Inspiratory muscle fatigue would descend body to a deeper level during maximal 200-m front crawl swimming

The purpose of this study was to test whether the lowering of swimmer’s body observed during 200-m maximal swimming is associated with inspiratory muscle fatigue. Ten well-trained swimmers performed maximal 200-m front crawl swimming in 25-m pool. A 3-D underwater motion capture system was used for data collection and the vertical position of the mid-point between xiphoid process (XP) and greater trochanter (GT) was measured at 0–25 m and 150–175 m sections to determine the difference between the sections. Maximal inspiratory pressure (MIP) was measured before and immediately after 200-m swimming to evaluate the inspiratory muscle fatigue. Change in MIP between before and after swimming was positively correlated with the difference in body position (r = 0.70, P < 0.05). The result indicates that swimmer’s body was lowered during maximal 200-m front crawl swimming in association with inspiratory muscle fatigue.