Effects of Inspiratory and Expiratory Muscle Training in Normal Subjects

Abstract

The present study aimed to clarify the effects of inspiratory muscle training (IMT) and expiratory muscle training (EMT) on ventilatory muscle strength, pulmonary function and responses during exercise testing. Young healthy women were randomly assigned to 3 groups: IMT (n=16); EMT (n=16); or untrained normal controls (NC, n=8). Subjects in the IMT and EMT groups trained for 15 minutes twice daily over 2 weeks at loads of 30% maximal inspiratory and expiratory muscle strength, respectively. Ventilatory muscle strength (maximal inspiratory and expiratory muscle strength; PI_max and PE_max, respectively), pulmonary function and progressive exercise testing was performed. Both PI_max and PE_max increased in the IMT group, and PE_max increased in the EMT group. Neither trained group demonstrated any change in pulmonary function or peak values during exercise testing. In the IMT group, exercise-induced increases in heart rate, oxygen uptake (VO₂/kg) and rating of perceived exertion (RPE) decreased with training, as did increases in VO₂/kg and RPE in the EMT group. The increased ventilatory muscle strength in both IMT and EMT groups might improve ventilatory efficacy during exercise, and increased inspiratory muscle strength might facilitate oxygen delivery through improved circulatory responses.