Little is known regarding the physiological determinants of maximal oxygen uptake (VO2max) in children. A group of 39 healthy sixth-grade boys (mean age, 12.2 years) underwent maximal cycle testing with determination of cardiovascular factors using Doppler echocardiography as well as standard gas exchange variables. Maximal stroke index was related to VO2max/kg (r=0.52, p < .05), but no relationship was observed between VO2max/kg and either maximal heart rate or calculated maximal arteriovenous oxygen difference. Values of maximal stroke index were closely related to those at rest (r = 0.67). These findings suggest that factors influencing resting stroke volume are primarily responsible for inter-individual differences in VO2max per kg in healthy, non-athletically-trained boys.
T. Rowland is with the Department of Pediatrics at Baystate Medical Center, Springfield, MA 01199. G. Kline and D. Goff are with the Department of Exercise Science, University of Massachusetts, Amherst, MA 01003. L. Martel and L. Ferrone are with the Agawam Public Schools. Patty Freedson served as guest editor in the review process for this manuscript.