Muscle activation and force production in Parkinsonʹs patients during sit to stand transfers

Objective. The purpose of this study was to compare the kinematics, muscle activation, and force production between Parkinsonʹs patients and healthy, age-matched participants during sit-to-stand transfers. Design. This cross-sectional study employed a 2 × 2 × 3 multivariate analysis of variance to test for significant differences between and within groups. Background. The underlying mechanisms that predispose an individual to lose strength during the clinical progression of Parkinsonʹs disease have proved to be elusive, especially during performance of functional tasks such as the sit to stand transfer. Methods. Twenty-four men (mean age: 71.5 years) categorized as Parkinsonʹs patients (n=13) and healthy adults (n=11) participated in this study. Two force platforms measured antero-posterior and vertical force components as well as peak torque. Muscle activation was measured by a six channel, bilateral electromyography system. A lower-body kinematic assessment was conducted utilizing a highspeed motion analysis system. Results. No statistically significant differences were found between groups for the outcome variables measured. However, Parkinsonʹs patients did exhibit significant within-group bilateral differences for the variables of knee angle at seat-off, peak vertical force and peak torque. Conclusion. Data from this study reveal that persons with mild to moderate Parkinsonʹs disease exhibit moderately altered bilateral mechanics when performing a sit to stand transfer compared to their healthy peers.