Patients included in this group will be given additional motor tasks (e.g. passing the ball from the right hand to the left hand while standing on a soft surface, clapping) in accordance with the physiotherapist's commands simultaneously with balance and large amplitude functional activities (such as stepping forward-sideways-backwards, sitting and standing).

Simultaneously with balance and large amplitude functional activities (such as stepping forwards-sideways-backwards, sitting and standing), patients included in this group will be given additional cognitive (e.g. counting while standing with feet closed) and motor (e.g. passing the ball from the right hand to the left hand while standing on a soft surface) tasks in accordance with the physiotherapist's commands.

Kinovea® version 0.8.15 software will be utilized to obtain objective and quantitative data for spatiotemporal parameters of gait (stride length, double stride length, support surface, stride width, cadence, walking speed, step duration) and kinematic parameters of gait. In the study, a 3-meter walking distance of the subjects will be recorded with a camera placed in the sagittal plane. Coloured marks will be placed on the right and left heels, and these marks will be tracked and annotated on the video. The obtained videos will be observed, and the parameters of stride length (the distance between two consecutive heel strikes of one limb and the other limb) and double stride length (the distance between two consecutive heel strikes of the same limb) will be analyzed independently with Kinovea motion analysis software.

The Mini-BEST test, which will be used for dynamic balance assessment, is a 14-item balance scale and evaluates postural reactions, sensory orientation and dynamic walking sub-parameters. In the last part, it allows the assessment of dual-task performance within the scope of the Forced-Reach-Walk Test (with Cognitive Loading). Each item in the test is scored between (0-2); a score of 0 indicates that the person is unable to perform the task, while a score of 2 is normal. The total score will be between 0 and 28. The total score reflects the balance ability. Higher scores mean better balance ability. It is a valid and reliable measurement method that requires approximately 15 minutes to complete, is one-dimensional and valid for use in Parkinson's Disease.

The four-step square test is a clinical assessment used to evaluate the ability to change direction while stepping, particularly focusing on dynamic balance and mobility. During the test, the patient starts in the upper left square (Square 1) and faces Square 2. The step sequence initially moves clockwise: Square 1, then Squares 2, 4, and 3. Subsequently, the sequence reverses, moving anti-clockwise: Square 3, followed by Squares 4, 2, and back to Square 1. The physiotherapist demonstrates the test, allowing the patient to practice and learn the sequence. If the patient cannot complete the sequence successfully, loses balance, or touches a support cane, the test is repeated. Two scores are obtained, and the better of the two scores is recorded. Timing begins when the patient's first foot touches the floor in Square 2 and ends when their second foot touches the floor in Square 1. The shorter the time, the better the result for this test.

KFORCE Plates are a type of force platform utilized to objectively measure postural control parameters. These plates enable the assessment of both static and dynamic balance across a broad spectrum of movements. Consisting of two independent plates, they have the capability to determine weight distribution during the stance phase and calculate the center of gravity. KFORCE Plates evaluate various positions such as standing, single-leg stance, and squatting, providing a comprehensive report with multiple data points post-assessment. This assessment will significantly enhance the project by offering objective data on changes in postural control following exercise interventions and allowing for a more detailed interpretation compared to scale-based assessments.

Parkinson's Activity Scale, a scale developed to evaluate functional activities in Parkinson's Disease, provides information about the transfer status of patients. Scored between 0 and 4 points, a high score indicates good performance. The scale has subdivisions including getting up from a chair, in-bed mobilisation and gait akinesia. In this study, it will be used to evaluate the functional activity status of the patients. High score indicates good functional performance.

The Dual Task Questionnaire consists of 10 questions designed to assess the frequency of difficulties associated with daily tasks involving dual tasking. It is used to measure how often individuals have problems with the content of the questionnaire. In response to the questions, individuals are asked to choose from five options ranging from very often to never or not applicable (5-point scale, using a 0-4 scale). The resulting score is divided by 10 for an average rating per question.