Oxygen Uptake Kinetics During Moderate and Heavy Intensity Exercise in Humans: The Influence of Hypoxia and Training Status

• Published in: International journal of sports medicine 2005-06, Vol.26 (5), p.356-362
• Main Authors: Cleuziou, C., Perrey, S., Lecoq, A. M., Candau, R., Courteix, D., Obert, P.
• Format: Article
• Language: English
• Subjects: Adult; Biological and medical sciences; Cross-Sectional Studies; Exercise - physiology; Fundamental and applied biological sciences. Psychology; Heart Rate - physiology; Humans; Hypoxia - physiopathology; Kinetics; Male; Oxygen Consumption - physiology; Physical Education and Training; Physiology & Biochemistry; Running - physiology; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 0172-4622; 1439-3964
• DOI: 10.1055/s-2004-821158

Abstract This study examined the influence of moderate hypoxia on the oxygen uptake (V·O 2 ) kinetic response (primary time constant and slow component amplitude) during moderate and heavy cycle exercise in twenty-seven male subjects with various training status. Nine endurance trained (21.5 ± 2.6 yr), nine sprint trained (22.9 ± 5.7 yr), and nine untrained controls (24.0 ± 4.4 yr) completed incremental tests to exhaustion in normoxia (inspired gas concentration or FIO 2 = 21 % O 2 ) and hypoxia (FIO 2 = 13 % O 2 ) to establish the FIO 2 -specific ventilatory threshold (VT) and maximal VO 2 . Subsequently, the subjects performed repeated constant work rate cycling exercises during 7 min at moderate intensity (80 % of FIO 2 -specific VT) and heavy intensity (midway between the FIO 2 specific VT and maximal VO 2 ). Pulmonary gas exchange was measured breath-by-breath during all exercise sessions. For both moderate and heavy intensities, the time constant of the primary VO 2 component was significantly (p < 0.05) slowed by ∼ 25 to 30 % in hypoxia compared to normoxia to the same extent in the three groups. Hypoxia produced a more important decrease in the amplitude of the slow component in endurance athletes (- 36 %) than in sprinters (- 30 %) and controls (- 12 %). These results suggest that both primary and slow components of VO 2 kinetics during the adjustment to moderate- and heavy-intensity exercise are sensitive to hypoxia while training status tended to modulate partly the slow component amplitude.