stretch-shortening cycle was used in vertical jumping performance.

Angle-specific isometric strength and angular velocity-specific concentric strength of the knee extensors were studied in eight subjects (5 males and 3 females) following a bout of muscular damaging exercise. One hundred maximal voluntary eccentric contractions of the knee extensors were performed in the prone position through a range of motion from 40 degrees to 140 degrees (0 degrees = full extension) at 1.57 rads(-1). Isometric peak torque was measured whilst seated at 10 degrees and 80 degrees knee flexion, corresponding to short and optimal muscle length, respectively. Isokinetic concentric peak torque was measured at 0.52 and 3.14 rad x s(-1). Plasma creatine kinase (CK) activity was also measured from a fingertip blood sample. These measures were taken before, immediately after and on days 1, 2, 4, and 7 following the eccentric exercise. The eccentric exercise protocol resuited in a greater relative loss of strength (P< 0.05) at short muscle length (76.3 +/- 2.5% of pre-exercise values) compared to optimal length (82.1 +/- 2.7%). There were no differences in the relative strength loss between isometric strength at optimal length and isokinetic concentric strength at 0.52 and 3.14 rad x s(-1). CK activity was significantly elevated above baseline at days 4 (P < 0.01) and 7 (P < 0.01). The greater relative strength loss at short muscle length appeared to persist throughout the seven-day testing period and provides indirect evidence of a shift in the angle-torque relationship towards longer muscle lengths. The results lend partial support to the popping sarcomere hypothesis of muscle damage, but could also be explained by an impairment of activation at short muscle lengths.

This study assessed the effects of stride length on symptoms of exercise-induced muscle damage after downhill running and whether the extent of the symptoms sustained in a repeated bout of downhill running are influenced by stride length manipulation in the first bout. Eighteen males aged 21.1 +/- 0.6 years (mean +/- s) were allocated to one of three groups for bout one: preferred stride frequency, overstride and understride. Bout two was performed 2 weeks later at the participants' preferred stride frequency. Maximal isometric force and perceived muscle soreness were assessed pre-test and 30 min, 24, 48 and 72 h post-exercise for each downhill run. Three-factor analyses of variance with repeated measures on time and bout were used for analysis. Results revealed a three-way interaction for soreness (F8,60 = 3.56, P < 0.05) and relative isometric strength (F5.0,37.8 = 3.2, P < 0.05). Post-hoc analyses revealed that, after bout one, the overstride group perceived most soreness and the understride group retained most strength. After the second bout, the overstride and preferred stride frequency groups perceived less soreness than the preferred stride frequency group in bout one. Strength retention was greater after bout two for all groups. In conclusion, strength retention after a repeated bout appears to be independent of the damage experienced in the initial bout of downhill running. However, understriding may provide least protection against soreness in a subsequent bout.

The repeated bout effect refers to the protective effect provided by a single bout of eccentric exercise against muscle damage from a similar subsequent bout. The aim of this study was to determine if the repeated bout was associated with an increase in motor unit activation relative to force production, an increased recruitment of slow-twitch motor units or increased motor unit synchronization. Surface electromyographic (EMG) signals were recorded from the hamstring muscles during two bouts of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions separated by 2 weeks. The EMG per unit torque and median frequency were analysed. The initial bout of eccentric exercise resulted in strength loss, pain and muscle tenderness, while the repeated eccentric bout resulted in a slight increase in strength, no pain and no muscle tenderness (bout x time effects, P < 0.05). Strength, pain and tenderness were unaffected by either bout of concentric exercise. The EMG per unit torque and median frequency were not different between the initial and repeated bouts of eccentric exercise. The EMG per unit torque and median frequency increased during both bouts of eccentric exercise (P < 0.01) but did not change during either concentric bout. In conclusion, there was no evidence that the repeated bout effect was due to a neural adaptation.

Research into the physiology of exercise and kinanthropometry is intended to improve our understanding of how the body responds and adapts to exercise. If such studies are to be meaningful, they have to be well designed and analysed. Advances in personal computing have made available statistical analyses that were previously the preserve of elaborate mainframe systems and have increased opportunities for investigation. However, the ease with which analyses can be performed can mask underlying philosophical and epistemological shortcomings. The aim of this review is to examine the use of four techniques that are especially relevant to physiological studies: (1) bivariate correlation and linear and non-linear regression, (2) multiple regression, (3) repeated-measures analysis of variance and (4) multi-level modelling. The importance of adhering to underlying statistical assumptions is emphasized and ways to accommodate violations of these assumptions are identified.

The length-tension relationship of muscle contraction is well documented in adults. However, research on this relationship in children has been limited. The aim of this study was to compare differences in the torque-joint angle relationship of the quadriceps muscle in children and adults. Eight boys aged 8-10 years and eight men aged 20-26 years performed two maximal voluntary isometric contractions at six knee joint angles (20 degrees, 40 degrees, 60 degrees, 80 degrees, 90 degrees, 100 degrees). The mean of the two trials was used as the performance measure. Both groups demonstrated an expected increase in relative torque as the joint angle increased (P< 0.05). The men produced significantly greater relative torque at 20 degrees, 40 degrees and 60 degrees knee flexion (P < 0.05). The percentage of maximal torque at these angles for the men and boys respectively were: 35.2+/-4.3 vs 15.2+/-12%, 63.6+/-9.1 vs 51.8+/-16.8% and 93.6+/-6.5 vs 84.4+/-14.4%. There were no group differences at 80 degrees or 90 degrees. Peak torque was attained at 80 degrees in men, but decreased significantly (P< 0.05) at 90 degrees and 100 degrees. For boys, peak torque was attained at joint angles of 80 degrees and 90 degrees. The reduction in peak torque at 100 degrees was not statistically significant, but the relative torque at this angle was lower in men than in boys (77.9+/-13.7 vs 87.1+/-10.4%; P< 0.05). In conclusion, the relationship between torque and joint angle appears to be affected by age.

The purpose of this study was to assess the effects of changes in stride length on the symptoms of exercise-induced muscle damage (EIMD) during a repeated bout of downhill running in a group of 18 men and women. Muscle tenderness, plasma creatine kinase activity (CK) and maximal voluntary isometric force were measured before and after two downhill runs, with each run separated by 5 weeks. The first downhill run was at the preferred stride frequency (PSF). Participants were then randomly allocated to one of three sex-balanced groups with equal numbers of men and women: overstride (-8% PSF), understride (+8% PSF) and normal stride frequency for the second downhill run. Stride length had no effect (P>0.05) on muscle tenderness, CK or isometric peak force. Increases in muscle tenderness (P

Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.

