Rapid Restitution of the Lung Functions Following Short-Term Breath- Holding During Moderate Intensity Cycling Exercise

ABSTRACT

Short periods of breath-holding (BH) occur frequently during various kinds of sports activities. Increased minute oxygen uptake (VO2), increased minute carbon dioxide output (VCO2) and increased minute ventilation (VE) are some of the typical responses just after breaking the BH and resuming breathing and these parameters return to their steady levels over time. This study examined the properties of the restitution processes of lung functions after BH. Exercise tests were carried out with a bicycle ergometer for seven healthy male athletes and the ventilation activities and expired gases were measured with a breath-by-breath based aeromonitor. The respiratory responses to 25 s BH were tested during continuous cycling at three exercise loads (2 W, 22 W and 102 W). A single exponential decay function with two parameters: initial amplitude (A) and time constant (τ), was fitted to the data of VO2, VCO2, VE, expiratory tidal volume (TVE) and respiratory rate (RR) after cessation of the BH. It was found that, except for RR, A was increased and τ was decreased with increasing the exercise intensity. The A of VCO2 was smaller and τ was longer than those of VO2 at all load intensities. The difference in the time courses of VO2 and VCO2 may be explained by the different buffer mechanisms of oxygen and carbon dioxide within the body.