Scaling behavior of VO2peak in trained wheelchair athletes

Allometric exponents for scaling running economy in human samples: A systematic review and meta-analysis

Ratio-scaled VO2 is the widely used method for quantifying running economy (RE). However, this method should be criticized due to its theoretical defect and curvilinear relationship indicated by the allometric scaling, although no consensus has been achieved on the generally accepted exponent b value of body weight. Therefore, this study aimed to provide a quantitative synthesis of the reported exponents used to scale VO2 to body weight. Six electronic databases were searched based on related terms. Inclusion criteria involved human cardiopulmonary testing data, derived exponents, and reported precision statistics. The random-effects model was applied to statistically analyze exponent b. Subgroup and meta-regression analyses were conducted to explore the potential factors contributing to variation in b values. The probability of the true exponent being below 1 in future studies was calculated. The estimated b values were all below 1 and aligned with the 3/4 power law, except for the 95 % prediction interval of the estimated fat-free body weight exponent b. A publication bias and a slightly greater I2 and τ statistic were also observed in the fat-free body weight study cohort. The estimated probabilities of the true body weight exponent, full body weight exponent, and fat-free body weight exponent being lower than 1 were 93.8 % (likely), 95.1 % (very likely), and 94.5 % (likely) respectively. 'Sex difference', 'age category', 'sporting background', and 'testing modality' were four potential but critical variables that impacted exponent b. Overall, allometric-scaled RE should be measured by full body weight with exponent b raised to 3/4.

Toward a Standardized and Individualized Laboratory-Based Protocol for Wheelchair-Specific Exercise Capacity Testing in Wheelchair Athletes: A Scoping Review

ABSTRACT

Previous studies on handrim wheelchair-specific (an)aerobic exercise capacity in wheelchair athletes have used a diversity of participants, equipment, and protocols. Therefore, test results are difficult to compare among studies. The first aim of this scoping review is to provide an overview of the populations studied, the equipment and protocols used, and the reported outcomes from all laboratory-based studies on wheelchair-specific exercise capacity in wheelchair athletes. The second aim is to synthesize these findings into a standardized, yet individualized protocol. A scoping literature search resulted in 10 anaerobic and 38 aerobic protocols. A large variety in equipment, protocol design, and reported outcomes was found. Studies that systematically investigated the influence of protocol features are lacking, which makes it difficult to interpret and compare test outcomes among the heterogeneous group of wheelchair athletes. Protocol design was often dependent on a priori participant knowledge. However, specific guidelines for individualization were missing. However, the common protocol features of the different studies were united into guidelines that could be followed when performing standardized and individualized wheelchair-specific exercise capacity tests in wheelchair athletes. Together with guidelines regarding reporting of participant characteristics, used equipment, and outcome measures, we hope to work toward more international agreement in future testing.

Is there really a proportional relationship between VO2max and body weight? A review article

Maximum oxygen uptake (VO_2max) is a “gold standard” in aerobic capacity assessment, playing a vital role in various fields. However, ratio scaling (VO2maxbw), the present method used to express relative VO_2max, should be suspected due to its theoretical deficiencies. Therefore, the aim of the study was to revise the quantitative relationship between VO_2max and body weight (bw). Dimensional analysis was utilized to deduce their theoretical relationship, while linear or nonlinear regression analysis based on four mathematical models (ratio scaling, linear function, simple allometric model and full allometric model) were utilized in statistics analysis to verify the theoretical relationship. Besides, to investigate the effect of ratio scaling on removing body weight, Pearson correlation coefficient was used to analyze the correlation between VO2maxbw and bw. All the relevant data were collected from published references. Dimensional analysis suggested VO_2max be proportional to bw23. Statistics analysis displayed that four mathematical expressions were VO_2max = 0.047bw (p<0.01, R² = 0.68), VO_2max = 0.036bw+0.71 (p<0.01, R² = 0.76), VO_2max = 0.10bw^0.82 (p<0.01, R² = 0.93) and VO_2max = 0.23bw^0.66–0.48 (p<0.01, R² = 0.81) respectively. Pearson correlation coefficient showed a significant moderately negative relation between VO2maxbw and bw (r = -0.42, p<0.01), while there was no correlation between VO2maxbw0.82 and bw (r = 0.066, p = 0.41). Although statistics analysis did not fully verify the theoretical result, both dimensional and statistics analysis suggested ratio scaling distort the relationship and power function be more appropriate to describe the relationship. Additionally, we hypothesized that lean mass, rather than body weight, plays a more essential role in eliminating the gap between theoretical and experimental b values, and is more appropriate to standardize VO_2max, future studies can focus more on it.

