Do people with Parkinson's disease change strategy during unplanned gait termination?

In light of the movement control problems reported for patients with Parkinson's disease (PD), we examined the lower extremity control strategies used by these subjects to stop walking in planned and unplanned situations. We compared how patients with PD and age and gender-matched control subjects modulated lower extremity muscular activity and ground reaction forces during planned and unplanned stoppings. The main findings were that control subjects did not alter muscle activation from planned to unplanned stopping, relative to stance limb kinetic events; they just increased the amplitude of the response (by approximately 800%). We speculate that these data provide preliminary evidence in support of a stereotypical sequence of muscle activation for gait termination whether planned or unplanned. In contrast, subjects with PD appeared to adopt a different strategy when stopping unexpectedly compared to planned stopping. Additional data show that subjects with PD required additional steps to stop walking when stopping unexpectedly as compared to control subjects.