Faster pulmonary oxygen uptake kinetics in trained versus untrained male adolescents

Exercise training results in a speeding of pulmonary oxygen uptake (V˙O2) kinetics at the onset of exercise in adults; however, only limited research has been conducted with children and adolescents.

Purpose: The aim of the present study was to examine V˙O2 and muscle deoxygenation kinetics in trained and untrained male adolescents.

Methods: Sixteen trained (15 ± 0.8 yr, V˙O2peak = 54.7 ± 6.2 mL·kg−1·min−1, self-assessed Tanner stage range 2-4) and nine untrained (15 ± 0.6 yr, V˙O2peak = 43.1 ± 5.2 mL·kg−1·min−1, Tanner stage range 2-4) male adolescents performed two 6-min exercise transitions from a 3-min baseline of 10 W to a workload equivalent to 80% lactate threshold separated by a minimum of 1 h of passive rest. Oxygen uptake (breath-by-breath) and muscle deoxygenation (deoxyhemoglobin signal from near-infrared spectroscopy) were measured continuously throughout baseline and exercise transition.

Results: The time constant of the fundamental phase of V˙O2 kinetics was significantly faster in trained versus untrained subjects (trained: 22.3 ± 7.2 s vs untrained: 29.8 ± 8.4 s, P = 0.03). In contrast, neither the time constant (trained: 9.7 ± 2.9 s vs untrained: 10.1 ± 3.4 s, P = 0.78) nor the mean response time (trained: 17.4 ± 2.5 s vs untrained: 18.3 ± 2.3 s, P = 0.39) of muscle deoxygenation kinetics differed with training status.

Conclusions: The present data suggest that exercise training results in faster V˙O2 kinetics in male adolescents, although inherent capabilities cannot be ruled out. Because muscle deoxygenation kinetics were unchanged, it is likely that faster V˙O2 kinetics were due to adaptations to both the cardiovascular system and the peripheral musculature.