Physiological responses during simulated 16 km recumbent handcycling time trial and determinants of performance in trained handcyclists

Purpose

To characterise the physiological profiles of trained handcyclists, during recumbent handcycling, to describe the physiological responses during a 16 km time trial (TT) and to identify the determinants of this TT performance.

Methods

Eleven male handcyclists performed a sub-maximal and maximal incremental exercise test in their recumbent handbike, attached to a Cyclus II ergometer. A physiological profile, including peak aerobic power output (PO_Peak), peak rate of oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2Peak), aerobic lactate threshold (AeLT) and PO at 4 mmol L⁻¹ (PO₄), were determined. Participants also completed a 16 km simulated TT using the same experimental set-up. Determinants of TT performance were identified using stepwise multiple linear regression analysis.

Results

Mean values of PO_Peak = 252 ± 9 W, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2Peak = 3.30 ± 0.36 L min⁻¹ (47.0 ± 6.8 mL kg⁻¹ min⁻¹), AeLT = 87 ± 13 W and PO₄ = 154 ± 14 W were recorded. The TT was completed in 29:21 ± 0:59 min:s at an intensity equivalent to 69 ± 4% PO_Peak and 87 ± 5% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2Peak. PO_Peak (r = − 0.77, P = 0.006), PO₄ (r = − 0.77, P = 0.006) and AeLT (r = − 0.68, P = 0.022) were significantly correlated with TT performance. PO₄ and PO_Peak were identified as the best predictors of TT performance (r = 0.89, P < 0.001).

Conclusion

PO_Peak, PO₄ and AeLT are important physiological TT performance determinants in trained handcyclists, differentiating between superior and inferior performance, whereas \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2peak was not. The TT took place at an intensity corresponding to 69% PO_Peak and 87% \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}$$\end{document}V˙O_2peak.

Size Exponents for Scaling Maximal Oxygen Uptake in Over 6500 Humans: A Systematic Review and Meta-Analysis

BACKGROUND

Maximal oxygen uptake ([Formula: see text] _2max) is conventionally normalized to body size as a simple ratio or using an allometric exponent < 1. Nevertheless, the most appropriate body size variable to use for scaling and the value of the exponent are still enigmatic. Studies tend to be based on small samples and can, therefore, lack precision.

OBJECTIVE

The objective of this systematic review was to provide a quantitative synthesis of reported static allometric exponents used for scaling [Formula: see text] _2max to whole body mass and fat-free mass.

METHODS

Eight electronic databases (CINAHL, Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, PubMed, Scopus, SPORTDiscus and Web of Science) were searched for relevant studies published up to January 2016. Search terms included 'oxygen uptake', 'cardiorespiratory fitness', '[Formula: see text] _2max', '[Formula: see text] _2peak', 'scaling' and all interchangeable terms. Inclusion criteria included human cardiorespiratory fitness data; cross-sectional study designs; an empirical derivation of the exponent; reported precision statistics; and reported information regarding participant sex, age and sports background, [Formula: see text] _2max protocol, whole body composition protocol and line-fitting methods. A random-effects model was used to quantify weighted pooled exponents and 95% confidence limits (Cls). Heterogeneity was quantified with the tau-statistic (τ). Meta-regression was used to quantify the impact of selected moderator variables on the exponent effect size. A 95% prediction interval was calculated to quantify the likely range of true fat-free mass exponents in similar future studies, with this distribution used to estimate the probability that an exponent would be above theorised universal values of [Formula: see text].

