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Comparisons of physical fitness measures between children or within group measures over time are potentially confounded by differences in body size. We compared measures of strength (handgrip) and aerobic fitness (running-speed [20m shuttle-run]) of 10.0-15.9 year-olds from Dar es Salaam, Tanzania (n = 977) with schoolchildren from England (n = 1014) matched for age and sex. Differences in fitness were analyzed using general linear models, with allometric scaling for body size (mass and stature) and further adjustments for physical activity. Mean handgrip of Tanzanians was lower than English youth (F = 165.0, P

Regular participation in strength and conditioning activities positively correlates with health-related benefits in sports (team and individual). Maturity offset (MO) is a recognized parameter in fitness outcome assessment. The aims of the present study are to analyze cross-sectional allometric development of motor performances in a sample of adolescents and relate scaled motor performance to the estimated amount and type of physical activity and biological maturity status in 771 subjects aged 14–19 years. Three physical fitness components were evaluated using field tests (standing broad jump, sit-ups, shuttle run). Extra hours of sport after school (EHS) and MO were the covariates. The model to predict the physical performance variables was: Y = a · Mk1· Hk2· WCk3· exp(b · EHS + c · MO) · ε. Results suggest that having controlled for body size and body shape, performing EHS and being an early developer (identified by a positive MO slope parameter) benefits children in physical fitness and motor performance tasks.

Background Professional dancers are at risk of developing low bone mineral density (BMD). However, whether low BMD phenotypes already exist in pre-vocational dance students is relatively unknown. Aim To cross-sectionally assess bone mass parameters in female dance students selected for professional dance training (first year vocational dance students) in relation to aged- and sex-matched controls. Methods 34 female selected for professional dance training (10.9yrs ±0.7) and 30 controls (11.1yrs ±0.5) were examined. Anthropometry, pubertal development (Tanner) and dietary data (3-day food diary) were recorded. BMD and bone mineral content (BMC) at forearm, femur neck (FN) and lumbar spine (LS) were assessed using Dual-Energy X-Ray Absorptiometry. Volumetric densities were estimated by calculating bone mineral apparent density (BMAD). Results Dancers were mainly at Tanner pubertal stage I (vs. stage IV in controls, p

The purpose of this study was to investigate the effects of playing position, pitch location, team ability and opposition ability on technical performance variables (pass, cross, corner, free kick accuracy) of English Premier League Soccer players in difference score line states. A validated automatic tracking system (Venatrack) was used to code player actions in real time for passing accuracy, cross accuracy, corner accuracy and free kick accuracy. In total 376 of the 380 games played during the 2011-12 English premier League season were recorded, resulting in activity profiles of 570 players and over 35'000 rows of data. These data were analysed using multi-level modelling. Multi-level regression revealed a "u" shaped association between passing accuracy and goal difference (GD) with greater accuracy occurring at extremes of GD e.g., when the score was either positive or negative. The same pattern was seen for corner accuracy away from home e.g., corner accuracy was lowest when the score was close with the lowest accuracy at extremes of GD. Although free kicks were not associated with GD, team ability, playing position and pitch location were found to predict accuracy. No temporal variables were found to predict cross accuracy. A number of score line effects were present across the temporal factors which should be considered by coaches and managers when preparing and selecting teams in order to maximise performance. The current study highlighted the need for more sensitive score line definitions in which to consider score line effects.

Stepping is a convenient form of scalable high-intensity interval training (HIIT) that may lead to health benefits. However, the accurate personalised prescription of stepping is hampered by a lack of evidence on optimal stepping cadences and step heights for various populations. This study examined the acute physiological responses to stepping exercise at various heights and cadences in young (n = 14) and middle-aged (n = 14) females in order to develop an equation that facilitates prescription of stepping at targeted intensities. Participants completed a step test protocol consisting of randomised three-minute bouts at different step cadences (80, 90, 100, 110 steps·min-1) and step heights (17, 25, 30, 34 cm). Aerobic demand and heart rate values were measured throughout. Resting metabolic rate was measured in order to develop female specific metabolic equivalents (METs) for stepping. Results revealed significant differences between age groups for METs and heart rate reserve, and within-group differences for METs, heart rate, and metabolic cost, at different step heights and cadences. At a given step height and cadence, middle-aged females were required to work at an intensity on average 1.9 ± 0.26 METs greater than the younger females. A prescriptive equation was developed to assess energy cost in METs using multilevel regression analysis with factors of step height, step cadence and age. Considering recent evidence supporting accumulated bouts of HIIT exercise for health benefits, this equation, which allows HIIT to be personally prescribed to inactive and sedentary women, has potential impact as a public health exercise prescription tool.

