Overground versus treadmill walking in Parkinson's disease: Relationship between speed and spatiotemporal gait metrics

Background: Treadmills provide a safe and convenient way to study the gait of people with Parkinson's disease (PD), but outcome measures derived from treadmill gait may differ from overground walking. Objective: To investigate how the relationships between gait metrics and walking speed vary between overground and treadmill walking in people with PD and healthy controls. Methods: We compared 29 healthy controls to 27 people with PD in the OFF-medication state. Subjects first walked overground on an instrumented gait walkway, then on an instrumented treadmill at 85%, 100% and 115% of their overground walking speed. Average stride length and cadence were computed for each subject in both overground and treadmill walking. Results: Stride length and cadence both differed between overground and treadmill walking. Regressions of stride length and cadence on gait speed showed a log-log relationship for both overground and treadmill gait in both PD and control groups. The difference between the PD and control groups during overground gait was maintained for treadmill gait, not only when treadmill speed matched overground speed, but also with +/- 15% variation in treadmill speed from that value. Significance: These results show that the impact of PD on stride length and cadence and their relationship to gait speed is preserved in treadmill as compared to overground walking. We conclude that a treadmill protocol is suitable for laboratory use in studies of PD gait therapeutics.

Automated summary

This study investigated the relationships between gait metrics and walking speed during overground and treadmill walking in people with Parkinson's disease and healthy controls. The results showed differences in stride length and cadence between overground and treadmill walking. However, both PD and control groups exhibited a log-log relationship between stride length, cadence, and gait speed in both overground and treadmill walking. The impact of PD on stride length and cadence was preserved in treadmill walking compared to overground walking.