OBJECTIVES: (a) to assess the validity and reliability of producing and reproducing a given exercise intensity during cycle ergometry using a braille version of Borg's standard 6-20 rating of perceived exertion (RPE) scale, and (b) to determine whether the exercise responses of blind participants, at a given produced RPE, were similar to those reported in recognised guidelines for sighted subjects. METHODS: Ten healthy registered blind volunteer participants (four women, six men; mean (SD) age 23.2 (9.0) years) performed an initial graded exercise cycle test to determine maximal heart rate (HRMAx) and maximal oxygen uptake (VO2MAX). Three trials of three exercise bouts at RPEs 9, 11, and 13 were then performed in random order on three separate days of the same week, with expired air and heart rate measured continuously. Each exercise bout was followed by 10 minutes of rest. The validity of the scale as a means of producing different exercise intensities was assessed using a two factor (RPE x trial) repeated measures analysis of variance. Intertrial reliability was assessed using intraclass correlation coefficients (ICC) and the bias +/-95% limits of agreement (95%LoA) procedure. RESULTS: Participants reported no difficulty in using the braille RPE scale. When asked to produce exercise intensities equating to RPE 9, 11, and 13, they elicited mean %VO2MAX values of 47%, 53%, and 63% respectively. Analysis of variance showed no significant differences in either %HRMAx or %VO2MAX between trials at each of the three RPEs, but there was a significant difference (p

The purpose of this study was to assess whether young children could reliability regulate exercise intensity production after several practice trials, without reference to objective feedback measures. The study used a new 10-point scale (Cart and Load Effort Rating [CALER] Scale), which depicts a child on a bicycle, at various stages of exertion, towing a cart in which the load increases progressively. After warm-up, 20 children, aged 7-10 years, performed an intermittent, effort production protocol at CALER 2, 5, and 8 on a cycle ergometer. This was repeated on three further occasions in the next 4 weeks. An increase in PO across trials (44, 65, and 79 W at CALER 2, 5, and 8, respectively) confirmed that the children understood the scale. A Bland and Altman limits of agreement (LoA) analysis and an intraclass correlation analysis (ICC) between trials (T) indicated that reliability improved with practice. Intertrial comparisons of overall reliability from T1 to T2 and from T3 to T4 ranged from 0.76 to 0.97 and an improvement in the overall bias +/- 95% limits of agreement from -12 +/- 19 W to 0 +/- 10 W. This study is the first to apply more than two repeated effort production trials in young children and provides strong evidence that practice improves the reliability of effort perception in children. The data also provide preliminary evidence for the validity of the CALER Scale in children aged 7-10 years.

We have considered some of the most important factors involved in designing a viable study that will adequately address the research question. Although we do not profess to be experts in all aspects of the above, we have learned through experience that attention to many of the above points will help to avoid frustration during the experimental process and when the study is presented for external review and subsequent presentation and publication. Good luck in your research.

BACKGROUND: the relationship between activity levels and body fat in children is unclear, despite a large number of studies. The issue is clouded by the wide variety of methods used to assess children's activity levels. It is important to assess whether the type of activity measure influences the fatness-activity relationship. This is a first step to uncovering the role of modifying variables such as gender, age, maturity, etc. PRIMARY OBJECTIVE: This study uses meta-analytic procedures to synthesize the results of such studies and to assess whether the type of activity measure used has an effect on the strength of the relationship observed. METHODS AND PROCEDURES: Fifty studies were located that satisfied the inclusion criteria. Seventy-eight per cent of the studies showed a negative relationship, 18% no relationship and 4% a positive relationship between physical activity and body fatness. Data were analysed using the meta-analytic procedures described by Rosenthal (Meta-analytic Procedures for Social Research, Sage, 1991). MAIN OUTCOMES AND RESULTS: the mean effect size indicated a small to moderate, inverse relationship (r = -0.16). Mean effect sizes differed significantly (F(3,52) = 8.04, p < 0.001) according to the activity measure used: questionnaire, r = -0.14; motion counters, r = -0.18; observation, r = -0.39; heart rate (HR), r = 0.00. Observation measures elicited a significantly stronger relationship with body fat than did questionnaire or heart rate measures (p < 0.05). However, there was no significant difference between the effect sizes elicited by observation and motion counters. Correlational analyses revealed no effect of age group or gender on the strength of the relationship between fatness and activity. CONCLUSIONS: This meta-analysis suggests there is a small to moderate relationship between body fat and activity in children. It is important to note, however, that the size of the relationship depends on the activity measure used. It is therefore recommended that direct measures of movement, such as observation or motion counter methods, are used to assess the relationship of activity levels with health.

Cryotherapy is an effective treatment for acute sports injury to soft tissue, although the effect of cryotherapy on exercise-induced muscle damage is unclear. The aim of this study was to assess the effects of cold water immersion on the symptoms of exercise-induced muscle damage following strenuous eccentric exercise. After performing a bout of damage-inducing eccentric exercise (eight sets of five maximal reciprocal contractions at 0.58 rad x s(-1)) of the elbow flexors on an isokinetic dynamometer, 15 females aged 22.0+/-2.0 years (mean +/- s) were allocated to a control group (no treatment, n = 7) or a cryotherapy group (n = 8). Subjects in the cryotherapy group immersed their exercised arm in cold water (15 degrees C) for 15 min immediately after eccentric exercise and then every 12 h for 15 min for a total of seven sessions. Muscle tenderness, plasma creatine kinase activity, relaxed elbow angle, isometric strength and swelling (upper arm circumference) were measured immediately before and for 3 days after eccentric exercise. Analysis of variance revealed significant (P < 0.05) main effects for time for all variables, with increases in muscle tenderness, creatine kinase activity and upper arm circumference, and decreases in isometric strength and relaxed elbow angle. There were significant interactions (P

Unfamiliar, predominantly eccentric exercise, frequently results in muscle damage. A repeated bout of similar eccentric exercise results in less damage and is referred to as the 'repeated bout effect'. Despite numerous studies that have clearly demonstrated the repeated bout effect, there is little consensus as to the actual mechanism. In general, the adaptation has been attributed to neural, connective tissue or cellular adaptations. Other possible mechanisms include, adaptation in excitation-contraction coupling or adaptation in the inflammatory response. The 'neural theory' predicts that the initial damage is a result of high stress on a relatively small number of active fast-twitch fibres. For the repeated bout, an increase in motor unit activation and/or a shift to slow-twitch fibre activation distributes the contractile stress over a larger number of active fibres. Although eccentric training results in marked increases in motor unit activation, specific adaptations to a single bout of eccentric exercise have not been examined. The 'connective tissue theory' predicts that muscle damage occurs when the noncontractile connective tissue elements are disrupted and myofibrillar integrity is lost. Indirect evidence suggests that remodelling of the intermediate filaments and/or increased intramuscular connective tissue are responsible for the repeated bout effect. The 'cellular theory' predicts that muscle damage is the result of irreversible sarcomere strain during eccentric contractions. Sarcomere lengths are thought to be highly non-uniform during eccentric contractions, with some sarcomeres stretched beyond myofilament overlap. Loss of contractile integrity results in sarcomere strain and is seen as the initial stage of damage. Some data suggest that an increase in the number of sarcomeres connected in series, following an initial bout, reduces sarcomere strain during a repeated bout and limits the subsequent damage. It is unlikely that one theory can explain all of the various observations of the repeated bout effect found in the literature. That the phenomenon occurs in electrically stimulated contractions in an animal model precludes an exclusive neural adaptation. Connective tissue and cellular adaptations are unlikely explanations when the repeated bout effect is demonstrated prior to full recovery, and when the fact that the initial bout does not have to cause appreciable damage in order to provide a protective effect is considered. It is possible that the repeated bout effect occurs through the interaction of various neural, connective tissue and cellular factors that are dependent on the particulars of the eccentric exercise bout and the specific muscle groups involved.

