Associated movement in hemiplegia: the effects of force exerted, limb usage and inhibitory training

The intensity of associated movement or motor overflow in the contralateral limb during a unimanual task was evaluated in postacute traumatic brain injured (TBI) young adults with left side hemiplegia and age-matched controls. Both groups demonstrated increased overflow with increasing active limb force, although the trend was for greater overflow to occur in the TBI group, particularly when the spastic limb was active. Following three successive days of inhibitory training with electromyographic feedback, TBI subjects were able to significantly reduce the amount of overflow in the contralateral limb, greater inhibition occurring in the noninvolved limb during spastic limb movement. The results are discussed in terms of a dual model of inhibitory control and the role of such processes in uncoupling the limbs for independent limb usage.