Inspiratory Muscle Training Improves Fitness and Dyspnea in Obese Women: Randomized Controlled Trial

Background: and Purpose: Women living with obesity have increased work of breathing due to adiposity on the chest wall and higher metabolic demands. Consequently, dyspnea is a major deterrent to physical activity. This study aimed to determine the effects of inspiratory muscle training (IMT) compared with usual care on respiratory muscle function, physical fitness, and dyspnea. Methods: Thirty women were randomly assigned to IMT (IMTG) or usual care (control group [CG]). IMT consisted of 2 sets of 30 inspiratory efforts at 55% of maximum inspiratory pressure (MIP), adjusted weekly, 5 days a week for 4 weeks. IMT was home-based and supervised. CG did not receive any IMT or intervention. The primary outcomes were MIP, sustained maximum inspiratory pressure (SMIP), distance walked in the Incremental Shuttle Walking Test, and dyspnea intensity. Secondary outcomes included maximum expiratory pressure, predicted peak oxygen consumption (VO 2 peak ), the thirty-second Sit-to-Stand test (STS), and rating of perceived exertion. Outcomes were measured at baseline and after 4 weeks. Results: IMTG improved MIP ( P = .01), SMIP ( P = .01), distance walked ( P = .03), predicted VO 2 peak ( P = .01), STS ( P = .01), and decreased Borg dyspnea ( P = .03), whereas these outcomes did not change in the CG. Discussion: Improvements in respiratory muscle strength and endurance likely contributed to the enhanced physical fitness and reduced dyspnea, suggesting a potential pathway for IMT to positively affect exercise capacity and well-being. Conclusions: IMT increased strength and endurance of the respiratory muscles, physical fitness, and decreased dyspnea in women living with obesity.