The relationships between children's activity, aerobic fitness, and fatness are unclear. Indirect estimates of activity, e.g. heart rate (HR) and recall, may mask any associations. The purpose of this study was to assess these relationships by using the Tritrac-R3D, a pedometer, and heart rate. Thirty-four children, ages 8-10 yr, participated in the study. The Tritrac and pedometer were worn for up to 6 days. HR was measured for 1 day. Activity measured by Tritrac or pedometer correlated positively to fitness in the whole group (Tritrac, r = 0.66; pedometer, r = 0.59; P < 0.01) and in boys and girls separately (P < 0.05) and correlated negatively to fatness in the whole group (r = -0.42, P < 0.05). In contrast, HR did not correlate significantly to fitness, and HR of >139 beats/min correlated positively to fatness in girls (r = 0.64, P < 0.05). This suggests that HR is misleading as a measure of activity. This study supports a positive relationship between activity and fitness and suggests a negative relationship between fatness and activity.

OBJECTIVE: to assess the test-retest reliability (repeatability) of Borg's 6-20 rating of perceived exertion (RPE) scale using a more appropriate statistical technique than has been employed in previous investigations. The RPE scale is used widely in exercise science and sports medicine to monitor and/or prescribe levels of exercise intensity. The "95% limits of agreement" technique has recently been advocated as a better means of assessing within-subject (trial to trial) agreement than traditional indicators such as Pearson and intraclass correlation coefficients. METHODS: Sixteen male athletes (mean (SD) age 23.6 (5.1) years) completed two identical multistage (incremental) treadmill running protocols over a period of two to five days. RPEs were requested and recorded during the final 15 seconds of each three minute stage. All subjects successfully completed at least four stages in each trial, allowing the reliability of RPE responses to be examined at each stage. RESULTS: the 95% limits of agreement (bias +/- 1.96 x SDdiff) were found to widen as exercise intensity increased: 0.88 (2.02) RPE units (stage 1), 0.25 (2.53) RPE units (stage 2), -0.13 (2.86) RPE units (stage 3), and -0.13 (2.94) RPE units (stage 4). Pearson correlations (0.81, 0.72, 0.65, and 0.60) and intraclass correlations (0.82, 0.80, 0.77, and 0.75) decreased as exercise intensity increased. CONCLUSIONS: These findings question the test-retest reliability of the RPE scale when used to monitor subjective estimates of exercise intensity in progressive (or graded) exercise tests.

We examined whether passive stiffness of an eccentrically exercising muscle group affects the subsequent symptoms of muscle damage. Passive hamstring muscle stiffness was measured during an instrumented straight-leg-raise stretch in 20 subjects (11 men and 9 women) who were subsequently classified as "stiff" (N = 7), "normal" (N = 6), or "compliant" (N = 7). Passive stiffness was 78% higher in the stiff subjects (36.2 +/- 3.3 N.m.rad(-1)) compared with the compliant subjects (20.3 +/- 1.8 N.m.rad(-1)). Subjects then performed six sets of 10 isokinetic (2.6 rad.s(-1)) submaximal (60% maximal voluntary contraction) eccentric actions of the hamstring muscle group. Symptoms of muscle damage were documented by changes in isometric hamstring muscle strength, pain, muscle tenderness, and creatine kinase activity on the following 3 days. Strength loss, pain, muscle tenderness, and creatine kinase activity were significantly greater in the stiff compared with the compliant subjects on the days after eccentric exercise. Greater symptoms of muscle damage in subjects with stiffer hamstring muscles are consistent with the sarcomere strain theory of muscle damage. The present study provides experimental evidence of an association between flexibility and muscle injury. Muscle stiffness and its clinical correlate, static flexibility, are risk factors for more severe symptoms of muscle damage after eccentric exercise.

This study compared the accuracy of heart rate monitoring, pedometry, and uniaxial and triaxial accelerometry for estimating oxygen consumption during a range of activities in Hong Kong Chinese boys. Twenty-one boys, aged 8-10 years, walked and ran on a treadmill, played catch, played hopscotch, and sat and crayoned. Heart rate, uniaxial and triaxial accelerometry counts, pedometry counts, and scaled oxygen uptake (SVO2) were measured. All measures correlated significantly with VO2 scaled to body mass(-0.75) (SVO2). The best predictor of SVO2 was triaxial accelerometry (R-2 = 0.89). Correlations in this study were comparable with those in a previous study that used identical methods on 30 UK boys and girls. These results provide further confirmation that triaxial accelerometry provides the best assessment of energy expenditure and that pedometry offers potential for large population studies.

Delayed-onset muscle soreness (DOMS) is a common sensation following unaccustomed exercise, and especially eccentric exercise. The term DOMS is used to denote not only muscle soreness, but also stiffness, tenderness and pain on active movement. An inherent loss of force-generating capacity and reductions in range of motion are typical functional consequences that accompany DOMS. The symptoms of DOMS are commonly believed to be caused by damage to the muscle; yet DOMS and muscle damage share a poor temporal relationship. This review focuses on empirical research relating to the phenomenon of DOMS, potential underlying mechanisms, functional consequences, and also preventative and treatment strategies.

This consensus statement was prepared by an Ad Hoc Committee on Sports and Children of the International Federation of Sports Medicine (FIMS) and WHO during a symposium on sports and children held in Hong Kong on 11-12 January 1997 and was reviewed by members of the WHO/Cardiovascular Disease Expert Advisory Panel and Members of the WHO Committee on Physical Activity Sport, and Health.

