DECREASED ARM SWING AT FAST WALKING SPEED IN MILD PARKINSON DISEASE (PD).

Abstract

Purpose/Hypothesis: Clinicians commonly note that people with mild PD have reduced arm swing but the relationship to walking speed remains unknown. The purpose of this study was to determine whether arm swing was reduced at various walking speeds compared to controls. We hypothesized that PD subjects would 1) have a narrower range of gait speeds compared to controls and 2) demonstrate less arm swing than controls. Number of Subjects: We tested 10 subjects with mild PD (stages 1–3) and 10 healthy age and gender matched control subjects. Materials/Methods: Subjects walked across a 10 m room at three different speeds: slow, natural, and fast. For the slow and fast conditions, the subjects were instructed to walk as slow or as fast as they could. For the natural walking condition, the subjects were told to walk at their normal and comfortable walking speed. Three trials in each condition were recorded using a Vicon system. The order of the conditions was randomized for each subject. Gait speeds and shoulder angles in the sagittal plane, as a measure of arm swing, were calculated for two strides per trial. For the PD group, we looked at the more impaired arm and for the control group, we analyzed their dominant side. At matched speeds, Mann-Whitney Rank Sum Tests were used to compare peak-to-peak shoulder angles per stride between the two groups. A Pearson Product Moment r was calculated between gait speeds and peak-to-peak shoulder angles for both groups. Results: There was no difference in the mean speeds for the three different conditions between the two groups. Both groups increased arm swing with an increase in gait velocity (r =.71 for PD group, r =.79 for control group). The PD group demonstrated significantly smaller amplitudes of arm swing in the fast walking condition (p=.045) compared to the control group. There were no differences in arm swing between the two groups in the slow or the natural walking conditions (p=.212, p=.089). Conclusions: The PD group was able to regulate gait speed across the same range as the control group. However, decreased arm swing was noted in patients with mild PD only in the fast condition, when they were walking at a faster than normal speed. Clinical Relevance: Clinicians should be cautious to take gait speed into account when assessing arm swing. Previous work has shown that with verbal instructions to increase arm swing, patients with PD not only increased arm swing but also walked faster than natural walking speed. Instructing more advanced PD patients, whose fast walking speeds are below the level of functional ambulation, to increase arm swing while walking fast may increase walking speed and improve function, but this remains to be proven.