Relationship between peak oxygen uptake and regional body composition in Japanese subjects

Purpose： To investigate the link between peak oxygen uptake and regional body composition by dual energy X-ray absorptiometry （DEXA） in Japanese subjects. Methods： A total of 93 men （42.2 ± 12.3 years old） and 106 women （43.5 ± 12.3 years old） were enrolled in this cross-sectional investigation study. Peak oxygen uptake was measured by the breath-by-breath method. Regional body composition i.e., body fat mass, lean body mass, and body fat percentage was evaluated using DEXA. In addition, metabolic risk parameters were also evaluated. Results： Peak oxygen uptake was 37.6± 8.7 mL/kg/min in men and 31.1 ± 6.4 mL/kg/min in women, and decreased with age in both genders. Peak oxygen uptake was significantly correlated with total body fat percentage （men： r = -0.684, p 〈 0.0001; women： r = -0.681, p 〈 0.0001）. These associations remained even after adjusting for age and total lean body mass. However, peak work rate was positively and significantly correlated with leg lean body mass. Conclusion： Peak oxygen uptake was closely correlated with total body fat percentage in both genders. Aerobic exercise as well as leg resistance training might be useful for improving peak oxygen uptake in Japanese subjects. Copyright

The Development of Aerobic and Anaerobic Fitness with Reference to Youth Athletes

Purpose To challenge current conventions in paediatric sport science and use data from recent longitudinal studies to elu-cidate the development of aerobic and anaerobic fitness,with reference to youth athletes.Methods(1)To critically review the traditional practice of ratio scaling physiological variables with body mass and,(2)to use multiplicative allometric models of longitudinal data,founded on 1053(550 from boys)determinations of 10-17-year-olds’peak oxygen uptake(VO2)and 763(405 from boys)determinations of 11-17-year-olds’peak power output(PP)and mean power output(MP),to investigate the development of aerobic and anaerobic fitness in youth.Results The statistical assumptions underpinning ratio scaling of physiological variables in youth are seldom met.Multiplicative allometric modelling of longitudinal data has demonstrated that fat free mass(FFM)acting as a surrogate for active muscle mass,is the most powerful morphological influence on PP,MP,and peak VO2.With FFM appropriately controlled for,age effects remain significant but additional,independent effects of maturity status on anaerobic and aerobic fitness are negated.Conclusions Ratio scaling of physiological variables with body mass is fallacious,confounds interpretation of the develop-ment of anaerobic and aerobic fitness,and misleads fitness comparisons within and across youth sports.Rigorous evalua-tion of the development of anaerobic and aerobic fitness in youth requires longitudinal analyses of sex-specific,concurrent changes in age-and maturation-driven morphological covariates.Age and maturation-driven changes in FFM are essential considerations when evaluating the physiological development of youth athletes.