Heart rate telemetry is frequently used to estimate daily activity in children and to validate other methods. This study compared the accuracy of heart rate monitoring, pedometry, triaxial accelerometry, and uniaxial accelerometry for estimating oxygen consumption during typical children's activities. Thirty Welsh children (mean age 9.2 +/- 0.8 yr) walked (4 and 6 km/h) and ran (8 and 10 km/h) on a treadmill, played catch, played hopscotch, and sat and crayoned. Heart rate, body accelerations in three axes, pedometry counts, and oxygen uptake were measured continuously during each 4-min activity. Oxygen uptake was expressed as a ratio of body mass raised to the power of 0.75 [scaled oxygen uptake (sVO2)]. All measures correlated significantly (P < 0.001) with sVO2. A multiple-regression equation that included triaxial accelerometry counts and heart rate predicted sVO2 better than any measure alone (R2 = 0.85, standard error of the estimate = 9.7 ml.kg-0.75.min-1). The best of the single measures was triaxial accelerometry (R2 = 0.83, standard error of the estimate = 10.3 ml.kg-0.75.min-1). It is concluded that a triaxial accelerometer provides the best assessment of activity. Pedometry offers potential for large population studies.

Studies addressing children's perceptions of exercise effort have appeared steadily in the scientific literature over the last 20 years, though they have been relatively sparse in number. With little or no regard for their suitability, researchers initially applied to children the methods and applications of the rating of perceived exertion (RPE) notion established amongst adults. Whilst some success was claimed, findings were inconclusive, possibly because of the use of an inappropriate measurement scale. More recently, the development of the child-specific Children's Effort Rating Table (CERT) has advanced research in this domain and helped to focus attention on the numerous problems of applying this psychophysical concept to such immature subjects. Accordingly, the scope for further research in this discipline is now far broader than ever before.

Understanding the progression of physical activity behaviour from childhood to adulthood requires a valid, reliable and practical method of assessing activity levels which is appropriate for use in large groups. The measurement of physical activity in large scale research projects requires a method which is low in cost, agreeable to the study volunteer and accurate. Self-report can be used to determine adult activity patterns, but children lack the cognitive ability to recall details about their activity patterns. Heart rate telemetry has been used to estimate daily activity in children as a sole criterion and to validate commercial accelerometers. However, heart rate is an indirect estimate of physical activity which makes assumptions based on the linear relationship between heart rate and oxygen uptake. It is sensitive to emotional stress and body position, and takes longer to reach resting levels after physical exertion compared with oxygen uptake. It also lags behind movement, particularly as children's physical activity is spasmodic or intermittent in nature. One alternative is the pedometer. Many early studies reported that the pedometer is inaccurate and unreliable in measuring distance or counting steps. While reasonably accurate at mid range speeds, the accuracy of the pedometer decreases in very slow walking or very fast walking or running. However, more recent studies have examined the efficacy of using pedometers to assess daily or weekly activity patterns as a whole, and these have produced more promising results. In this regard, the pedometer has a number of advantages. It is very cheap, objective and does not interfere with daily activities and is therefore appropriate for use in population studies. Commercial accelerometers with a time-sampling mechanism offer further potential and could be used to provide a picture of the pattern of children's activity. As it has been observed that prolonged activity periods are not typically associated with childhood behaviour patterns, the use of a threshold value for 'aerobic' training stimulus is not appropriate as a cut-off value for physical activity. Instead, there is evidence to suggest that the total activity data measured by pedometers over limited periods of time may be more appropriate to assess how active children are.

Downhill running, particularly for the untrained subject, is a mode of eccentric exercise that produces delayed-onset muscle soreness (DOMS) in the quadriceps femoris muscle which is maximal between 24 and 72 h after the exercise. It is not clear whether sensitivity to pain is uniform over the surface of the muscle, or whether some locations become more sensitive following eccentric exercise. The purpose of this investigation was to compare pressure pain tolerance (PPTO) at various sites on the quadriceps femoris muscle on 2 days prior to exercise, immediately after, and at 24, 48 and 72 h following a bout of eccentric exercise. Fifteen untrained female subjects performed a 40 min downhill run on a motorized treadmill with a gradient of -12%, where running speed was adjusted to elicit a heart rate of approximately 60% of age-related maximum heart rate reserve, and were measured for PPTO at seven sites on the right thigh. Sites were visited sequentially three times and repeated on each of 6 days. Pressure pain tolerance as an index of tenderness was determined using a strain gauge algometer. Two sites were close to the distal myotendinous junction, three sites were located on the mid belly of the muscle and two sites were located at the proximal myotendinous junction. There was a significant difference (p

Sixty 60-day-old Sprague-Dawley male rats were subjected to exhaustive and non-exhaustive exercise treatment over a period of 3, 5 and 7 weeks. Moderate exercise consisted of running on the treadmill at 10% grade at 10 m/min for 20 min for 5 days per week, while exhaustive running consisted of running at 10% grade at 15 m/min with an increase of 5 m/min every 5 min for 5 days per week. Half of the exercised rats were subjected to immersion in 4 degrees C water for 5 min after each exercise bout. Histological analyses of the gastrocnemius showed that ultrastructural damage of myofibrils occurred after 5 weeks of exhaustive running and 7 weeks of moderate running. With post-exercise immersion in 4 degrees C water for 5 min, the occurrence of ultrastructural damage advanced by 2 weeks in both treatments. It was concluded that the application of cryotherapy to the exercise groups was deleterious. Muscle damage occurred earlier in the treatment group and the degree of damage was also more serious over the same time period. This study supports the recommendation that the use of cryotherapy to reduce pain and haematoma formation should be coupled with rest for at least 48 hours.

OBJECTIVE: the purpose of this study was to assess the efficacy of Borg's rating of perceived exertion (RPE) scale to predict maximal exercise levels to control exercise intensity in patients taking atenolol for the treatment of essential hypertension. Normally, a standard formula (220-age) is used for calculating a percentage of exercise intensity, but beta blockade can cause reductions in maximal heart rate of between 20 and 30%. METHODS: Patients were split into a control group-10 men and 10 women, aged 50 (SD 12) and 46 (9) respectively, who had risk factors for cardiovascular disease but were not taking any drugs, and a treatment group-11 men and 11 women, aged 53 (13) and 55 (13) respectively, who were established on 25-100 mg of atenolol. All patients performed two submaximal tests on a cycle ergometer. Test 1 was an estimation test, during which the RPE was reported for each increment in work rate. Test 2 was an RPE production test, during which the patient regulated the work rate according to his/her perception of effort at four predetermined points on the RPE scale (RPE 9, 13, 15, 17). RESULTS: in both tests the individual correlations (r) between RPE, heart rate, and work rate ranged from 0.96 to 0.99. Analysis of variance showed no significant difference in maximal heart rate and maximal power output for the control group when predicted from the regression lines of RPE versus heart rate and RPE versus power output in the estimation test. However, the prediction of maximal power output was lower in the women in the control group and patients in the treatment group when this was predicted from the effort production protocol (P < 0.01). When exercise intensity at each RPE was expressed relative to maximal power output there were no differences between treatment and control groups. CONCLUSION: the findings from this study confirmed the strong positive relation between RPE, heart rate, and work rate in these patients in both passive effort estimation and active effort production protocols. However, caution in applying these procedures is required because the prediction of maximal exercise levels may be lower when effort production procedures are used.

