Competitive child cyclists exhibited greater VO2max (60.0 vs 47.0 mL/kg/min) and maximal stroke index (76 vs 60 mL/m2) than untrained boys, driven by higher resting stroke volumes.
Cross-Sectional (n=46)
Do highly trained child endurance athletes exhibit different hemodynamic responses to progressive cycle exercise compared to untrained age-matched boys?
In child endurance athletes, a higher VO2max is primarily driven by a greater resting and maximal stroke volume rather than enhanced stroke volume augmentation or arteriovenous oxygen extraction during exercise.
Absolute Event Rate: 60% vs 47%
PURPOSE: Cardiovascular responses to exercise in highly trained child endurance athletes have not been well-defined. This study compared hemodynamic responses with progressive cycle exercise in seven competitive child cyclists (mean age 11.9 yr) compared with 39 age-matched untrained boys. METHODS: Doppler echocardiography and gas exchange variables were utilized to assess cardiovascular changes during submaximal and maximal exercise. RESULTS: Mean VO2max was 60.0 (+/-6.0) and 47.0 (+/-5.8) mL x kg(-1) x min(-1) in the cyclists and nonathletes, respectively. At rest and maximal exercise, the cyclists demonstrated greater stroke index than the untrained subjects (resting mean 59 (+/-6) vs 44 (+/-9) mL x m(-2); maximal mean 76 (+/-6) vs 60 (+/-11) mL x m(-2)), but the ratio of maximal:rest stroke index was similar in both groups (1.31 for cyclists, 1.41 for nonathletes). Both groups showed a plateau in stroke volume beyond low-intensity work levels. No significant difference was observed in maximal arteriovenous oxygen difference. CONCLUSIONS: These findings indicate that 1) maximal stroke volume is the critical determinant of the high VO2max in child cyclists and 2) factors that influence resting stroke volume are important in defining VO2max differences between child endurance athletes and untrained boys.
Rowland et al. (Sat,) conducted a cross-sectional in Healthy (n=46). Competitive cycling training vs. Untrained boys was evaluated on VO2max (mL x kg(-1) x min(-1)). Competitive child cyclists exhibited greater VO2max (60.0 vs 47.0 mL/kg/min) and maximal stroke index (76 vs 60 mL/m2) than untrained boys, driven by higher resting stroke volumes.