RESULTS

Thirty-six studies, involving 6514 participants, met the eligibility criteria. Whole body mass and fat-free mass were used as the scaling denominator in 27 and 15 studies, respectively. The pooled allometric exponent (95% Cls) was found to be 0.70 (0.64 to 0.76) for whole body mass and 0.90 (0.83 to 0.96) for fat-free mass. The between-study heterogeneity was greater for whole body mass (τ = ±0.15) than for fat-free mass (τ = ±0.11). Participant sex explained 30% of the between-study variability in the whole body mass exponent, but the influence on the fat-free mass exponent was trivial. The whole body mass exponent of 0.52 (0.40 to 0.64) for females was substantially lower than the 0.76 (0.70 to 0.83) for males, whereas the fat-free mass exponent was similar for both sexes. The effects of all other moderators were trivial. The 95% PI for fat-free mass ranged from 0.68 to 1.12. The estimated probability of a true fat-free mass exponent in a future study being greater than [Formula: see text] power scaling is 0.98 (very likely) and 0.92 (likely), respectively.

CONCLUSIONS

In this quantitative synthesis of published studies involving over 6500 humans, the whole body mass exponent was found to be spuriously low and prone to substantial heterogeneity. We conclude that the scaling of [Formula: see text] _2max in humans is consistent with the allometric cascade model with an estimated prediction interval for the fat-free mass exponent not likely to be consistent with the [Formula: see text] power laws.

Effect of inspiratory muscle training (IMT) on aerobic capacity, respiratory muscle strength and rate of perceived exertion in paraplegics

Objectives: The purpose is to study the effect of inspiratory muscle training on aerobic capacity, respiratory muscle strength and rate of perceived exertion in paraplegics.Study Design: Randomized controlled trial.Settings: Rehabilitation department in Indian Spinal Injuries Centre, New Delhi.Participants: A sample of 30 paraplegics (T1-T12) were randomly allocated into two groups: inspiratory muscle training (IMT) group and control group.Interventions: The IMT group received inspiratory muscle training for 15 minutes 5 times a week for 4 weeks whereas the control group was given breathing exercises.Outcome measures: Maximal inspiratory pressure(MIP), maximal expiratory pressure (MEP), modified Borg's scale (MBS), 12 minute wheelchair aerobic test (12MWAT), multistage fitness test (MSFT), and 6 minutes push test (6MPT).Results: Out of 30 participants, 27 completed the study. The results show that after four weeks of IMT training, there were significant improvements in mean change scores of IMT group as compared to control group. Participants in IMT group performed better on 12MWAT (P = 0.001), MSFT (P = 0.001) and 6MPT (P = 0.001). Improvements in MIP scores (P = 0.001), MEP scores (P = 0.001) and MBS scores (P = 0.004) were also seen in IMT group.Conclusion: Both groups showed significant improvements, however inspiratory muscle training was seen to be more effective than deep breathing exercises for improving aerobic capacity, respiratory muscle strength and rate of perceived exertion in paraplegics.

Peak oxygen uptake in Paralympic sitting sports: A systematic literature review, meta- and pooled-data analysis

Background

Peak oxygen uptake (VO_2peak) in Paralympic sitting sports athletes represents their maximal ability to deliver energy aerobically in an upper-body mode, with values being influenced by sex, disability-related physiological limitations, sport-specific demands, training status and how they are tested.

Objectives

To identify VO_2peak values in Paralympic sitting sports, examine between-sports differences and within-sports variations in VO_2peak and determine the influence of sex, age, body-mass, disability and test-mode on VO_2peak.

Design

Systematic literature review and meta-analysis.

Data sources

PubMed, CINAHL, SPORTDiscus^TM and EMBASE were systematically searched in October 2016 using relevant medical subject headings, keywords and a Boolean.

