Effects of 12-week inspiratory muscle training with low resistance in patients with multiple sclerosis: A non-randomised, double-blind, controlled trial

Background: Patients with multiple sclerosis (MS) have respiratory limitations like fatigue or muscle weakness. The aim of the study was to evaluate the effectiveness of a low-intensity protocol with inspiratory muscle training (IMT) to improve respiratory strength, spirometric parameters and dyspnea in patients with MS. Methods: This study was a controlled, non-randomised, double-blind trial on 67 patients with MS distributed in 2 groups, intervention group (IG) (n = 36) and respiratory exercise group (REG) (n = 31). Over 12 weeks, 5 days/ week, 15 min/day all subjects followed a respiratory training program. IG trained with IMT with low resistance (20% maximum inspiratory pressure (MIP) during the first two weeks, 30% MIP after the second week). REG followed a program involving nasal breathing and maximum exhalation. Main outcome measured was inspiratory strength (MIP); secondary outcomes were maximum expiratory pressure (MEP), spirometry, dyspnea and health-related quality of life. Results: After respiratory training, the intervention group improved MIP, MEP, MVV, peak expiratory flow (PEF), tidal volume (TV) and dyspnea, 51%, 36%, 21%,11%, 51% and 19% respectively (p < .001, p < .001, p < .001, p < .05, p < .05, p < .05). The control group improved MIP, MEP, MVV and PEF, 24%, 27%, 28% and 12% respectively (p < .001, p < .001, p < .001, p < .05). Improvements achieved on MIP and dyspnea were significantly higher in IG patients (p=.002, p=.046, respectively). Conclusion: 12-week inspiratory muscle training with low resistance was more effective than conventional respiratory exercises to improve respiratory strength, spirometric parameters and dyspnea in patients with multiple sclerosis.