Slow walking synergies reveal a functional role for arm swing asymmetry in healthy adults: A principal component analysis with relation to mechanical work.

<bold>Introduction: </bold>The purpose of this study was to reveal a functional role for arm-swing asymmetry during gait in healthy adults. To this end, the primary aim was to investigate the role of neuromuscular control on the asymmetry of propulsive and collision joint work at either end of the double-support phase (WDS) in the context of sidedness. The secondary aim was to investigate the effect of neuromuscular control on propulsive and collision joint work at either end of the single-support phase (WSS) in the context of arm-swing asymmetry.<bold>Methods: </bold>Slow -walking trials of 25 participants were analysed using principal component analysis to generate movement synergies (PMk). Independent variables included the tightness of neuromuscular control (N1) formulated from the first PMk and the directional Arm-swing asymmetry index (dASI). Dependent variables included the difference between double-support collision and propulsive joint work (WDS) and a ratio consisting of the difference between single-support collision and propulsive work of both sides (WSS). A linear mixed-effects model was utilized for aim 1 while a multiple linear regression analysis was undertaken for aim 2.<bold>Results: </bold>Healthy adult gait was accompanied by a left-side dominant arm-swing on average. For aim 1, N1 demonstrated a significant negative effect on WDS while sidedness had a negative direct effect and positive indirect effect through N1 on WDS. The most notable finding was the interaction between dASI and N1 which demonstrated a highly significant positive effect on WSS.<bold>Interpretation: </bold>Evidence was put forward that arm-swing asymmetry during gait is related to footedness among healthy adults. Future studies should look to formally confirm this finding. [ABSTRACT FROM AUTHOR]