Abstract

This study aimed to clarify the effect of body position on cough force and respiratory function. Twenty healthy young males were included. Cough force and respiratory function were measured using a spirometer in the sitting, side-lying, 30° head-up, and supine positions. The order of measurement for each body position was randomized. Peak cough flow was used as an index of coughing force. Peak cough flow, vital capacity, % vital capacity, tidal volume, forced expiratory volume1.0%, forced expiratory volume in one second and forced vital capacity showed no significant differences between body positions. However, inspiratory capacity was significantly lower and expiratory reserve volume was significantly higher in the sitting and side-lying positions than in the 30° head-up and supine positions. Peak cough flow was significantly positively correlated with vital capacity and forced expiratory volume1.0%, forced expiratory volume in one second and forced vital capacity. The conflicting relationship between inspiratory and expiratory volumes may have resulted in PCF showed no significant difference between four body positions.