Eligibility criteria

Studies that assessed VO_2peak values in sitting sports athletes with a disability in a laboratory setting were included.

Data synthesis

Data was extracted and pooled in the different sports disciplines, weighted by the Dersimonian and Laird random effects approach. Quality of the included studies was assessed with a modified version of the Downs and Black checklist by two independent reviewers. Meta-regression and pooled-data multiple regression analyses were performed to assess the influence of sex, age, body-mass, disability, test mode and study quality on VO_2peak.

Results

Of 6542 retrieved articles, 57 studies reporting VO_2peak values in 14 different sitting sports were included in this review. VO_2peak values from 771 athletes were used in the data analysis, of which 30% participated in wheelchair basketball, 27% in wheelchair racing, 15% in wheelchair rugby and the remaining 28% in the 11 other disciplines. Fifty-six percent of the athletes had a spinal cord injury and 87% were men. Sports-discipline-averaged VO_2peak values ranged from 2.9 L∙min^-1 and 45.6 mL∙kg^-1∙min^-1 in Nordic sit skiing to 1.4 L∙min^-1 and 17.3 mL∙kg^-1∙min^-1 in shooting and 1.3 L∙min^-1 and 18.9 mL∙kg^-1∙min^-1 in wheelchair rugby. Large within-sports variation was found in sports with few included studies and corresponding low sample sizes. The meta-regression and pooled-data multiple regression analyses showed that being a man, having an amputation, not being tetraplegic, testing in a wheelchair ergometer and treadmill mode, were found to be favorable for high absolute and body-mass normalized VO_2peak values. Furthermore, high body mass was favourable for high absolute VO_2peak values and low body mass for high body-mass normalized VO_2peak values.

Conclusion

The highest VO_2peak values were found in Nordic sit skiing, an endurance sport with continuously high physical efforts, and the lowest values in shooting, a sport with low levels of displacement, and in wheelchair rugby where mainly athletes with tetraplegia compete. However, VO_2peak values need to be interpreted carefully in sports-disciplines with few included studies and large within-sports variation. Future studies should include detailed information on training status, sex, age, test mode, as well as the type and extent of disability in order to more precisely evaluate the effect of these factors on VO_2peak.

Effects of modified multistage field test on performance and physiological responses in wheelchair basketball players

A bioenergetical analysis of manoeuvrability and agility performance for wheelchair players is inexistent. It was aimed at comparing the physiological responses and performance obtained from the octagon multistage field test (MFT) and the modified condition in “8 form” (MFT-8). Sixteen trained wheelchair basketball players performed both tests in randomized condition. The levels performed (end-test score), peak values of oxygen uptake (VO_2peak), minute ventilation (V_Epeak), heart rate (HR_peak), peak and relative blood lactate (Δ[Lact⁻] = peak – rest values), and the perceived rating exertion (RPE) were measured. MFT-8 induced higher VO_2peak and V_Epeak values compared to MFT (VO_2peak: 2.5 ± 0.6 versus 2.3 ± 0.6 L·min⁻¹ and V_Epeak: 96.3 ± 29.1 versus 86.6 ± 23.4 L·min⁻¹; P < 0.05) with no difference in other parameters. Significant relations between V_Epeak and end-test score were correlated for both field tests (P < 0.05). At exhaustion, MFT attained incompletely VO_2peak and V_Epeak. Among experienced wheelchair players, MFT-8 had no effect on test performance but generates higher physiological responses than MFT. It could be explained by demands of wheelchair skills occurring in 8 form during the modified condition.

Changes in Body Composition and Physical Performance in Wheelchair Basketball Players During a Competitive Season

The present study analyzed the changes in body composition and physical performance in wheelchair basketball (WB) players during one competitive season. Players from a WB team competing in the first division of the Spanish League (n = 8, age: 26.5 ± 2.9 years, body mass: 79.8 ± 12.6 kg, sitting height: 91.4 ± 4.4 cm) participated in this research. The upper limbs showed a decrease in subcutaneous adipose tissue and there was an improvement in physical abilities such as sprinting with the ball (5 and 20 m), handgrip and aerobic capacity. However, the changes in physical fitness concerning sprinting without the ball and agility tests were low. It would be interesting to study the effects of implementing specific programs to improve physical performance in WB and to establish more test sessions to monitor the effects of the programs followed.

