Brief Title: Aerobic Training on Cerebrovascular Function, Cognition and Gait in Parkinson's Disease

Effects of Aerobic Training on Cerebrovascular Function, Cognitive Performance and Gait Parameters in Patients With Parkinson's Disease: A Randomized Controlled Trial

This randomized controlled trial will investigate the effects of a 12-week supervised aerobic training program on cerebrovascular function, peripheral vascular health, cardiovascular autonomic modulation, cognition, non-motor symptoms, sleep, mood, gait biomechanics, quality of life, and body composition in patients with Parkinson's disease (Hoehn & Yahr stages 1-3). Participants will be randomly allocated to aerobic training or usual care.

This is a parallel-group randomized controlled trial Participants (n=40) diagnosed with Parkinson's disease, stages 1-3 on Hoehn & Yahr scale, will be randomly allocated (1:1 block randomization) to:

• Aerobic Training Group;
• Control Group (usual care)

The intervention will last 12 weeks, 3 sessions/week Pre and post-intervention assessments will include:

• Cerebrovascular function: neurovascular coupling, cerebrovascular reactivity (breath-holding index), dynamic cerebral autoregulation (transfer function analysis), and acute cerebral blood flow response to exercise (transcranial Doppler; vertebral artery flow during silent reading).
• Peripheral vascular and cardiovascular function: brachial artery flow-mediated dilation, carotid intima-media thickness, resting blood pressure, resting heart rate, cardiorespiratory fitness (VO₂peak), heart rate variability (time and frequency domains), and baroreflex sensitivity.
• Cognitive performance: Montreal Cognitive Assessment (MoCA), Trail Making Test A and B, and Stroop Color-Word Test.
• Gait biomechanics: spatiotemporal parameters, 3D kinematics (Vicon system), and kinetics (force platform).
• Clinical and non-motor symptoms: UPDRS, Non-Motor Symptoms Scale (NMSS), sleep quality (PDSS), anxiety (PAS), depressive symptoms (GDS-15), apathy (Apathy Inventory), fatigue (Parkinson Fatigue Scale), pain (Numeric Rating Scale), and quality of life (PDQ-8).
• Body composition: quadriceps muscle thickness and subcutaneous adipose tissue thickness assessed by ultrasound.

All experimental sessions will be performed in the "on" medication state

Inclusion Criteria:

• Clinical diagnosis of Parkinson's disease
• Hoehn & Yahr stages 1-3
• Stable antiparkinsonian medication for at least 4 weeks
• Montreal Cognitive Assessment (MoCA) score ≥ 18
• Ability to walk independently (with or without assistive device)
• Medical clearance for participation in moderate-intensity exercise

Exclusion Criteria:

• Change in medication
• Contraindication to exercise