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

Abstract

The influence of training status on the oxygen uptake ($\dot{V}{\text{O}}_{ 2}$) response to heavy intensity exercise in pubertal girls has not previously been investigated. We hypothesised that whilst training status-related adaptations would be evident in the $\dot{V}{\text{O}}_{ 2}$, heart rate (HR) and deoxyhaemoglobin ([HHb]) kinetics of pubertal swimmers during both lower and upper body exercise, they would be more pronounced during upper body exercise. Eight swim-trained (T; 14.2 ± 0.7 years) and eight untrained (UT; 14.5 ± 1.3 years) girls completed a number of constant-work-rate transitions on cycle and upper body ergometers 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 (τ) was significantly shorter in the trained girls during both cycle (T: 21 ± 6 vs. UT: 35 ± 11 s; P < 0.01) and upper body exercise (T: 29 ± 8 vs. UT: 44 ± 8 s; P < 0.01). The $\dot{V}{\text{O}}_{ 2}$ slow component was not influenced by training status. The [HHb] τ was significantly shorter in the trained girls during both cycle (T: 12 ± 2 vs. UT: 20 ± 6 s; P < 0.01) and upper body exercise (T: 13 ± 3 vs. UT: 21 ± 7 s; P < 0.01), as was the HR τ (cycle, T: 36 ± 5 vs. UT: 53 ± 9 s; upper body, T: 32 ± 3 vs. UT: 43 ± 2; P < 0.01). This study suggests that both central and peripheral factors contribute to the faster $\dot{V}{\text{O}}_{ 2}$ kinetics in the trained girls and that differences are evident in both lower and upper body exercise.