Sprint, agility, strength and endurance capacity in wheelchair basketball players

The aims of the present study were, firstly, to determine the reliability and reproducibility of an agility T-test and Yo-Yo 10 m recovery test; and secondly, to analyse the physical characteristics measured by sprint, agility, strength and endurance field tests in wheelchair basketball (WB) players. 16 WB players (33.06 ± 7.36 years, 71.89 ± 21.71 kg and sitting body height 86.07 ± 6.82 cm) belonging to the national WB league participated in this study. Wheelchair sprint (5 and 20 m without ball, and 5 and 20 m with ball) agility (T-test and pick-up test) strength (handgrip and maximal pass) and endurance (Yo-Yo 10 m recovery test) were performed. T-test and Yo-Yo 10 m recovery test showed good reproducibility values (intraclass correlation coefficient, ICC = 0.74-0.94). The WB players' results in 5 and 20 m sprints without a ball were 1.87 ± 0.21 s and 5.70 ± 0.43 s and with a ball 2.10 ± 0.30 s and 6.59 ± 0.61 s, being better than those reported in the literature. Regarding the pick-up test results (16.05 ± 0.52 s) and maximal pass (8.39 ± 1.77 m), players showed worse values than those obtained in elite players. The main contribution of the present study is the characterization of the physical performance profile of WB players using a field test battery. Furthermore, we demonstrated that the agility T-test and the aerobic Yo-Yo 10 m recovery test are reliable; consequently they may be appropriate instruments for measuring physical fitness in WB.

Submaximal exercise responses in tetraplegic, paraplegic and non spinal cord injured elite wheelchair athletes

It remains unclear whether similar exercise prescription, based on physiological markers, can be applied to subgroups of wheelchair athletes with different disabilities. Therefore, 25 wheelchair athletes, divided into three subgroups [eight tetraplegic (TETRA), nine paraplegic (PARA) and eight non spinal cord injured (NON-SCI)], performed an exercise test consisting of incremental submaximal stages, covering a range from 40% to 80% peak oxygen uptake (%VO(2peak) ). Oxygen uptake (VO(2)), heart rate (HR), blood lactate concentration (BLa) and rating of perceived exertion (RPE) were obtained for each stage. Expressed as a function of BLa, no differences were found between subgroups with respect to %VO(2peak) (group mean ± SD: 1.0 mmol/L: 53.9 ± 9.9%; 2.0 mmol/L: 70.7 ± 7.5%; 3.0 mmol/L: 78.5 ± 7.7%) and RPE [group mean (lower and upper quartile): 1.0 mmol/L: 10.8 (9.9, 12.2); 2.0 mmol/L: 13.6 (12.7, 14.3); 3.0 mmol/L: 14.9 (13.7, 16.5)]. Furthermore, no differences were found in the coefficient of determination (R(2) ) of the HR-VO(2) relationship in any of the subgroups (TETRA: 0.90 ± 0.12; PARA: 0.97 ± 0.02; NON-SCI: 0.96 ± 0.04). These results suggest that exercise prescription using measurements of VO(2), BLa or RPE can be based on the same recommendations in all the subgroups studied. This finding has added value for TETRA athletes, as it offers alternatives to HR monitoring.

