Effects of physical training on cardiorespiratory fitness in children

Changes in submaximal and maximal HR and [vdot]0₂ as a result of 8 wk of interval training were studied in boys aged 10-12; 13 boys trained while 11 acted as controls. Training HR’s averaged approximately 90% of the mean maximal HR. [vdot]O₂ max did not change significantly with training. The apparently high threshold for a training effect on the [vdot]O₂ max in children is probably related to their naturally active lives: the stresses induced by short-term training are probably small as compared to the overall activities of children. On the other hand, submaximal heart rate during bicycle and treadmill exercise decreased significantly with training. The O₂ cost of these submaximal tasks remained unchanged. The findings suggest that the use of [vdot]O₂ max as the only training criterion for cardiorespiratory fitness may be misleading. Since most work tasks proceed at a submaximal rate, and a training-induced improvement in submaximal response was demonstrated without improvements at maximal effort, perhaps submaximal physiological and performance measures are more important than maximal ones in the assessment of cardiorespiratory fitness.