The influence of position and velocity dependent loads on bimanual coordination

Abstract

<p>Twelve participants performed a bimanual coordination task with the hands in different force field environments. Both in-phase and anti-phase coordination modes were examined. Mean relative phase absolute error measurements represented how accurate the phase relationship was, and the standard deviation of relative phase indicated how stable the coordination mode was. When the fingers were being moved in the same force environments, coordination was more accurate and stable, compared to when the hands were placed in mismatched force environments. Having one hand in a velocity dependent force-field produced less accurate coordination than when one hand was in a position dependent force-field. When coordinated movements were performed with at least one hand in viscous force-field environment, reduced coordination stability was observed, especially during anti-phase movements. There are several spatial, biomechanical and neuromuscular constraints that could have influenced coordination performance. The proposed mechanisms that affected coordination included the differences in neural compensation for different types of force-fields. As shown in previous studies, elastic loads generated later onset of EMG activity whereas viscous loads generated a higher rate of force production. The inability of the extensors muscles to overcome the load resistance in the viscous force-field affected coordination. These results support a two-tiered extension of the HKB model of bimanual coordination.</p>