Investigating Muscle Training's Respiratory Outcomes and Voice Enhancement in Parkinson's Disease

Inspiratory muscle training with two sessions per day, five repetitions per session, six days a week for eight weeks.

Expiratory muscle training with two sessions per day, five repetitions per session, six days a week for eight weeks.

Placebo-controlled expiratory muscle training with two sessions per day, five repetitions per session, six days a week for eight weeks.