Effect of anthropometric characteristics and socio-economic status on physical performances of pre-pubertal children living in Bolivia at low altitude

A Meta-Analysis of Sampled Maximal Aerobic Capacity Data for Boys Aged 11 Years Old or Less Obtained by Cycle Ergometry

The aim of this study was to develop distributions of VO_2max based on measured values that exist in the literature in prepubertal boys using cycle ergometry. PRISMA guidelines were followed in conducting this research. One database was searched for peak and maximal VO₂ values in healthy boys with mean age under 11 years old. Data were split into articles reporting absolute and relative VO_2max values and analyzed accordingly. Multilevel models grounded in Bayesian principles were used. We investigated associations between VO_2max and body mass, year of the study, and country of origin. Differences in "peak" and "maximal" VO₂ were assessed. Absolute VO_2max (Lmin^-1) increases with age (P ~100%) but mean relative VO_2max does not change (P ~100%). Absolute VO_2max is higher in more recent studies (P = 95.7 ± 0.3%) and mean relative VO_2max is lower (P = 99.6 ± 0.1%). Relative VO_2max in the USA is lower compared with boys from other countries (P = 98.8 ± 0.2%), but there are no differences in absolute values. Mean aerobic capacity estimates presented as "peak" values are higher than "maximal" values on an absolute basis (P = 97.5 ± 0.3%) but not on a relative basis (P = 99.6 ± 0.1%). Heavier boys have lower cardiorespiratory fitness (P ≈ 100%), and body mass seems to be increasing faster with age in the USA compared with other countries (P = 92.3 ± 0.3%). New reference values for cardiorespiratory fitness are presented for prepubertal boys obtained with cycle ergometry. This is new, as no reference values have been determined so far based on actual measured values in prepubertal boys. Aerobic capacity normalized to body weight does not change with age. Cardiorespiratory fitness in prepubertal boys is declining, which is associated with increasing body mass over the last few decades. Lastly, this study did not find any statistically significant difference in the sample's mean aerobic capacity estimates using the "peak" and "maximum" distinctions identified in the literature.

Relationships between different nutritional anthropometric statuses and health-related fitness of South African primary school children

BACKGROUND

A double burden of both under- and over-nutrition exists among South African children.

AIM

To describe associations between nutritional statuses and health-related fitness test performances.

SUBJECTS AND METHODS

Height and weight of 10 285 children (6-13 years; n = 5604 boys and 4681 girls) were measured and used to calculate body mass index (BMI) and prevalence of overweight and obesity, stunting, wasting and underweight. Physical fitness scores for standing long jump, shuttle run, sit-and-reach, sit-up (EUROFIT) and cricket ball throw were assessed. Age- and gender-specific z-scores were calculated for these variables. Physical fitness for each nutritional status group was compared to children of normal weight.

RESULTS

Compared to normal weight children, overweight and obese children scored lower on all fitness tests (p < .001), except cricket ball throw (p = .235) and sit-and-reach (p = .015). Stunted and underweight children performed poorer than normal weight children on most fitness tests (p < .001), except sit-and-reach (stunted: p = .829; underweight: p = .538) and shuttle run (underweight: p = .017). Performance of wasted children was not as highly compromised as other under-nourished groups, but they performed poorer on the cricket ball throw (p < .001).

CONCLUSIONS

When compared to normal weight children, both under- and over-nourished children performed poorer on some, but not all, health-related fitness tests.

Altitude effects on growth of indigenous children in Oaxaca, Southern Mexico

The effect of altitude of residence on the growth status of 11,454 indigenous school children 6-14 years of age in Oaxaca, southern Mexico, was examined. Indicators of living conditions (human development index [HDI], index of community nutritional risk [INR], index of marginalization [IM], index of relative isolation [II]) were regressed on z-scores for height, weight and BMI, and the residuals were regressed on altitude of residence (km). Independent of other environmental conditions, altitude negatively affected height by approximately -0.07 z-scores per kilometer altitude above sea level. The estimated average decrease in stature was 0.92 cm per kilometer elevation. BMI was significantly increased, 1.2 units per kilometer elevation, consistent with earlier studies of growth status and altitude. In contrast, weight was not affected by altitude of residence. Approximately 36% of the reduction in height and 54% of the increase in BMI were due to altitude effects; the remaining changes in height and BMI were associated with environmental factors reflected in the indices of community well-being considered.

Leg muscle power in 12-year-old black and white Tunisian football players

This study examined leg muscle power of young male Tunisian black and white football players and extended the analysis to determine whether there is a relationship between cycling peak power output (PPO) and some field tests. A total of 113 children (white group (WG) = n = 56; black group (BG) = n = 57) participated in this investigation. Anthropometric data included age, body mass (BM), height, leg length (LL), body mass index (BMI), and leg muscle volume (LMV). Cycling PPO was measured including a force-velocity test. Peak power output (PPO; W and W/kg), Fopt (optimal braking force), and Vopt (optimal velocity) were significantly higher in the WG compared with the BG (p < 0.05). However, jump and sprint performances of the BG were significantly higher than the WG (p < 0.05). Multiple stepwise regression with anthropometric variables and the extrapolated values of the force-velocity test as explanatory factors showed that 33% of the variance of PPO of BG was explained by qualitative factors that may be related to cycling skill, muscle composition, and socioeconomic and training status.

Comparison of peak muscle power between Brazilian and French girls

This study examined the muscle power of Brazilian circumpubertal girls and extended the analysis to a cross-cultural dimension. A total of 462 children, 123 Brazilian girls and 339 French girls, 9-18 years, participated in this investigation. Anthropometric data included body mass (BM), height, skinfold thicknesses, and estimated lean leg volume (LLV). All subjects completed a physical activity questionnaire. Cycling peak power was measured including the flywheel inertia of the device (CPPi). Brazilian girls self-assessed their maturation using pubic hair development. CPPi and optimal velocity (v(opt) = velocity at CPPi) increased with stages of puberty. A multiple stepwise regression with anthropometric variables as explanatory factors showed only LLV and age explaining the variance of CPPi (R2 = 0.40, P < 0.001). Therefore, 60% of the variance of CPPi in Brazilian girls was related to undetermined qualitative individual factors, which may be related to cycling skill. Even when normalized for anthropometric variables, the anaerobic performance (CPPi and v(opt)) of Brazilian girls was significantly lower than a cohort of French girls. The latter demonstrated a high participation in sport and training activities, while 50% of the Brazilian girls had only physical education classes in the form of regular physical activity. Moreover, most of the Brazilian girls demonstrated an ineffective sprint cycling skill. The data suggest that motor learning is an important issue in muscle power assessment and might, therefore, partially explain peak power differences in Brazilian compared with French girls.