Effects of lung volume on the depth of center of gravity, trunk inclination angle, and projected frontal area during front crawl swimming

Abstract

The purpose of this study was to examine the effect of lung volume on the depth of the swimmer’s center of gravity, trunk inclination angle, and projected frontal area during front crawl swimming. Six swimmers performed front crawl swimming with sustained maximal (MAX) and minimal (MIN) lung volumes at same submaximal velocity. An underwater motion capture system was used to collect 3D motion data of each body segment during swimming. The whole-body surface was scanned for each subject on dryland with MAX and MIN and the quantified surface data were fitted to the 3D motion data of swimming. The center of gravity position was lower in MIN condition. The trunk inclination angle and projected frontal area were larger in MIN condition. These results suggest that smaller lung volume during front crawl swimming induces larger projected frontal area owing, in part, to the lowered center of gravity and the increase in trunk inclination angle.