The Transition from Standing to Walking Is Affected in People with Parkinson's Disease and Freezing of Gait

Background: It has been hypothesized that freezing of gait (FOG) in people with Parkinson's disease (PD) is due to abnormal coupling between posture and gait. Objective: In this study, we examined the relationship between anticipatory postural adjustments (APAs) preceding gait initiation and the kinematics of the first two steps between people with FOG and without FOG. Methods: The kinetics and kinematics of self-initiated gait were recorded in 25 people with PD (11 with FOG, 14 without FOG). Outcome variables included the amplitude and timing of the ground reaction forces (GRFs), center of pressure (CoP) shifts and the spatial and temporal characteristics of the first and second steps. Results: The magnitude and timing of the APA phase of gait initiation were not significantly different between participants with and without FOG, yet the first step in the FOG group was distinguished by a significantly wider and less variable first step width, followed by a subsequent wider and shortened second step with reduced toe clearance. Multiple linear regression showed that the relationship between the initial conditions (stance width), APAs (posterior shift of the CoP) and the kinematics of the first step were different between groups with a significantly increased slope in the FOG group. Conclusion: These findings demonstrate that the transition from standing to walking is different between those with and without FOG and that alterations in the initial conditions or APAs are more likely to impact the execution of the two steps in people with FOG.