Aquatic High-Intensity Interval Training for Parkinson's Disease

Inclusion Criteria: * PD stages 2-3 based on Hoehn and Yahr classification system * Balance difficulty (BBS score \<45) * Reduced motor function * Sarcopenia (per EWGSOP2 criteria) * Age ≥ 55 * Permission from their doctors to participate * Absence of a history of myocardial infarction within the past 3 months * Capacity to provide informed consent to participate in the study Exclusion Criteria: * Cardiac instability (angina, decompensated congestive heart failure, severe arteriovenous stenosis, uncontrolled arrhythmias, etc.) * Active infection or acute medical illness * Hemodynamic instability * Labile glycemic control * Inability to exercise (e.g. lower extremity amputation with no prosthesis) * Severe musculoskeletal pain at rest or with minimal activity * Inability to sit, stand or walk unassisted (walking device such as cane or walker allowed) * Shortness of breath at rest or with activities of daily living