Forced-exercise Improves Motor Function In Parkinson's Disease Patients

Abstract

Despite promising results in animal models of Parkinson's disease (PD), human studies describe limited and short-term improvements in motor function following exercise. These discrepancies may be due to differences in exercise rate or modality. The hypothesis underlying this project is that PD patients lack the capacity to exercise at a voluntary rate necessary to alter central nervous system functioning and promote maximal symptom relief. PURPOSE: To determine the effects of voluntary compared to forced-exercise on PD motor function. METHODS: Ten PD patients were randomized to either a voluntary or forcedexercise group. Workload and heart rate was similar between groups, while exercise rate was manipulated. The forced-exercise group cycled on a stationary tandem bicycle for 8 weeks with an able-bodied trainer at a cadence of 80-90 revolutions per minute. Patients were 'forced' to pedal at a cadence greater than their voluntary cadence as their pedals are mechanically linked to those of the trainer. Patients in the voluntary group exercised on a stationary cycle and were not given instructions regarding cadence. Clinical motor function tests were used to assess overall motor function and a bimanual dexterity paradigm was used to assess hand function. RESULTS: Both groups displayed improvements in aerobic fitness. Clinical ratings of motor function showed significant improvement, 35%, for patients in the forced-exercise group compared to no change in the voluntary group. Bimanual dexterity also improved for the forced-exercise group while no change in function was observed for the voluntary group. CONCLUSIONS: These results indicate that increasing exercise rate in PD patients, beyond a self-selected rate, leads to improvements in motor function compared to voluntary exercise. Improved bimanual dexterity following forced-exercise suggests a fundamental shift in the control and coordination of upper extremity actions. Improvements in upper extremity motor function following a lower extremity forced-exercise intervention provide evidence for a change in central nervous system functioning. These findings are consistent with the recent animal literature. Overall, our data indicate that forced-exercise leads to improvements in motor functioning and may be a viable intervention for PD patients.