GAIT INITIATION IN HEALTHY YOUNG and HEALTHY OLDER ADULTS and IN ADULTS WITH PARKINSON'S DISEASE.

Abstract

Purpose/Hypothesis: Gait initiation refers to the transition from standing motionless to taking a step forward and reaching a constant walking speed. Gait initiation is often problematic in persons with Parkinson's disease due to akinesia and bradykinesia. The purposes of this study were to describe gait initiation kinetics, specifically center of pressure (COP) excursion patterns, and to determine if COP varies when gait is initiated with the right or left foot, slow or fast speeds and between healthy young (HY) and healthy older (HO) adults and adults with Parkinson's Disease (PD). Number of Subjects: Fourteen subjects, five HY (ages 21–27), five HO (ages 50–60) and four persons with PD (ages 75–85 with Hoehn and Yahr scores of I-III) initiated gait upon seeing a light-emitting diode signal and walked forward approximately four meters. Materials/Methods: Six trials were performed for each condition (step with right or left foot first, self-determined slow or fast speed) for a total of 24 trials. COP was obtained using a Kistler force plate and spatial and temporal parameters were determined by a Labview data analysis program designed by the first author. Initially, a 3 (HY, HO, PD) x 2 (right or left step foot) x 2 (slow or fast speed) ANOVA with repeated measures was used to analyze individual trial data. No differences (p=0.08–0.97) were found when comparing the right and left step foot trials, therefore, right and left trials were pooled for analysis. Then slow and fast speed data were analyzed separately using a one-way ANOVA and Bonferroni post hoc tests using mean data. Results: Subjects with PD tended to be slower than the HY and HO adults as measured by the following temporal variables: reaction time, onset to farthest swing time, farthest swing to forward progression time, and forward progression to end time and were significantly slower for total movement time at slow speeds (p=0.01) and fast speeds (p=0.04). Subjects with PD also had smaller COP excursions than HY and HO adults with respect to the farthest lateral and posterior distance toward the swing limb from the initial COP position and the farthest swing to forward progression distance. There were no differences between the groups in the COP angles for slow (p=0.24) and fast (p=0.16) speeds. Conclusions: Individuals with Parkinson's disease tend to or significantly move slower and have reduced COP spatial excursion patterns as compared to HY and HO adults which may indicate a safety strategy or an unwillingness to produce forces which would move them toward the edges of their base of support and challenge balance during gait initiation. Clinical Relevance: A better understanding of the kinetics during gait initiation in persons with PD will eventually lead to development of more appropriate intervention strategies and hopefully reduce risk of fall.