This paper describes the reliability of a new procedure of applying force to a muscle site using a computer-mediated myometric procedure to measure a discomfort-pain threshold. 24 female subjects were divided into four groups. Each group was tested on three occasions (trial) at four muscle sites (site) repeated daily over four days (day). Each group received one of four different rates of force application (ramp). Analysis of variance (ramp by day by site by trial) showed a significant main effect for trials and discomfort-pain threshold at different muscle sites, but no significant main effect for days or ramps. Intraclass correlations for each muscle site were in the range of R = 0.73 to 0.98. This procedure appears to be a valid, reliable and nonintrusive means of assessing the muscle discomfort-pain threshold.

Unaccustomed exercise (usually of an eccentric nature) is often followed by delayed onset muscle soreness (DOMS). Previous studies have found that prior eccentric activity produces a training effect which reduces DOMS and morphological changes. The aim of this study was to examine the effects of a prior bout of maximal isokinetic eccentric exercise on DOMS, strength loss and plasma creatine kinase (CK) changes following a downhill run. Ten male subjects with a mean (+/- S.D.) age of 22.5 +/- 2.8 years, body mass of 62.67 +/- 0.05 kg and height of 176 +/- 3 cm were allocated to either a treatment group or a control group. The treatment group performed 100 maximal eccentric activations of the knee extensors in the dominant leg at 0.52 rad s-1. Two weeks later, the downhill run was performed on a motor-driven treadmill. This consisted of five bouts of 8 min at a gradient of -10% at a speed corresponding to 80% of the predicted maximal heart rate. The untrained group performed the downhill run as above but without the prior isokinetic session. Tenderness measurements, plasma CK activity and concentric and eccentric isokinetic peak torque measurements of the knee extensors at 0.52 and 2.83 rad s-1 were recorded prior to, immediately following and 2, 4 and 7 days after each protocol. The isokinetic protocol caused an increase (P < 0.01) in CK and tenderness and a decrease (P < 0.05) in concentric and eccentric torque at both speeds in the treatment group. Following the downhill run, a reduction in peak torque (P < 0.01) was observed in the eccentric and concentric modes at both isokinetic speeds in the control group. For the treatment group, the decrease in peak torque occurred only at the faster eccentric speed. With the exception of the faster eccentric speed, the decrement in peak torque was greater in the control group in all post-exercise isokinetic strength tests. There was less tenderness (P < 0.01) in the trained knee extensor muscle group. Peak torque also returned to pre-downhill values earlier for the trained group. Although plasma CK activity increased in both groups after downhill running, it was much lower (P < 0.01) in the trained group. The results suggest that a prior bout of isokinetic eccentric training reduces muscle damage, reduces the amount of strength loss and decreases the sensation of DOMS after downhill running.

The purpose of this study was to examine psychological affect at different ratings of perceived exertion (RPE) in 15 high- and 15 low-active women. Both groups performed three steady-state exercise bouts on a cycle ergometer at RPEs 9, 13, and 17 and reported their affect in the last 20 sec. of and 5 min. after each work rate. There were no differences between groups in percentage of maximal oxygen uptake (% VO2max) at each RPE. Low-active women reported feeling significantly more negative at RPE 17 than RPE 9 and less positive than the high-active women at RPEs 9, 13, and 17. In addition, all subjects reported more positive feelings 5 min. postexercise than in the last 20 sec. of exercising, especially at RPE 17. These results have implications for exercise prescription in groups differing in habitual activity levels.

The ratings of perceived exertion (RPE) scale has received widespread acceptance for gaining a subjective estimate of work intensity and as a means of monitoring and regulating exercise intensity across a variety of populations. The original premise for the use of the scale was its high correlation with heart rate (HR). Although individual correlations between HR and RPE in individuals on beta-blocker therapy are probably as high as in untreated individuals, there is evidence to suggest that the RPE response is mediated at a given work rate, particularly at higher absolute work rates. The variation in the RPE response appears to be mediated by the type of beta-blocker therapy administered. In the interests of safety it is necessary for the exercise specialist to develop at least a basic understanding of the mechanism and effects of beta-blocker therapy as they relate to exercise prescription. beta-Blocking drugs cause a decrease in HR and cardiac output at rest and during exercise, a decrease in myocardial contractility and a decrease in coronary and muscle blood flow. These effects can initiate premature fatigue and apprehension in the exercising patient. In the light of these responses, the RPE scale provides important information and may be used to increase the accuracy of monitoring and the prescription of exercise intensity in the cardiac population. While results regarding the use and accuracy of the scale during beta-blocker treatment are equivocal, this appears to be due mainly to variations in dosage of the drug, the mode, intensity and duration of exercise and the health status of the individuals used. Overall, the RPE scale appears to be an appropriate monitoring tool, particularly when it is used after a learning period. It is concluded that nonselective beta-blockade therapy increases RPE, particularly localised RPE. This could be attributed to a decreased blood flow and oxygen delivery to the muscle and altered glycolytic metabolism, which increases local muscle fatigue. There is no evidence to suggest a decrease in the total level of oxygen consumption at given work rates. However, as beta-blocker therapy reduces the maximal oxygen consumption (VO2max) attainable, this serves to increase the exercise intensity at all work rates. Thus, for a given absolute work rate, the RPE response is higher. However, when the work rate is expressed as a proportion of the VO2max attainable during beta-blockade, the differences in RPE are minimised or disappear. Although the evidence is not conclusive, it appears that cardioselective beta-blocker therapy does not have such profound effects on the RPE response, compared with nonselective beta-blocker therapy, when this is expressed as a proportion of VO2max. However, localised RPE tends to be higher for nonselective beta-blocker therapy. Thus, the evidence indicates that RPE can be used to estimate exercise intensity, provided the specific effects of the type of beta-blocker therapy on local and central fatigue (and local and central RPE) are taken into account. Studies which have examined the effects of an endurance training programme during beta-blocker therapy have shown that RPE are decreased at given work rates after training. This has been observed for cardioselective and nonselective beta-blocker therapy, and local and central RPE. There is also some evidence to suggest that the RPE can be used as the controlling variable to regulate the exercise response. Patients on cardioselective beta-blocker therapy produce similar exercise intensities to other cardiac patients who are not receiving beta-blocker treatment.

