Narrow-based gait in people with Parkinson's disease: Its mechanisms explored

Background People with Parkinson's disease (PD) typically exhibit a narrow-based gait. We previously found that walking with reduced trunk rotation and obliquity led to narrow-based gait in healthy adults; a decrease in trunk motion coincided with a decrease in mediolateral extrapolated center of mass (XCoM) excursion, requiring a smaller step width to maintain a constant mediolateral margin of stability (MoS). Objective To assess whether reduced trunk motion in PD is related to narrow-based gait, without affecting mediolateral MoS. To explore the underlying mechanisms of narrow-based gait, we examined the effects of increasing arm swing (aiming to increase trunk motion), and widening steps on gait in PD. Methods Fifteen people with PD and narrow-based gait and 17 age-matched controls walked on a treadmill for three minutes at a fixed gait speed during three conditions: baseline, increased arm swing and widened step width. Step width, trunk rotation and obliquity were calculated using marker data, and XCoM excursion and MoS using ground reaction forces. Results Trunk rotation, XCoM excursion, and step width were significantly smaller in PD compared to controls, while the MoS did not differ. Increased arm swing did not substantially increase trunk motions in PD, though people with PD were able to widen their step width. Conclusions We provide further evidence for a relation between trunk motion and step width. In PD, reduced trunk motion may contribute to narrow-based gait, without affecting mediolateral MoS; future work is needed to confirm a causal relationship between reduced trunk motion and narrow-based gait in PD.