Submaximal aerobic running economy and treadmill performance in prepubertal boys.

Although the determinants of running economy and its relationship to endurance performance have been evaluated in adults, little data are available in pediatric subjects. Twenty-eight prepubertal boys with diverse athletic abilities underwent progressive maximal treadmill testing. Running economy was defined as (1) VO2 at 9.6 kph and (2) VO2 expenditure for increasing running speed 1.6 kph (delta VO2). Treadmill running times ranged from 12.6 to 23.0 min. Mean VO2 at 6 mph was 48.7 m.kg-1.min-1 (SD 4.3) and delta VO2 averaged 6.8 m.kg-1.min-1 (SD 1.7). VO2max correlated closely to treadmill time. Treadmill endurance times were significantly related to running economy by both definitions; submaximal VO2 levels did not, however, correlate with maximal aerobic power. Delta VO2 was associated with stride frequency, but no other relationships were observed between economy and height, age, respiratory exchange ratio, ventilatory equivalent for oxygen, stride length: leg length ratio, or body surface area: mass ratio. These findings suggest that among older prepubertal boys, greater running economy is associated with superior treadmill endurance performance and that stride frequency may influence submaximal VO2 expenditure in children.