The purpose of this study was to examine differences in the rating of perceived exertion (RPE) and affect, as assessed by a bipolar feeling scale (FS) during cycle ergometry in a steady-state and a nonsteady-state condition in active and inactive individuals. 71 subjects completed a self-report questionnaire on physical activity and were assigned to two groups, a low-active group of 16 men and 18 women and a high-active group of 18 men and 19 women. On Day 1 all subjects completed a sub-maximal exercise test to predict maximum oxygen uptake (VO2max) from which work rates corresponding to 60% and 90% VO2max were calculated. On Day 2 half of the subjects completed a work rate equivalent to 60% VO2max whilst the other half completed a 90% VO2max work rate. On Day 3 alternative work rates were completed. RPE and FS were recorded after 2 and 4 min, at each work rate on both days. Mixed-model, 4-factor (gender x group x work rate x time) analyses of variance with repeated measures on work rate and time were conducted on the FS and RPE data. RPE was higher after 4 min, at both intensities, and there was a greater increase in RPE between 2 and 4 min, at the 90% than the 60% work rate. Rated feeling was more positive at the 60% work rate, high-active subjects were more positive than low-active subjects and rated feeling was lower in Minute 4 for both groups. The following interactions were observed: rated feeling was more negative after 4 min. for the low-active group compared to the high-active group at 2 and 4 min. and the low-active group reported more negative feeling at the 90% work rate compared to the 60% work rate while the high-active group did not change significantly. Timing of the RPE is important if used to prescribe exercise intensity. Further, low-active subjects should be encouraged to exercise at moderate intensities and discouraged from focusing on how they feel immediately before they finish a session.

An eccentric muscle activation is the controlled lengthening of the muscle under tension. Functionally, most leg muscles work eccentrically for some part of a normal gait cycle, to support the weight of the body against gravity and to absorb shock. During downhill running the role of eccentric work of the 'anti-gravity' muscles--knee extensors, muscles of the anterior and posterior tibial compartments and hip extensors--is accentuated. The purpose of this paper is to review the relationship between eccentric muscle activation and muscle damage, particularly as it relates to running, and specifically, downhill running.

There is little information on the application of generalized prediction equations to ethnic groups other than Europeans and groups of European descent. The purpose of this study was to crossvalidate conventional equations on a group of 56 Chinese adults. Body density was assessed by underwater weighing and also predicted by equations which use a combination of selected skinfolds-biceps, triceps, pectoral, subscapular, abdominal, suprailiac, thigh and calf. There were significant correlations (P < 0.01) between the various methods of predicting percentage fat. However, analysis of variance revealed significant differences (P < 0.01) between mean values. In the men, the Jackson and Pollock equation underestimated, and the Durnin and Womersley equation overestimated, the percentage fat predicted by underwater weighing. The best predictor site in this group was the medial calf skinfold (r = 0.81), which is not included in either equation. In the women, the best predictor sites were the triceps, suprailiac and thigh. As these sites are also used in the Jackson et al. equation, it is not surprising that there was no difference between the prediction of percentage fat by this equation and underwent weight. It is concluded that the Durnin and Womersley and Jackson and Pollock equations tend to overestimate and underestimate, respectively, the percentage fat in Chinese men. Alternative equations which use the calf skinfold may be more appropriate for this ethnic group. In Chinese women, there appears to be good agreement between Jackson and Pollock and hydrodensitometric estimations of percentage fat.

This paper describes the rationale for the Children's Effort Rating Table (CERT) designed for assessing perceived exertion by children aged 6 to 9 years. This device is similar to Borg's Rating of Perceived Exertion (RPE) which is internationally recognized and currently used in conjunction with standard metabolic measures in a wide range of settings where exercise is prescribed and the intensity of various forms of physical activity is regulated by adults. We devised CERT for use in our research on the development of perception of effort by younger children. Some validation research on CERT has been completed.

It has been shown that ultrasonographic measurements can be used to predict body composition in adults. The purpose of this study was to assess the relationship between ultrasonograph and caliper (SKF) measurements of subcutaneous adipose tissue thickness in athletic Caucasian (English, E) and Asian (Chinese, C) men against estimates of body composition determined from hydrodensitometry (HYD). The usefulness of a proposed ultrasonographic method of estimating lean and fat proportions in the upper and lower limbs was also evaluated as a potential method of predicting body composition. Ultrasonography (US) was used to measure adipose and skin thickness at the following sites: biceps, triceps, subscapular, suprailiac, abdominal, pectoral, thigh and calf. Caliper measurements were also made at the above sites. Subcutaneous fat thickness and segmental radius were measured directly from the display screen of the ultrasonic scanner (Aloka 500 SD). By applying the geometry of a cone, the proximal and distal radii of the upper arm and upper leg were used to calculate the proportionate volumes of adipose tissue. The best correlations for US and SKF were obtained at the quadriceps, subscapular and pectoral sites for E (r = 0.96, 0.93 and 0.90, respectively) and at the quadriceps, calf and abdominal sites for C (r = 0.90, 0.81 and 0.75, respectively). The best ultrasonographic predictor of the percentage fat in both groups was the percentage adipose tissue volume in the upper leg (r = 0.83 and 0.79 for C and E, respectively). Stepwise multiple regression analysis indicated that the prediction of percentage fat was improved by the addition of the ultrasonographic abdomen measurement in both groups: Chinese sample: %fat = %fat(leg) (0.491) + US abdomen (0.337) + 0.95 ( R = 0.89, s.e.e. = 1.9%); English sample: %fat = %fat(leg) (0.435) + US abdomen (0.230) - 0.765 ( R = 0.80, s.e.e. = 3.6%). It is concluded that ultrasonographic measurements of subcutaneous adipose tissue and volumetric assessment of percentage adipose tissue in the thigh are useful estimates of body composition in athletic English and Chinese males.

The purpose of this study was to examine the validity of a recently developed rating scale of perceived exertion, the Children's Effort Rating Table (CERT), for controlling exercise intensity in young children. 16 children (M age = 9.9 yr. SD = 1.2) performed three separate exercise tests on a mechanically braked cycle ergometer. Stage I (response protocol) consisted of a graded test with heart rate and perceived effort rating recorded in response to specified steady-state work outputs. Stage II (production protocol) examined subjects' ability to produce work outputs corresponding to levels 5, 7, and 9 of the CERT. This protocol was repeated on a further occasion (Stage III) to assess the reliability of the findings. Pearson correlations between ratings and heart rate (0.76) and ratings and work output (0.75) highlight the potential of the scale as a valid measure of exercise intensity. Also, the work rates produced by subjects in Stage II correlated 0.89 with those predicted from Stage I; however, analysis of variance showed that work output was significantly lower in Stage II than predicted. Finally, an intraclass correlation of 0.91 between Stages II and III suggests that the scale gave a reliable estimate of exercise intensity of children. The findings from this pilot study suggest that children's perceptions of effort might be used to guide intensity of exercise during structured activity classes.

