Variability in inter-joint coordination during walking of elderly adults and its association with clinical balance measures.

BACKGROUND: Walking requires coordination among multiple joints. Little is known about the association between the coordination ability and fall risks in elderly adults. This study investigated variability of inter-joint coordination in elderly adults and determined its correlation to clinical balance measures.

METHODS: Gait analyses of 15 non-fallers and 15 fallers were performed during walking. Continuous relative phase, derived from phase angles of two adjacent joints, was used to assess the inter-joint coordination. Variability of inter-joint coordination was calculated as the average standard deviation of all points on the ensemble continuous relative phase curve over a gait cycle, namely the deviation phase. Outcomes from three clinical balance tests, including Berg Balance Test, Dynamic Gait Index and Timed Up-and-Go, were examined.

FINDINGS: No significant group differences were detected in hip-knee deviation phase values after accounting for differences in walking speeds. For the knee-ankle deviation phase, fallers demonstrated significantly greater values in the stance phase but smaller values in the swing phase. The hip-knee deviation phase values demonstrated a negative correlation with Dynamic Gait Index, and the knee-ankle deviation phase values had a negative correlation with Dynamic Gait Index and a positive correlation with Timed Up-and-Go time.

INTERPRETATION: Excessive variability of the supporting limb and reduced variability of the swing limb in knee-ankle inter-joint coordination of fallers may contribute to their risk of imbalance or tripping during walking. Compared to Berg Balance Test and Timed Up-and-Go, Dynamic Gait Index scores might be more sensitive to reflect declines in inter-joint coordination during walking.