An anticipatory postural adjustment, but not a crossed unloading reflex, between the hand and foot

Sophisticated interactions between the two hands have been exhibited previously, in which feedforward components aid in postural stabilization of the hands and feedback components aid in coordinated bimanual action, such as grasp. Interactions between hand and foot likewise exhibit feedforward control: there is an anticipatory postural adjustment (APA) in calf muscles that precedes unloading of the foot by the hand. In contrast, interlimb feedback is not evident in the interaction between hand and foot: the authors found no unloading reflex in calf muscles in response to unloading of the hand. Feedforward APA´s may be a general feature of interlimb control, but reflexes between hands may be specialized for bimanual manipulation