The Effect of Expiratory Muscle Training on Pulmonary Function in Normal Subjects

Abstract

The objective of the present study was to investigate the effects of expiratory muscle training (EMT) on pulmonary function, including peak cough flow (PCF), by administering EMT at a natural or fast flow rate to healthy volunteers. Subjects comprised 33 healthy volunteers randomly divided into 3 groups: EMT at a natural expiratory flow rate (NFR group); EMT at a fast expiratory flow rate (FFR group); and no EMT (Control group). For the NFR and FFR groups, subjects trained using a device for expiratory muscle training at 30% maximal expiratory muscle pressure (PE_max) for 15 min twice daily, 7 days a week for 4 weeks. Before and after training, PE_max and pulmonary function were measured. For the NFR and FFR groups, PE_max significantly increased but pulmonary function, including PCF, was unchanged. Moreover, no significant correlation was seen between changes in PE_max and changes in pulmonary function parameters in the NFR and FFR groups. In conclusion, natural or fast flow rate EMT increases PE_max, but neither technique improves pulmonary function, including PCF. Thus, velocity-specific muscle strengthening by EMT does not contribute to changes in pulmonary function related to expiratory flow.