Airway protection deficits (cough and swallowing) are prevalent and pervasive in Parkinson's disease (PD), contributing to adverse health outcomes like pneumonia. This study aims to refine cough skill training by examining whether variable versus constant practice conditions improve cough outcomes in people with PD. In addition, this study will provide insight into optimal respiratory adaptations that occur during training to support cough effectiveness, resulting in immediately translatable treatments to improve airway protection-related health outcomes in people with neurodegenerative disease.