P-NE015. Acute effects of respiratory muscle stretching on ventilatory patterns and respiratory muscle activity

Introduction. Respiratory muscle stretching is useful in reducing chest wall rigidity, consequently increasing chest wall expansion and improving ventilatory patterns. There are few reports that have examined the effects of these techniques in relation to both minute ventilation and inspiratory muscle activities. The purpose of this study was to evaluate the acute effects of respiratory muscle stretching on ventilatory patterns and respiratory muscle activities in healthy persons. Methods. Ten healthy young men participated in the experiment. Subjects were placed in the Fowler’s position. The stretching of both bilateral neck and pectoralis major muscles by a physical therapist was performed throughout the expiratory phase, allowing inspiratory muscles to reach their maximum length during the relaxation time. Two sets of 10 consecutive stretches were performed for each muscle, with a 30 s interval between the series. The ventilatory pattern and inspiratory muscle activities (both sternocleidomastoid and external intercostal muscles) were evaluated through spirometry and electromyography before and immediately after each intervention. Both measurements were taken while the subject breathed at a rate of 30 times per minute. Muscle discharges were quantified using the root mean square to analyze the changes in the contraction levels. The study was performed according to the guidelines set by the Ethics Committee of Aomori University of Health and Welfare. All participants signed an informed consent form. Results. Respiratory muscle stretching promoted a significant acute increase in maximum voluntary ventilation, mean inspiratory flow, and inspiratory muscle activities during tachypnea compared with the control group. Conclusion. Acute effects of respiratory muscle stretching suggested increased respiratory muscle activities and/or improved expansion of ventilatory functions.