Strength and isometric torque control in individuals with Parkinson's disease

It has been previously reported that patients with Parkinson's disease (PD) struggle with fine adjustments of finger forces while manipulating an object. However, impairments in everyday activities can not only be attributed to difficulties with the linear forces applied on an object, but also to the application of rotational forces (torque). This study examined finger strength and isometric torque control in elderly persons with PD. Six individuals with PD (66.1 +/- 0.7 years), six elderly healthy controls (65.3 +/- 0.2 years) matched by age, gender and handedness, and six young adults (22.3 +/- 0.2 years) participated in this study. The subjects were asked to perform two tasks: maximum voluntary thumb-index pinching torque production (MVT) and constant isometric thumb-index torque control at 40% of their MVT for 20 s. The results showed decreased strength and increased difficulty in isometric torque control in individuals with PD as compared to their healthy peers. This study demonstrates that PD affects isometric finger torque production and control.