Background: Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor symptoms such as resting tremor, freezing episodes, gait disturbances, rigidity, and bradykinesia. It is estimated that approximately 6.1 million people worldwide live with PD. With disease progression, freezing episodes and gait impairments intensify, significantly limiting independence and increasing both fall risk and mortality. Although a definitive cure is lacking, symptom management relies on pharmacological and non-pharmacological interventions.

In PD patients, adaptability to environmental changes and the ability to process sensory inputs and generate motor responses become impaired. Therefore, sensory re-education using auditory, somatosensory, or visual cues is employed. External cues support motor learning by facilitating initiation and maintenance of movement. By promoting cortical reorganization, these cues can improve gait quality, reduce freezing severity, and enhance participation in daily life.

A commonly used method in this context is Rhythmic Auditory Stimulation (RAS). Administered with metronome beats or music, RAS provides external cues via the auditory system to reorganize gait patterns. In patients experiencing freezing, motor blocks during gait can be overcome through rhythmic stimulation. Numerous studies have reported that RAS improves gait speed, step length, and cadence.

Despite its benefits, there is a paucity of methodologically robust, standardized trials evaluating the effects of RAS on real-world symptoms such as gait disturbances and freezing. Therefore, there is a clear need for structured interventions based on metronome-driven rhythmic cues and clinical trials assessing their impact. Furthermore, investigating feasibility in home settings via telerehabilitation is valuable for enhancing accessibility of such interventions.

Purpose: To assess the effects of a structured rhythmic exercise program using metronome cues on freezing episodes, gait parameters, balance, fall risk, and quality of life in PD patients.

Methods: This randomized controlled trial is planned at Taksim Training and Research Hospital from May 2025 to May 2026. Ethical approval has been granted by Istanbul Medipol University's Non-Interventional Clinical Research Ethics Committee (No. E-10840098-202.3.02-221). Sample size was determined via G*Power analysis: two groups (n=13 each), total n=26. Participants will be randomized using Random.org into the Rhythmic Exercise Group (REG) or the Exercise Group (EG).

Both groups will receive a supervised home-based exercise program, overseen via telerehabilitation. Exercises will be performed 3 times per week for 45-60 minutes each session, over 4 weeks (12 sessions total). Progression to the next week's program will require an 80% success rate; otherwise, the same week's program will be repeated. Online supervision will monitor weekly performance.

REG: The structured exercise program will be conducted with metronome cues tailored to each participant's cadence using the "Google Metronome" app.

EG: Participants will perform the same exercises at their own pace, without rhythmic cues.

At the first visit, the demographic information form containing the demographic information and clinical features of all volunteers will be recorded with the necessary information. Then; The participants' disease severity and disability levels will be assessed with the Unified Parkinson's Disease Rating Scale (UPDRS); Walking parameters such as walking speed, step length, step count, cadence and freezing times during walking will be assessed with the 10-Meter Walk Test (10MYT) using Movemate Version 1; Balance skills will be assessed with the MiniBESTest; Performance, with the Timed Up and Go Test (TUG); Freezing and falls in ADL will be assessed with the Freezing While Walking Scale (WGS) and; Falls, with the International Falls Efficacy Scale (IFES); Quality of life will be assessed with the Parkinson's Disease Quality of Life Questionnaire (PHA-39). The assessment tests will be administered face-to-face at the beginning of the study and at the end of the 4th week, 12-18 hours after taking the medication.

Inclusion Criteria:

• Hoehn and Yahr Scale Stage III-IV
• Mini Mental Test Score > 24
• Stable medication use for the last month
• Age range 55-75
• Able to walk 20 meters independently on level ground
• Answering Yes to the first question of the New Freezing of Gait Questionnaire
• Having a caregiver with you during the exercises

Exclusion Criteria:

• Neurological and Orthopedic Disorders Other Than PD
• Medically diagnosed hearing loss
• Patients requiring assistive devices for ambulation
• Dementia
• No internet access via smartphone or computer
• Patients with deep brain pacemakers
• Having vascular lower extremity pathologies
• Not receiving any additional physical therapy during the study period