Identifying Leading Joint Strategies in a Bimanual Coordination Task: Does Coordination Stability Depend on Leading Joint Strategy?

The authors sought to determine if principles of the Leading Joint Hypothesis, when applied to a multijoint. bimanual coordination task, Could provide insight into the contribution of intralimb dynamics to interlimb coordination. Participants repetitively traced ellipse templates with an isodirectional motion of the end effectors (both hands moving counterclockwise [CCW]) at two cycling frequencies. Ellipse templates were oriented either tilted right or tilted left, yielding a total of 4 left arm-right arm leading joint combinations. Analysis of torque Sign and impulse data indicated that the 4 ellipse-tracing conditions resulted in 4 distinct left arm-right arm leading-joint combinations: 2 conditions with similar leading joints and 2 conditions with different leading joints. Isodirectional CCW ellipse tracing was more stable when produced with similar leading joints compared with when produced with different leading joints. The authors discuss results within the context of intralimb control contribution, to the stability of interlimb coordination patterns.