Pulmonary oxygen uptake kinetics in trained and untrained male adolescents

Exercise training results in a speeding of pulmonary oxygen uptake (VO2) kinetics at the onset of exercise in adults, however only limited research has been conducted with physiologically immature subjects.

PURPOSE: The aim of the present study was to examine VO2 and muscle deoxygenation kinetics in trained and untrained male adolescents. METHOD: 16 trained (14.5 ± 0.2 yrs, VO2peak: 54.7 ± 1.6 ml.kg-1.min-1, Self-assessed Tanner stage range 2 - 4) and 9 untrained (15.4 ± 0.2 yrs, VO2peak: 43.1 ± 1.7 ml.kg-1.min-1, Tanner stage range 2 - 4) male adolescents performed two 6-min exercise transitions from a 3-min baseline of 10W to a workload equivalent to 80% lactate threshold separated by a minimum of 1 hour passive rest. Oxygen uptake (breath-by-breath) and muscle deoxygenation (deoxyhaemoglobin signal from near infrared spectroscopy) were measured continuously throughout baseline and exercise transition.

RESULTS: The time constant of the fundamental phase of VO2 kinetics was significantly faster in trained versus untrained subjects (Trained: 22.3 ± 1.8 s vs Untrained: 29.8 ± 2.8 s, p=0.03). In contrast, neither the time constant (Trained: 9.7 ± 0.7 s vs Untrained: 10.1± 1.1 s, p=0.78) or mean response time (Trained: 17.4 ± 0.6 s vs Untrained: 18.3 ± 0.8 s, p=0.39) of muscle deoxygenation kinetics was altered according to training status.

CONCLUSION: The present data suggest that exercise training results in faster VO2 kinetics in male adolescents, though inherent capabilities cannot be ruled out. Since muscle deoxygenation kinetics were unchanged, it is likely that faster VO2 kinetics were due to adaptations to both the cardiovascular system and the peripheral musculature.