Dominant or nondominant leg, which one is used to recover balance after a simulated slip during standing?

Background

Standing-slips are used as a fall reduction training modality or fall risk assessment tool. It is unclear whether the trainees prefer one leg over the other to recover their balance after a standing-slip.

Research questions

1) Do the trainees always adopt the dominant leg to recover balance following an unexpected standing-slip perturbation? and 2) What are the determinants for the recovery leg selection?

Methods

Eighty-six participants were exposed to a large-scale slip with varying peak belt speed while standing on a treadmill. Depending on the agreement between the recovery leg and the dominant leg, 54 participants were classified into the congruent group and the other 32 in the conflictive group. The demographic information and peak belt speed were compared between these two groups.

Results

The peak belt speed was significantly different between the two groups (1.47 ± 0.49 m/s for conflictive vs. 1.26 ± 0.37 m/s for congruent, p = 0.026). Individuals tended to use their dominant leg to recover balance after the slip when the peak belt speed was small. The selection of the recovery leg became random when the peak belt speed was increased. The receiver operating characteristics analysis revealed a high accuracy of the peak belt speed in predicting the group classification (the area under the curve = 0.891). The Youden index identified the cutoff value of the peak belt speed (1.2 m/s) that maximized the prediction accuracy.

Significance

The identified threshold of the peak belt speed could provide practical guidance for designing standing-slip-based perturbation training programs for diverse populations.