Changes in oxygen consumption of young boys during growth and running training

Fourteen boys, aged 10–15, were tested on five occasions during 22 months of distance-running training. Semi-annually, height and weight were recorded as were performances for 1− and 2-mile races. Sub-maximal and maxV̇o2 were also determined from expired gas samples which were collected during treadmill running. After 22 months, average growth was 11.2 cm and 9.2 kg. MaxV̇o3 increased from 2331 ml to 2839 ml; maxV̇o2/kg did not change significantly from a mean of 59.5 ml/kg per minute. During the 12-month period of greatest growth (6.4 cm and 5.9 kg), maxV̇o2 increased 295 ml, a. 50 ml increase per kg increase in weight. Again no change was measured in maxV̇o2/kg. Average improvement in running performance was 32 seconds in the mile and 63 seconds in 2 miles. Steady-state Vo2 (ml/kg per min) during running at 202 m/min gradually diminished from 52.0 in the initial test series to 45.5 22 months later. This apparent improvement in running efficiency, which was to a great degree a function of growth, was believed to be (along with possible increased anaerobic activity) mainly responsible for better running performance.