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\ud kinetics in trained and untrained male adolescents. Methods: Sixteen trained (15 T 0.8 yr, V˙ O2peak = 54.7 T 6.2 mLIkgj1Iminj1, selfassessed Tanner stage range 2–4) and nine untrained (15 T 0.6 yr, V˙ O2peak = 43.1 T 5.2 mLIkgj1Iminj1, Tanner stage range 2–4) male\ud 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\ud of the fundamental phase of V˙ O2 kinetics was significantly faster in trained versus untrained subjects (trained: 22.3 T 7.2 s vs untrained:29.8 T 8.4 s, P = 0.03). In contrast, neither the time constant (trained: 9.7 T 2.9 s vs untrained: 10.1 T 3.4 s, P = 0.78) nor the mean\ud response time (trained: 17.4 T 2.5 s vs untrained: 18.3 T 2.3 s, P = 0.39) of muscle deoxygenation kinetics differed with training status.\ud 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\ud to adaptations to both the cardiovascular system and the peripheral musculature