Response of lung volumes and ventilation to posture change and upright exercise

Abstract

Variations in size of the various lung volumes due to changes in body position and as a consequence of treadmill exercise were studied in five normal males. Assumption of the upright posture was associated with highly significant increases in total lung capacity, vital capacity, expiratory reserve volume, and residual volume as compared to resting supine values. Level walking was associated with a decrease of expiratory reserve volume, but a further expansion of residual volume. Vital capacity decreased slightly, but total lung capacity increased by virtue of the proportionately large residual volume increases. Elevation of the treadmill to 4° resulted in slight decreases in all lung volumes, total lung capacity evidencing a barely significant decline. Positional changes in ventilation are described, and on the basis of the “lung clearance index” an increased efficiency of ventilation is seen in the upright posture. Factors possibly operative in these alterations are discussed. Submitted on February 21, 1962