There is limited information on the accuracy of bioelectrical impedance analysis (BIA) for estimating body composition in children. The purpose of this study was to evaluate BIA measurements for estimating fat mass and fat-free mass in 94 Chinese boys and girls aged 11-17 years. Percent fat (%fatskf) and fat-free mass (FFMskf) were predicted by regression of skinfolds in an equation which is founded on a multicomponent model of body composition in children. Multiple-regression analyses were applied to the data to determine if height2 divided by resistance (resistance index) (RI) could accurately predict FFMskf and %fat. Correlations (R) and predictive accuracy (standard error of the estimate, S.E.E.) for FFMskf for RI alone were 0.94 and 2.7 kg; for RI and body mass this improved to 0.96 and 2.2 kg, and for estimation of %fatskf from RI and body mass these values were 0.78 and 4.7%, respectively. A previously published prediction equation, developed on Caucasian children and which also used RI and body mass, was also cross-validated with the Chinese sample in this study. There was no difference between the predicted values from this equation and FFM and %fat predicted by the skinfold technique. The correlation coefficient for FFM was 0.96 and the S.E.E. was similar to that originally reported for the Caucasian sample. We conclude that BIA is a reliable and acceptably accurate method of estimating anthropometrically determined body composition in Chinese youth.

The assessment of frame size is a problematic and ambiguous area. The purpose of this study was to assess the level of agreement between various techniques of assessing frame size in a group of 27 healthy and active men aged 18-24 years, and also to assess which anthropometric variables were best associated with a measure of actual frame size (AFS) which is proposed in this study. Actual frame size was measured by the summation of a series of bone breadths, lengths and depths on a sub-sample of 17 men. The results of the study revealed substantial discordance between methods of assessing frame size. The variables which correlated most highly with AFS (P < 0.01) were body mass, ankle breadth, hand length and chest breadth, respectively. These variables were also positively correlated (P < 0.01) with fat-free mass (FFM), with no significant correlation with fat mass in either case. of the various documented methods used to assess frame size, the 'HAT' technique, which incorporates biacromial and bitrochanteric breadths, was more highly correlated with AFS than both elbow breadth (currently used in height-weight insurance tables) and the height/wrist circumference index. The latter measure was not highly correlated with AFS, body mass and FFM in this study. It was concluded that ankle breadth and hand length may be better predictors of frame size in young men than other bone dimensions. In addition, the results of this preliminary investigation have substantiated the potential viability of an AFS model. Future research using this technique is recommended to determine true indicators of frame size in a larger and more heterogeneous population.

The purpose of this study was to examine body fat estimation using three methods of electrical impedance (the BIA-103 Body Composition Analyser--RJL Systems, Detroit; the BMR 2000 Body Composition Analyzer--Berkeley Medical Research, San Leandro; the BC300 Body Composition Analyzer--Spacelabs, Dallas) and an infra-red interactance method (Futrex 5000 Analyzer--Futrex Inc. Gaithersburg) as an alternative to hydrodensitometry. Five different groups were examined using at least one of the electrical systems and in all cases utilising hydrodensitometry as the criterion method. The results produced highly significant correlations between all methods, but caution is recommended due to the limited common variance in some cases. The individual electrical methods differed from hydrodensitometry by a maximum of 1.1% in obese women, by 21.6% in athletic adults, by 6.2% in the slightly obese group, by 8.1% in normal women and by 56.0% in normal children. Significant mean differences between one of the impedance methods and hydrodensitometry were only noted in two of the groups tested. This suggests, allowing for the limitations of hydrodensitometry itself, that the other three electrical methods appear to be reasonably valid alternatives to underwater weighing, especially for field work of an epidemiological nature.

This review describes the phenomenon of delayed onset muscle soreness (DOMS), concentrating upon the types of muscle contraction most likely to produce DOMS and the theories underlying the physiological mechanisms of DOMS. Ways of attempting to reduce the effects of DOMS are also summarized, including the application of physical and pharmacological therapies to reduce the effects of DOMS and training for reduction or prevention of DOMS.

The effect of very low calorie diet (VLCD) on fat-free mass (FFM) and physiological response to exercise is a topic of current interest. Ten moderately obese women (aged 23-57 years) received VLCD (1695 kJ.day-1) for 6 weeks. FFM, estimated by four conventional techniques, and heart rate (fc), blood lactate (la(b)), mean arterial pressure (MAP), respiratory exchange ratio (R) and rating of perceived exertion (RPE) were measured during a submaximal cycle ergometry test 1 week before, in the 2nd and 6th week, and 1 week after VLCD treatment. Strength and muscular endurance of the quadriceps and hamstrings were tested by isokinetic dynamometry. The 11.5-kg reduction in body mass was approximately 63% fat and 37% FFM. The latter was attributed largely to the loss of water associated with glycogen. Whilst exercise fc increased by 9-14 beats.min-1 (P < 0.01), there were substantial decreases (P < 0.01) in submaximal MAP (1.07-1.73 kPa), la(b) (0.75-1.00 mmol.l-1 and R (0.07-0.09) during VLCD. R and fc returned to normal levels after VLCD. Gross strength decreased (P < 0.01) by 9 and 13% at 1.05 rad.s-1 and 3.14 rad.s-1, respectively. Strength expressed relative to body mass (Nm.kg-1) increased (P < 0.01) at the lower contraction velocity, but there was no change at the faster velocity. Muscular endurance also decreased (P < 0.01) by 62 and 82% for the hamstrings and quadriceps, respectively. We concluded that the strength decrease was a natural adaptation to the reduction in body mass as the ratio of strength to FFM was maintained.(ABSTRACT TRUNCATED AT 250 WORDS)

High-intensity eccentric contractions induce performance decrements and delayed onset muscle soreness. The purpose of this investigation was to study the magnitude and time course of such decrements and their interrelationships in 26 young women of mean(s.d.) age 21.4(3.3) years. Subjects performed 70 maximal eccentric contractions of the elbow flexors on a pulley system, specially designed for the study. The non-exercised arm acted as the control. Measures of soreness, tenderness, swelling (SW), relaxed elbow joint angle (RANG) and isometric strength (STR) were taken before exercise, immediately after exercise (AE), analysis of variance and at 24-h intervals for 11 days. There were significant (P < 0.01, analysis of variance) changes in all factors. Peak effects were observed between 24 and 96 h AE. With the exception of STR, which remained lower (P < 0.01), all variables returned to baseline levels by day 11. A non-significant correlation between pain and STR indicated that pain was not a major factor in strength loss. Also, although no pain was evident, RANG was decreased immediately AE. There was no relationship between SW, RANG and pain. The prolonged nature of these symptoms indicates that repair to damaged soft tissue is a slow process. Strength loss is considered particularly important as it continues when protective pain and tenderness have disappeared. This has implications for the therapeutic management of patients with myopathologies and those receiving eccentric exercise for rehabilitation.

