Effect of hyperventilation on oxygen uptake kinetics during cycling exercise

摘要

This study aimed to investigate the effect of hyperventilation (induced by controlled tachypnea) on the kinetics of oxygen uptake during cycling exercise. The subjects in this study performed 4 min of baseline cycling exercise at 10 W, followed by cycling exercise for 6 min at intensities of anaerobic threshold (AT) plus 40% of the difference between the AT and the peak pulmonary oxygen uptake (heavy exercise). Throughout the experiment, each subject maintained his respiratory rate at 20, 30, or 60 breaths/min. The pulmonary gas exchange and heart rate were measured breath by breath, and the oxy- and deoxyhemoglobin concentrations of the vastus lateral is muscles were estimated using near-infrared spectroscopy at 1 Hz. Kinetic analysis showed that the time constant of oxygen uptake at the onset of heavy exercise decreased as the respiratory rate increased. Active muscle deoxygenation did not differ significantly according to the respiratory rate. This study suggests the kinetics of oxygen uptake at the onset of heavy exercise become faster as the respiratory rate increases.