This prospective, randomized, assessor-blinded clinical trial aims to compare the effects of robot-assisted gait training and quadriceps neuromuscular electrical stimulation (NMES) when added to a standard exercise rehabilitation program in patients with Parkinson disease.

Participants will be randomly assigned to two parallel groups. Both groups will receive a standard rehabilitation program, while one group will additionally undergo robot-assisted gait training and the other group will receive quadriceps NMES. The interventions will be administered five days per week for six weeks.

Clinical outcomes, including balance, functional mobility, gait performance, and disease severity, will be evaluated at baseline, post-treatment, and follow-up (week 14). In addition, ultrasound-based assessments of quadriceps muscle thickness and cross-sectional area will be performed to investigate muscle adaptations.

The results of this study are expected to provide comparative evidence regarding the effectiveness of these two rehabilitation approaches and contribute to optimizing rehabilitation strategies in Parkinson disease.

This is a single-center, prospective, randomized, assessor-blinded clinical trial. The study will include patients with idiopathic Parkinson's disease who meet the eligibility criteria. After baseline assessment and written informed consent, participants will be randomly assigned to one of two parallel intervention groups.

All participants will receive a standard Parkinson rehabilitation program including posture exercises, balance and coordination training, stretching and relaxation exercises, functional gait training, and lower extremity strengthening exercises. In addition to this standard program, one group will receive robot-assisted gait training and the other group will receive neuromuscular electrical stimulation applied to the quadriceps muscle.

The intervention period will last six weeks, with treatment sessions performed five days per week. Participants will be evaluated at baseline, at the end of the six-week treatment period, and at follow-up in week 14. Clinical assessments will be performed by an assessor blinded to group allocation. Ultrasonographic measurements of the quadriceps muscle will also be performed using a standardized technique.

The study is designed to compare the clinical and muscle-related effects of these two adjunctive rehabilitation approaches in Parkinson's disease.

Inclusion Criteria:

• Diagnosis of Parkinson's disease according to established clinical criteria
• Age between 40 and 80 years
• Hoehn and Yahr stage II-III
• Ability to walk independently with or without assistive devices
• Stable medical treatment for at least 4 weeks prior to study enrollment
• Ability to understand and follow instructions
• Willingness to participate and provide written informed consent

Exclusion Criteria:

• Severe cognitive impairment or inability to follow instructions
• Hoehn and Yahr stage IV-V Parkinson's disease
• Severe musculoskeletal disorders affecting gait (e.g., advanced osteoarthritis, recent fracture)
• History of lower extremity surgery within the last 6 months
• Severe cardiovascular or respiratory disease limiting exercise participation
• Presence of other neurological disorders affecting mobility (e.g., stroke, multiple sclerosis)
• Contraindications to electrical stimulation (e.g., pacemaker, implanted electronic devices)
• Skin lesions or infections at electrode placement sites
• Participation in another structured rehabilitation program within the last 3 months

Individual participant data (IPD) will not be shared due to ethical and privacy considerations. The study involves sensitive clinical data, and participants have not provided consent for public data sharing.