Children from developed and developing countries differ in their body size and shape due to marked differences across their life history caused by social, economic and cultural differences which are also linked to their motor performance (MP). We used allometric models to identify size/shape characteristics associated with MP tests between Brazilian and Peruvian schoolchildren. A total of 4,560 subjects, 2,385 girls and 2,175 boys aged 9-15 years were studied. Height and weight were measured; biological maturation was estimated with the maturity offset technique; MP measures included the 12 minute run (12MR), handgrip strength (HG), standing long jump (SLJ) and the shuttle run speed (SR) tests; physical activity (PA) was assessed using the Baecke questionnaire. A multiplicative allometric model was adopted to adjust for body size differences across countries. Reciprocal ponderal index (RPI) was found to be the most suitable body shape indicator associated with the 12MR, SLJ, HG and SR performance. A positive maturation offset parameter was also associated with a better performance in SLJ, HG and SR tests. Sex differences were found in all motor tests. Brazilian youth showed better scores in MP than their Peruvian peers, even when controlling for their body size differences The current study identified the key body size associated with four body mass-dependent MP tests. Biological maturation and PA were associated with strength and motor performance. Sex differences were found in all motor tests, as well as across countries favoring Brazilian children even when accounting for their body size/shape differences.

Objective This study compared actual 6 minute walk test (6MWT) performance with predicted 6MWT using previously validated equations and then determined whether allometric modelling offers a sounder alternative to estimating 6MWT in adults aged 50–80 years. Methods We compared actual 6MWT performance against predicted 6MWT in 125 adults aged 50–85 years (62 male, 63 female). In a second sample of 246 adults aged 50–85 years (74 male, 172 female), a new prediction equation for 6MWT performance was developed using allometric modelling. This equation was then cross validated using the same sample that the other prediction equations were compared with. Results Significant relationships were evident between 6MWT actual and 6MWT predicted using all of the commonly available prediction equations (all P0.05). A series of paired t-tests indicated significant differences between 6MWT actual and 6MWT predicted for all available prediction equations (all P

OBJECTIVE: Magnetic resonance spectroscopy (MRS) provides an exceptional opportunity for the study of in vivo metabolism. MRS is widely used to measure phosphorus metabolites in trained muscle, although there are no published data regarding its reproducibility in this specialized cohort. Thus, the aim of this study was to assess the reproducibility of (31)P-MRS in trained skeletal muscle. METHODS: We recruited fifteen trained men (VO(2)peak = 4.7±0.8 L min(-1)/58±8 mL kg(-1) min(-1)) and performed duplicate MR experiments during plantar flexion exercise, three weeks apart. RESULTS: Measures of resting phosphorus metabolites were reproducible, with 1.7 mM the smallest detectable difference in phosphocreatine (PCr). Measures of metabolites during exercise were less reliable: exercising PCr had a coefficient of variation (CV) of 27% during exercise, compared with 8% at rest. Estimates of mitochondrial function were variable, but experimentally useful. The CV of PCr(1/2t) was 40%, yet much of this variance was inter-subject such that differences of

The public health challenges associated with rapid population ageing are likely to be exacerbated by poor physical activity levels. The purpose of this study was to identify correlates of physical inactivity in a population-representative sample of older adults in Ireland. This paper reports a secondary analysis of data from 4892 adults aged 60+ from the Irish Longitudinal Study on Ageing (TILDA). TILDA includes an assessment of the mental and physical health, and social and financial circumstances of participants assessed in a home interview and self-completion questionnaire. Chi squared statistics and forced entry logistic regression were used to identify factors associated with physical inactivity. Females were over twice as likely to be inactive as their male counterparts (Odds Ratio 2.2). Increasing old age was associated with inactivity among males and females. Those who reported above secondary level education, no reported falls in the last year and no fear of falling were less likely to be physically inactive. While older adults who noted poor/fair self-reported health, that they did not look after grandchildren, did not own a car or did not attend a course were also more likely to be inactive than those who reported positively for these items. Gender displayed a strong but often contrasting influence on factors that affect physical activity among older adults. Among females, living alone or in a rural area, retirement, fair/poor emotional health and activity being limited by illness were all significantly associated with inactivity. While cohabiting, being employed and residing in an urban area were related to low levels of activity in males. Our findings identify specific groups of the older Irish population who may be at particular risk of physical inactivity and thereby the associated physiological and psychological hazards. These results can support the development of tailored interventions to promote healthy ageing.