Relationship between aerobic and anaerobic parameters and functional classification in wheelchair basketball players

Participation in sports for individuals with disabilities continues to gain popularity. In order to provide fair and equitable competition among persons with different disabilities and functional capacity, a separate functional classification system has been devised for each sport. The aims of the present study were to evaluate aerobic and anaerobic performance of wheelchair basketball athletes and verify a correlation with the International Wheelchair Basketball Federation functional classification system. For this, 17 highly trained male Brazilian basketball wheelchair athletes (25.4+/-4.4 years) from the national team who had taken part in the Athens 2004 Paralympic Games were assessed. These athletes were submitted to cardiopulmonary exercise testing and Wingate-like 30-s sprint test using upper limbs. The present study demonstrated that the functional classification score correlated with relative (r=0.90; P<0.0001) and absolute peak power (r=0.50; P=0.0353) and absolute mean power (r=0.93; P<0.0001) obtained from the Wingate-like 30-s sprint test and also correlated with absolute O(2) peak (r=0.68; P=0.0026) and O(2) at ventilatory threshold (r=0.71; P=0.0014), measured on cardiopulmonary exercise testing. Therefore, our findings support the functional classification created to classify athletes' functional capability on the court, which also correlated with aerobic and anaerobic performance parameters of the elite wheelchair basketball players.

Fluid intake during wheelchair exercise in the heat: effects of localized cooling garments

BACKGROUND

Wheelchair tennis players, competing in hot and humid environments, are faced with an increased risk of heat-related illness and impaired performance. This study examined the effects of head and neck cooling garments on perceptions of exertion (RPE), thermal sensation (TS), and water consumption during wheelchair exercise at 30.4 +/- 0.6 degrees C.

METHODS

Eight highly trained wheelchair tennis players (1 amputee and 7 spinal cord injured) completed two 60-min, intermittent sprint trials; once with cooling (COOL) and once without cooling (CON) in a balanced cross-over design. Players could drink water ad libitum at five predetermined intervals during each trial. Heart rate, blood lactate concentration, peak speed, TS, and RPE were recorded during the trials. Body mass and water consumption were measured before and after each trial.

RESULTS

Water consumption was lower in COOL compared with CON (700 +/- 393 mL vs. 1198 +/- 675 mL respectively; P = 0.042). Trends in data suggested lower RPE and TS under COOL conditions (N.S.). Total sweat losses ranged from 200 to 1300 mL; this equated to approximately 1% dehydration after water consumption had been accounted for when averaged across all trials. The ad libitum drinking volumes matched and, in some cases, were greater than the total sweat losses.

CONCLUSIONS

These results suggest that there is a counterproductive effect of head and neck cooling garments on water consumption. However, despite consuming volumes of water at least equivalent to total sweat loss, changes in body mass suggest an incidence of mild dehydration during wheelchair tennis in the heat.

The multi-stage fitness test as a predictor of endurance fitness in wheelchair athletes

The aims of this study were two-fold: (1) to consider the criterion-related validity of the multi-stage fitness test (MSFT) by comparing the predicted maximal oxygen uptake (.VO(2max)) and distance travelled with peak oxygen uptake (VO(2peak)) measured using a wheelchair ergometer (n = 24); and (2) to assess the reliability of the MSFT in a sub-sample of wheelchair athletes (n = 10) measured on two occasions. Twenty-four trained male wheelchair basketball players (mean age 29 years, s = 6) took part in the study. All participants performed a continuous incremental wheelchair ergometer test to volitional exhaustion to determine .VO(2peak), and the MSFT on an indoor wooden basketball court. Mean ergometer .VO(2peak) was 2.66 litres . min(-1) (s = 0.49) and peak heart rate was 188 beats . min(-1) (s = 10). The group mean MSFT distance travelled was 2056 m (s = 272) and mean peak heart rate was 186 beats . min(-1) (s = 11). Low to moderate correlations (rho = 0.39 to 0.58; 95% confidence interval [CI]: -0.02 to 0.69 and 0.23 to 0.80) were found between distance travelled in the MSFT and different expressions of wheelchair ergometer .VO(2peak). There was a mean bias of -1.9 beats . min(-1) (95% CI: -5.9 to 2.0) and standard error of measurement of 6.6 beats . min(-1) (95% CI: 5.4 to 8.8) between the ergometer and MSFT peak heart rates. A similar comparison of ergometer and predicted MSFT .VO(2peak) values revealed a large mean systematic bias of 15.3 ml . kg(-1) . min(-1) (95% CI: 13.2 to 17.4) and standard error of measurement of 3.5 ml . kg(-1) . min(-1) (95% CI: 2.8 to 4.6). Small standard errors of measurement for MSFT distance travelled (86 m; 95% CI: 59 to 157) and MSFT peak heart rate (2.4 beats . min(-1); 95% CI: 1.7 to 4.5) suggest that these variables can be measured reliably. The results suggest that the multi-stage fitness test provides reliable data with this population, but does not fully reflect the aerobic capacity of wheelchair athletes directly.

