Acceleration pattern of the upper body during level walking in patients with Parkinson's disease

The aim of this study was to investigate the effects of Parkinson's disease (PD) on upper body acceleration patterns during level walking. Twenty-three patients with PD and 29 controls of similar age participated in this study. Subjects walked along a 12 m linear walkway at self-selected comfortable speeds. Upper body accelerations were measured using three-axis accelerometers located at the pelvis, shoulder, and head. Acceleration magnitude, stride-to-stride irregularity, and degree of coupling among three body parts were derived from the acceleration signals. In the vertical (supero-inferior) direction, PD patients exhibited a smaller acceleration magnitude, a more irregular pattern, and less coupling of acceleration among body parts compared to the controls (p<0.05). In the anterio-posterior (AP) direction, acceleration magnitude at the pelvis in PD patients was smaller than that in the controls (p<0.05). In addition, the phase lag of AP head acceleration from shoulder and pelvis was smaller in PD patients than in the controls (p<0.05). These results suggest that PD patients walk with reduced ankle power generation and a more rigid upper body in the AP direction and with more irregular muscle force generation in the SI direction.