Effects of inspiratory muscle training on upper and lower extremity functional exercise capacity, muscle oxygen, and cough strength in patients with Parkinson's disease.

BACKGROUND

Respiratory muscle weakness causes inadequate respiration, ineffective coughing, impaired exercise capacity, and autonomic dysfunction. Inspiratory muscle strength training (IMST) may improve these functions; however, its effect in Parkinson's disease (PD) remains unknown.

OBJECTIVE

To investigate the effects of IMST on upper and lower extremity exercise capacity, muscle oxygenation, autonomic function, cough strength, fatigue, and dyspnea in patients with PD.

METHODS

A randomized, controlled, triple-blind study. Twenty patients with PD received IMST at 50% of maximal inspiratory pressure (MIP), and 20 received thoracic expansion exercises (control) for 7 days/8 weeks. The IMST group received one supervised session and six home sessions, while the control group received seven home sessions. Functional exercise capacity (6-minute walk test (6MWT) and 6-minute pegboard and ring test (6PBRT)), muscle oxygenation, autonomic function, cough strength, fatigue (Parkinson's Fatigue Scale (PFS)), and dyspnea (Modified Medical Research Council (MMRC) dyspnea scale) were evaluated.

RESULTS

The 6MWT distance (Cohen's d = 2.02, p = .001), 6PBRT rings (Cohen's d = 1.20, p = .001) resting muscle oxygenation (Cohen's d = 0.81, p = .017), cough strength (Cohen's d = 1.46, p < .001), autonomic function (Cohen's d = 0.63, p = .058), PFS (Cohen's d = 1.20, p = .001), and MMRC (Cohen's d = 1.74, p < .001) scores of the IMST group improved significantly compared to the control. No improvement was prevalent between groups in muscle oxygenation during the 6MWT and 6PBRT (p > .05).

CONCLUSION

IMST improved upper and lower extremity exercise capacity, muscle oxygenation, cough strength, and autonomic function, while lowering fatigue and dyspnea in PD. Improved oxygenation may help patients tolerate higher workloads, aiding endurance and functional gains. These findings support the addition of IMST to rehabilitation programs for improved pulmonary, cardiac, and functional capacity. Increased cough strength may lower the risks of aspiration, pneumonia, and mortality - this requires further investigation. ClinicalTrials number: NCT06017336.