EFFECTS OF POSTURE ON THE COORDINATION OF RESPIRATION AND SWALLOWING

1. Although a pause in respiration during swallowing is a feature comm on to all mammals, inhibition usually occurs during expiration in adul t humans and during inspiration in most other species. We tested the h ypothesis that this difference is due, at least in part, to the positi on of the body while feeding. 2. The coordination of respiration and s wallowing was studied in adult human subjects in two body positions: u pright, which is typically human, and on hands and knees, which is sim ilar to the feeding posture of most other animal species. 3. Our major finding was that the respiratory phase in which swallowing occurred w as significantly related to posture. Swallows tended to occur late in the expiratory phase while feeding upright, but during early expiratio n while on all fours. 4. We speculate that the phase of respiration in which swallowing occurs changes with posture to compensate for the al terations in the mechanical properties of the upper body.