Lower-limb inter-joint coordination during balance recovery after trips.

Background: Trips are one of the most common external perturbations that can lead to accidental falls. Knowledge about postural control attributes of balance recovery after trips could help reveal the biomechanical causes for trip-induced falls and provide implications for fall prevention interventions.

Research Question: The objective of the present study was to examine coordinated lower-limb movements during balance recovery after trips.

Methods: One hundred and twenty-three volunteers participated in an experimental study. They were tripped unexpectedly by a metal pole when walking on a linear walkway at their self-selected speed. Lower-limb inter-joint coordination quantified by continuous relative phase measures, including the mean of the absolute relative phases (MARP) and the deviation phase (DP), was analyzed during the execution of the first recovery step after unexpected trips.

Results: Compared to unsuccessful balance recovery, smaller MARP and DP of successful recovery were observed with distal inter-joint coordination on the swing side. Inter-joint coordination of the stance limb did not significantly differ between successful and unsuccessful recovery conditions. These findings indicate that the control of the swing limb's distal joints is crucial for regaining balance after trips.

Significance: An implication derived from this study is that greater in-phase coordination and smaller coordination variability in distal joints of the swing limb could be considered as potential targets for interventions aimed at preventing trip-induced accidental.