Whole-Body Vibration in Parkinson Disease

Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease and affects approximately 10 million people worldwide. Each year, more than 60,000 new cases are diagnosed in the United States alone, and this number is reported to be increasing globally. With the aging population, the prevalence of Parkinson's disease is also rising; in particular, it is reported that the prevalence among individuals over 65 years of age ranges between 1 and 2 per 1,000 people. Therefore, Parkinson's disease represents a significant health and social care burden at both individual and societal levels.

Recent studies emphasize that Parkinson's disease is a multidimensional condition and that the changes occurring during its course play a key role in disease progression.

Balance impairment and postural control deficits are among the most common problems in Parkinson's disease. Research has shown that the risk of falls is significantly increased in this patient group, with approximately 60% of patients exhibiting a tendency to fall. Balance disorders not only threaten physical safety but also restrict individuals' independence and participation in activities of daily living. Therefore, balance is considered one of the primary targets for improvement in Parkinson's rehabilitation.

Gait disturbances are another prominent functional limitation in Parkinson's disease. Reduced walking speed, shortened step length, and irregular gait rhythm lead to significant limitations in daily living activities. Loss of gait performance reduces mobility and makes independent living more difficult. For this reason, gait is considered one of the most critical targets in physiotherapy and rehabilitation programs.

Cognitive impairments are also commonly observed in patients with Parkinson's disease. These impairments typically occur in the domains of attention, executive functions, and memory. Cognitive deficits reduce independence in daily activities, limit social participation, and decrease quality of life. In addition, cognitive impairments may negatively affect the sustainability of gains achieved through motor rehabilitation.

One of the important challenges faced by Parkinson's patients is impaired dual-task performance. In daily life, individuals often need to perform both motor and cognitive tasks simultaneously. However, in Parkinson's disease, significant performance declines are observed in such tasks due to attention deficits, executive dysfunction, and motor control problems. Impairments in dual-task performance represent a critical area where cognitive and motor limitations intersect.

Another important parameter in Parkinson's disease is prolonged reaction time. It is one of the prominent effects of the disease on motor and cognitive functions. Delayed motor responses to sensory stimuli lead to reduced performance in situations requiring quick decision-making and rapid movements in daily life. Prolonged reaction times increase the risk of falls and negatively affect balance and gait performance during dual-task activities. Therefore, reaction time is considered an important functional parameter that should be assessed and improved in Parkinson's rehabilitation programs.

In recent years, Whole Body Vibration (WBV) has attracted attention in studies on non-invasive physical interventions in patients with Parkinson's disease. WBV enhances proprioceptive feedback by stimulating muscle contractions through mechanical vibration, thereby contributing to improvements in motor performance and postural control. This stimulation activates spinal reflexes, supporting rapid and coordinated muscle contractions, and also helps regulate muscle tone and postural control. In addition, WBV increases neuronal activity in cortical motor areas, strengthens neuromuscular coordination, and supports motor learning processes.

Studies have reported that WBV has positive effects on balance, postural control, and gait. However, the literature regarding its effects on cognitive functions and dual task performance remains limited. Most existing studies have been conducted with small sample sizes; there is heterogeneity in intervention protocols in terms of frequency, duration, and number of sessions, and frequencies have not been comparatively examined. Furthermore, there are no studies evaluating cognitive parameters and dual task performance in this context, which limits the generalizability of the findings. These gaps highlight the need for studies investigating the frequency dependent effects of WBV on balance, gait, cognitive functions, and dual-task performance in patients with Parkinson's disease.

The aim of study is to evaluate the effects of different frequencies of WBV on balance, gait, cognitive functions, and dual-task performance in patients with Parkinson's disease.

This study is the first to comparatively examine the frequency-dependent effects of WBV on balance, gait, cognitive functions, and dual-task performance in patients with Parkinson's disease. The findings are expected to contribute to the development of physiotherapy and rehabilitation models tailored to Parkinson's patients, focusing on targeted outcomes and individualized needs by considering the frequency dependent effects of WBV.

Study was designed as a randomized controlled, single-blind trial. In accordance with this aim, all assessments and interventions will be conducted at the Izmir Bakırçay University Physiotherapy and Rehabilitation Practice and Research Center. Patients diagnosed with Parkinson's disease who have been followed up or are currently being followed at the Neurology Department of Çiğli Training and Research Hospital, Izmir Bakırçay University, and who are referred to the Izmir Bakırçay University Physiotherapy and Rehabilitation Practice and Research Center, and who meet the inclusion and exclusion criteria, will be included in the study. Written informed consent will be obtained from all participants prior to enrollment.

In the study, participants' demographic and clinical characteristics, balance, gait, cognitive functions, dual task performance, and reaction time will be assessed using standardized evaluation tools. Demographic and clinical data will be collected using a structured assessment form and will include age, sex, height, weight, body mass index, educational status, marital status, smoking and alcohol use, medical history, and Parkinson's disease related clinical characteristics (Onset Date, Disease Duration, and Disease Stage), as well as Unified Parkinson's Disease Rating Scale (UPDRS) scores and comorbidity information. Comorbidity status will be evaluated using the Charlson Comorbidity Index. Balance will be assessed using the Mini Balance Evaluation Systems Test (Mini-BESTest), while gait performance will be measured using the 10 Meter Walk Test. Cognitive functions will be evaluated using the Verbal Fluency Test, Digit Span Test, Trail Making Test, and Stroop Color and Word Test. Dual-task performance will be assessed using the Dual Task Walking Test and the Dual-Task Timed Up and Go Test, and reaction time will be measured using the Ruler Drop Test. All assessments will be conducted according to standardized protocols, and all data will be recorded systematically.

Participants will be allocated to the intervention and control groups using a stratified randomization method to ensure that the three groups are homogeneous in terms of demographic and clinical characteristics. The intervention group will then be further randomly divided into two subgroups according to the applied frequency levels: Low Frequency (3-10 Hz) and Medium Frequency (12-20 Hz). In both groups, the interventions will be conducted for a total of 8 weeks, two days per week, in a hospital setting under appropriate safety conditions. Participants in the intervention group will perform the same functional exercise based physiotherapy program as the control group, with equal duration and intensity. In addition to the control intervention, the intervention group will receive a 20 minute Whole Body Vibration (WBV) application, which will be integrated at different frequencies (Low or Medium) depending on the assigned subgroup.