Biosignal processing methods to explore the effects of side-dominance on patterns of bi- and unilateral standing stability in healthy young adults

Abstract

We examined the effects of side-dominance on the laterality of standing stability using ground reaction force, motion capture (<i>MoCap</i>), and <i>EMG</i> data in healthy young adults. We recruited participants with strong right (<i>n</i> = 15) and left (<i>n</i> = 9) hand and leg dominance (side-dominance). They stood on one or two legs on a pair of synchronized force platforms for 50 s with 60 s rest between three randomized stance trials. In addition to 23 <i>CoP</i>-related variables, we also computed six <i>MoCap</i> variables representing each lower-limb joint motion time series. Moreover, 39 time- and frequency-domain features of <i>EMG</i> data from five muscles in three muscle groups were analyzed. Data from the multitude of biosignals converged and revealed concordant patterns: no differences occurred between left- and right-side dominant participants in kinetic, kinematic, or <i>EMG</i> outcomes during bipedal stance. Regarding single leg stance, larger knee but lower ankle joint kinematic values appeared in left vs right-sided participants during non-dominant stance. Left-vs right-sided participants also had lower medial gastrocnemius <i>EMG</i> activation during non-dominant stance. While right-side dominant participants always produced larger values for kinematic data of ankle joint and medial gastrocnemius <i>EMG</i> activation during non-dominant vs dominant unilateral stance, this pattern was the opposite for left-sided participants, showing larger values when standing on their dominant vs non-dominant leg, i.e., participants had a more stable balance when standing on their right leg. Our results suggest that side-dominance affects biomechanical and neuromuscular control strategies during unilateral standing.