The purpose of this study was to compare the muscle activation, kinematics, and force production, between Parkinsons patients and healthy, age-matched participants, during sit-to-stand transfers. Twenty-four men (71.5 7.1 years) categorized as Parkinson's patients (N=13), and healthy adults (N=11) participated in this study. The trial protocol required participants to rise from a seated to standing position, from a standard seat height of 17 inches, and return to a sitting position after thirty seconds. Two force platforms, positioned one under each foot, measured antero-posterior and vertical force components as well as peak torque moments during each trial. In addition, muscle activation was measured by a six channel, bi-lateral electromyography (EMG) system and recorded muscle frequency levels at 1000 samples per second (Hz). Reflective markers were placed at lower body joint locations and a kinematic assessment was conducted utilizing a high-speed (Peak Performance Technologies, Inc.) motion analysis system. All data collection devices were synchronized and activated upon initial movement of the subject. A 2 X 2 factorial analysis of variance was used to test for significant differences between groups. Based on the data analysis it was concluded that, although mild to moderately afflicted Parkinsons patients are able to adequately perform sit to stand transfers, the higher levels of ground force application and muscle activation patterns required for this task, compared to their healthy peers, indicates the decreased ability to efficiently apply that force in order to perform this simple daily task.
