Abstract
Closing volume (CV) along with vital capacity (VC), expiratory reserve volume (ERV), and residual volume (RV) were determined on seven swimmers and seven physical education students in three positions (standing, supine, and prone) both in air and during head out water immersion. Lung volumes were also measured during bicycling and swimming to clarify if airway closure, as measured by CV, occurred during tidal ventilation in exercise.
CV/VC and CC/TLC in standing position in air were significantly lower in our subjects than standard values obtained by Buist, A.S, and Leblance, P. This may suggest that the lung elastic recoil was increased by physical training.
There was no difference among CV's measured in three positions, but CV increased when subject was immersed in water.
Tidal volume (TV) in rest sitting position in air was in middle level of VC, and expanded evenly toward both expiratory and inspiratory sides with the increase of work load in bicycling. The level of tidal ventilation in rest supine position in air was lower than that in sitting position, and the increase in TV took place at the expense of IRV rather than ERV. FRC fell at rest in water, and the mean respiratory level shifted toward inspiratory side to increase ERV and FRC and to decrease IRV as the smimming speed increased.
FRC and CC got close in supine bicycling, suggesting the increased probability of airway closure within the range of tidal ventilation level. CC was much less than FRC in other types of exercise.
