Resumen de Faster Pulmonary Oxygen Uptake Kinetics in Trained versus Untrained Male Adolescents

Simon Marwood, Denise Roche, T. Rowland, Max Garrard, Viswanath B. Unnithan

• Exercise training results in a speeding of pulmonary oxygen uptake (V[spacing dot above]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[spacing dot above]O2 and muscle deoxygenation kinetics in trained and untrained male adolescents.

  Methods: Sixteen trained (15 +/- 0.8 yr, V[spacing dot above]O2peak = 54.7 +/- 6.2 mL[middle dot]kg-1[middle dot]min-1, self-assessed Tanner stage range 2-4) and nine untrained (15 +/- 0.6 yr, V[spacing dot above]O2peak = 43.1 +/- 5.2 mL[middle dot]kg-1[middle dot]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[spacing dot above]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[spacing dot above]O2 kinetics in male adolescents, although inherent capabilities cannot be ruled out. Because muscle deoxygenation kinetics were unchanged, it is likely that faster V[spacing dot above]O2 kinetics were due to adaptations to both the cardiovascular system and the peripheral musculature.