Effects of high-intensity respiratory muscle training on respiratory muscle strength in individuals with Parkinson’s disease: Protocol of a randomized clinical trial

OBJECTIVE: To investigate the efficacy of high-intensity respiratory muscle training (combined inspiratory and expiratory muscle training) in improving inspiratory and expiratory muscle strength, inspiratory muscle endurance, peak cough flow, dyspnea, fatigue, exercise capacity, and quality of life in this population. METHODS: A randomized controlled trial, concealed allocation, blinded assessments, and intention-to-treat analysis will be carried out. Altogether, 34 individuals with PD (age ≥ 50 years old, with maximum inspiratory pressure (MIP) <80cmH(2)O or maximum expiratory pressure (MEP) <90cmH(2)O) will be recruited. Patients will be randomly assigned to either (1) high-intensity respiratory muscle training (experimental group, 60% of MIP and MEP) or (2) sham training (control group, 0cmH(2)O). Individuals will perform a home-based intervention, with indirect home supervision, consisting of two daily 20-min sessions (morning and afternoon), seven times a week, during eight weeks. Primary outcomes are MIP and MEP. Secondary outcomes are inspiratory muscle endurance, peak cough flow, dyspnea, fatigue, exercise capacity, and quality of life. The effects of the training will be analyzed from the collected data using intention-to-treat. Between-group differences will be measured using a two-way ANOVA with repeated measures (2*3), considering baseline, post-intervention, and 12-week follow-up. IMPACT: The results of this trial will provide valuable new information on the efficacy of high-intensity respiratory muscle training in improving muscle strength, functional outcomes, and quality of life in individuals with PD. Performing combined inspiratory and expiratory muscle training using a single equipment is cheaper and feasible, takes less time and is easy to use. In addition, this intervention will be carried out in the home environment that increases accessibility, reduces time, and costs of transport, which increases the feasibility to reproduce their findings in clinical practice. TRIAL REGISTRATION: NCT05608941. Registered on November 8, 2022.