Physiology of soccer: an update

Soccer is the most popular sport in the world and is performed by men and women, children and adults with different levels of expertise. Soccer performance depends upon a myriad of factors such as technical/biomechanical, tactical, mental and physiological areas. One of the reasons that soccer is so popular worldwide is that players may not need to have an extraordinary capacity within any of these performance areas, but possess a reasonable level within all areas. However, there are trends towards more systematic training and selection influencing the anthropometric profiles of players who compete at the highest level. As with other activities, soccer is not a science, but science may help improve performance. Efforts to improve soccer performance often focus on technique and tactics at the expense of physical fitness. During a 90-minute game, elite-level players run about 10 km at an average intensity close to the anaerobic threshold (80-90% of maximal heart rate). Within this endurance context, numerous explosive bursts of activity are required, including jumping, kicking, tackling, turning, sprinting, changing pace, and sustaining forceful contractions to maintain balance and control of the ball against defensive pressure. The best teams continue to increase their physical capacities, whilst the less well ranked have similar values as reported 30 years ago. Whether this is a result of fewer assessments and training resources, selling the best players, and/or knowledge of how to perform effective exercise training regimens in less well ranked teams, is not known. As there do exist teams from lower divisions with as high aerobic capacity as professional teams, the latter factor probably plays an important role. This article provides an update on the physiology of soccer players and referees, and relevant physiological tests. It also gives examples of effective strength- and endurance-training programmes to improve on-field performance. The cited literature has been accumulated by computer searching of relevant databases and a review of the authors' extensive files. From a total of 9893 papers covering topics discussed in this article, 843 were selected for closer scrutiny, excluding studies where information was redundant, insufficient or the experimental design was inadequate. In this article, 181 were selected and discussed. The information may have important implications for the safety and success of soccer players and hopefully it should be understood and acted upon by coaches and individual soccer players.

Appropriate interpretation of aerobic capacity: allometric scaling in adult and young soccer players

OBJECTIVE

To compare aerobic capacity of young and adult elite soccer players using appropriate scaling procedures.

METHODS

Twenty four male adult (mean (SD) age 24 (2) years, weight 75.7 (7.2) kg, VO2max 66.6 (5.2) ml/lbm/min, where lbm is lean body mass in kg) and 21 youth (14 (0.4) years, 60.2 (7.3) kg, 66.5 (5.9) ml/lbm/min) elite soccer players took part in the study. Allometric equations were used to determine the relation between maximal and submaximal oxygen cost of running (running economy) and body mass.

RESULTS

Maximal and submaximal oxygen uptake increased in proportion to body mass raised to the power of 0.72 (0.04) and 0.60 (0.06) respectively. The VO2max of adult players was similar to that of the youth players when expressed in direct proportion to body mass--that is, ml/kg/min--but 5% higher (p<0.05) when expressed using appropriate procedures for scaling. Conversely, compared with seniors, youth players had 13% higher (p<0.001) energy cost of running--that is, poorer running economy--when expressed as ml/kg/min but not when expressed according to the scaling procedures.

CONCLUSIONS

Compared with the youth soccer players, VO2max in the seniors was underestimated and running economy overestimated when expressed traditionally as ml/lbm/min. The study clearly shows the pitfalls in previous studies when aerobic capacity was evaluated in subjects with different body mass. It further shows that the use of scaling procedures can affect the evaluation of, and the resultant training programme to improve, aerobic capacity.