Influence of training status and exercise modality on pulmonary O₂ uptake kinetics in pre-pubertal girls

Abstract

The limited available evidence suggests that endurance training does not influence the pulmonary oxygen uptake ($\dot{V}{\text{O}}_{2}$) kinetics of pre-pubertal children. We hypothesised that, in young trained swimmers, training status-related adaptations in the $\dot{V}{\text{O}}_{2}$ and heart rate (HR) kinetics would be more evident during upper body (arm cranking) than during leg cycling exercise. Eight swim-trained (T; 11.4 ± 0.7 years) and eight untrained (UT; 11.5 ± 0.6 years) girls completed repeated bouts of constant work rate cycling and upper body exercise at 40% of the difference between the gas exchange threshold and peak $\dot{V}{\text{O}}_{2}$. The phase II $\dot{V}{\text{O}}_{2}$ time constant was significantly shorter in the trained girls during upper body exercise (T: 25 ± 3 vs. UT: 37 ± 6 s; P < 0.01), but no training status effect was evident in the cycle response (T: 25 ± 5 vs. UT: 25 ± 7 s). The $\dot{V}{\text{O}}_{2}$ slow component amplitude was not affected by training status or exercise modality. The time constant of the HR response was significantly faster in trained girls during both cycle (T: 31 ± 11 vs. UT: 47 ± 9 s; P < 0.01) and upper body (T: 33 ± 8 vs. UT: 43 ± 4 s; P < 0.01) exercise. The time constants of the phase II $\dot{V}{\text{O}}_{2}$ and HR response were not correlated regardless of training status or exercise modality. This study demonstrates for the first time that swim-training status influences upper body $\dot{V}{\text{O}}_{2}$ kinetics in pre-pubertal children, but that cycle ergometry responses are insensitive to such differences.