Fat-free mass was measured by hydrodensitometry, electrical impedance and total body potassium before and after water and electrolyte loss induced by (a) the administration of the diuretic frusemide, and (b) sweat loss. All methods of measuring fat-free mass were shown by pilot experiments to have procedural reliability. The diuretic caused a reduction in apparent fat-free mass of 2.63 kg by the impedance method, of 2.33 kg by hydrodensitometry and of 1.8 kg by total body potassium. Water and electrolyte loss from sweating caused a fat-free loss of 2.3 kg, 2.7 kg and 1.3 kg by the same three procedures. Urinary potassium accounted for about one fifth of the observed 40K fat-free mass loss. Each method was thus clearly sensitive to the induced water loss. These data suggest that in evaluating the composition of weight loss, existing methods of measuring body composition do not distinguish between water and other more critical components of fat-free mass. It is thus essential that stable hydration levels are established for any longitudinal comparison of weight loss by these methods.

The nature and magnitude of the training effect is a function of the frequency, duration and intensity with which vigorous exercise is undertaken. The intensity dimension is a key element in producing changes in central cardiovascular haemodynamics, but because of a 'self-awareness' factor implicated in both the reporting and regulating the intensity level, the determination of this parameter is difficult. Contemporary research with psychophysical ratings of effort sense has led to the recommendation by the American College of Sports Medicine that the rating of perceived exertion is a useful device in the determination of exercise intensity. This paper presents a review of research related to the setting of exercise intensity from a psychophysiological standpoint, and includes a set of observations from research which has examined the influence of perceptual, cognitive and affective variables on the reporting of the rating of perceived exertion.

Body composition was assessed in naturally lean female subjects who never had need to diet. At BMI 21-22 their body weight distribution of 75 per cent FFM and 25 per cent fat was compared with subjects who had dieted below BMI 25 by various conventional self-selected diets; subjects who had dieted to BMI 21-22 by VLCD and subjects who were dieting with VLCD but were still above BMI 25. These body composition studies support values of BMI 22-22 as a better estimate of desirable weight in women than BMI 25. At BMI 21-22 the distribution of body weight between fat and FFM of post VLCD dieters matches that of normal lean women.

This study assessed the reliability of ratings of perceived exertion (RPE) for the prescription of exercise intensity during cycling. Ten healthy men (21 to 62 years) and six women (25 to 50 years) attended the laboratory four times, 5 to 7 days apart. On the first visit each subject's maximal oxygen uptake was measured and, subsequently, they cycled at constant work rates based on their perception of ratings 9, 13 and 17 of the Borg 6-20 scale by regulating the resistance of the ergometer without reference to the instrument display panel. Analysis of variance revealed no significant between-trial differences with regard to oxygen uptake (VO2) or heart rate for men or women. The relative exercise intensities corresponding to the 3 ratings of exertion did not differ between men and women. Between-trial correlations for VO2 were highest for visits two and three at RPE levels 9 and 13 (r = 0.83 and r = 0.94) and consistently high (r = 0.92 or greater) for the three trials at RPE17. These data suggest that RPE is a useful frame of reference for the regulation of high levels of exercise intensity in healthy men and women. Small amounts of practice with the scale improve its applicability at lower exercise levels.

The purpose of this study was to evaluate the use of the rating of perceived exertion (RPE) as a means of regulating the intensity of exercise during running. The subjects were healthy, relatively fit young adults (16 men and 12 women). Estimates of effort were recorded using the Borg 6-20 Scale whilst the maximal oxygen uptake of the subjects was measured as they ran on an electrically driven treadmill. In a further session, the same subjects were requested to run on the treadmill at constant exercise intensity based on their interpretation of levels 9, 13 and 17 of the Borg Scale. They regulated their running speed and the treadmill gradient but had no knowledge of performance from the equipment display panel. A linear regression analysis was carried out to examine the relationship between heart rate, perceived exertion and relative metabolic demand. This revealed that the rating of perceived exertion was at least as good a predictor of exercise intensity as heart rate in both the graded exercise test and effort production test. The results support the view that RPE may be used to predict relative metabolic demand, especially at higher workloads and could be a useful medium for controlling intensity of effort during vigorous exercise in such subjects.

The rating of perceived exertion (RPE) was assessed at power outputs (PO) corresponding to 30%, 60% and 90% of predicted maximal oxygen uptake (VO2 max) on a cycle ergometer in 30 adolescent schoolboys (age range 15-17 years). Analysis of correlations (r) for heart rate (HR):PO (r = 0.74 p less than 0.01) and rating of perceived exertion (RPE): HR (r = 0.74 p less than 0.01) were similar to values drawn from adult samples. It was concluded that there is a close relationship between RPE, HR and relative exercise intensity in adolescent schoolboys.

Arm (A), leg (L) and combined arm and leg (A + L) ergometry modes were compared at power outputs of 49, 73.5 and 98 W. Selected cardiorespiratory variables and a rating of perceived exertion (RPE) were measured for 19 males of mean age 25.7 (+/- 5.5) years. Oxygen uptake (VO2), heart rate (HR), minute ventilation and rating of perceived exertion (RPE) were all higher (p less than 0.01) in a compared with L and a + L. Gross mechanical efficiency was significantly lower in a (p less than 0.01) than in L or a + L. No differences were observed in any measurements between L and a + L. the correlations between RPE and cardiorespiratory variables were higher for a (RPE:VO2, r = 0.87, p less than 0.01; RPE:HR, r = 0.78 p less than 0.01) than for L and a + L.

The purpose of this study was to compare the aerobic fitness of two groups of male college students: 32 Anglo-Saxon males (age range 16-18 years) with 27 Indian males, born in England, (age range 16-23 years), none of whom was highly active in any particular sport. Maximal oxygen uptake was estimated by submaximal test on a cycle ergometer and percent body fat was assessed by skinfold calipers. The Anglo-Saxon group had higher absolute and relative maximal oxygen consumption values and higher body weight. There was no difference in percent fat between the two groups. Strength data were also provided for descriptive purposes.

The study of fluctuations in athletic performance attributable to the menstrual cycle has been an area of considerable interest and controversy for well over half a century. Studies have included simple observations of performance in athletic events, and have also documented specific physical, psychological and physiological changes as they relate to varying hormonal levels of the menstrual cycle. Advantages and disadvantages to human performance have been attributed to various phases of the cycle. Many investigators have documented evidence to suggest that the premenstrual phase is often associated with decreased performance. Others have noted that there are specific physiological changes, inherent in athletic performance, occurring in the follicular and luteal phases of the menstrual cycle. However, it is evident that there is conflict within the literature. This review considers the evidence for the cyclic effects of the regular or normal menstrual cycle on performance. It examines surveyed evidence of the effects of the regular menstrual cycle on athletic performance, effects on psychological and perceptual factors, maximum oxygen uptake, endurance and time to fatigue, temperature, sweating, bodyweight, respiratory drive, blood lactate, carbohydrate and lipid metabolism, and cardiovascular parameters. It is concluded that there is considerable variation in the findings of the literature and that any reported variations in performance may well be greatly influenced by intersubject variability, the nature of the exercise, and the nutritional status of the athlete, as well as minor changes that could be attributable to the menstrual cycle.