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.
Bibliographical noteFunding Information:
This research was funded by the National Institute of Neurological Disorders and Stroke at the National Institutes of Health [Grant numbers R01 NS070264; R01 NS085188 and P50 NS098573]; the University of Minnesota Neuromodulation Innovations (MnDRIVE) and the National Center for Advancing Translational Sciences of the National Institutes of Health [grant number UL1TR000114]. The authors would like to thank the research participants for volunteering their time and considerable effort to advance our understanding of gait initiation in Parkinson’s disease. We also thank Valerie Hatchlowski, Jack Harvey, Krista Keranen, and Hans Zander for their assistance in data collection and processing, and Jacqueline Vachon, and Josh De Kam for their clinical research coordination.
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- Gait initiation
- Parkinson's disease
- anticipatory postural adjustments