AEROBIC FITNESS OF PREPUBESCENT CHILDREN

This study was designed to enhance understanding of the assessment and interpretation of the aerobic fitness of prepubertal children. Written informed consent to participate was obtained from 70% of the children in year six of the 15 state schools in the city of Exeter. Twenty-five per cent of the eligible children in each school were randomly selected from those who volunteered. The data reported here are those obtained from the 111 boys(11.1 SD 0.4 years) and 53 girls (10.9 SD 0.3 years) classified as Tanner stage 1 in both pubic hair rating and either genitalia rating (boys) or breast rating (girls). Peak oxygen uptake (peak Vover dotO(2)) was determined using a discontinuous, incremental protocol on a treadmill. Only a minority of children demonstrated a levelling-off or plateau in Vover dotO(2) despite an increase in exercise intensity. There was no evidence to suggest that the children who demonstrated a Vover dotO(2) plateau had significantly (p<0.05)higher peak Vover dotO(2), peak heart rate, peak respiratory exchange ratio or peak blood lactate than those children who did not demonstrate a plateau in Vover dotO(2). These findings indicate that a Vover dotO(2) plateau should not be used as a requirement for defining a maximal exercise test with prepubertal children. Boys had a significantly (p<0.01) higher peak Vover dotO(2) than girls, whether expressed in 1 . min(-1) (1.78 vs 1.46) or in relation to body mass (51 vs 45 ml . kg(-1). min(-1)). The results compare favourably with those of similarly aged children from other countries, but why prepubescent boys have significantly higher (13.3%) mass-related peak lie, than prepubescent girls is not readily apparent. Although conventional, the expression of peak Vover dotO(2) as per body mass ratio may not adequately partition out body-size differences. The influence of body mass was therefore removed using a linear adjustment scaling model and a log-linear model, but the boys' peak Vover dotO(2) remained significantly (p<0.01) higher than the girls' peak Vover dotO(2) with the difference now being 16.0% and 16.2%, respectively.