Electrophysiologic changes with incremental exercise in obstructive sleep apnea

Introduction: In patients with obstructive sleep apnea (OSA), intermittent apnea and hypopnea might cause different adaptations in inspiratory and peripheral muscles. In this study we aimed to determine the changes that occur in muscle activation characteristics during incremental exercise testing in patients with severe OSA. Surface electromyography of inspiratory muscles and knee extensors was performed. Methods: Eleven men with severe OSA and 11 matched controls were recruited. Changes in muscle activity were compared by determining root mean square (RMS) and median power frequency (MPF) values obtained at different exercise intensities. Results: The ratios of RMS to oxygen consumption in inspiratory muscles and vastus lateralis increased significantly at peak workload in the control group (P < 0.05), but not in the OSA group. Conclusions: Patients with severe OSA demonstrated an inability to increase motor unit recruitment of inspiratory muscles and knee extensors during incremental exercise.