UBC Theses and Dissertations
Interlimb transfer of motor adaptations between the legs during walking Houldin, Adina
Adaptations in kinematic and kinetic measurements have been demonstrated to occur in response to dynamic perturbations in the environment via feedback (e.g., reflexes) and feedforward (anticipatory) mediated mechanisms. Generalization of motor adaptations has been found to occur between the limbs, a process called interlimb transfer. Few studies have explored this phenomenon in the lower limbs and none have yet to elucidate whether the response to manipulation of the dynamic properties of one limb during a walking task will transfer to the other limb. This study aimed to determine whether locomotor adaptations to a velocity-dependent force field in one (trained) leg will transfer to the contralateral (test) leg during unipedal walking. It is expected that neuromuscular adaptations to force perturbations in the trained leg during walking will transfer to the contralateral test leg via generalization of anticipatory adaptive strategies. Twenty able-bodied, right leg dominant, adults walked unipedally in the Lokomat robotic gait orthosis, which applied velocity-dependent resistance to the legs. The amount of resistance was scaled to 10% percent of each individual’s maximum voluntary contraction of the hip flexors. Electromyography and kinematics of the lower limb were recorded. All subjects were tested for transfer of motor adaptations from the right leg to the left leg. Catch trials, consisting of the unexpected removal of resistance, were presented after the first step with resistance and after a period of adaptation to determine if there were any after-effects. The time course of adaptation in hip kinematics showed no significant differences between the legs. Catch trials of the lower limb kinematics were compared within and between the legs using a 2 by 2 repeated measures ANOVA. There was a main effect for time (p < 0.001) and an interaction effect for time and leg (p = 0.011). Post-hoc tests reveal no differences in the size of the after-effects between the legs during the catch trials. Motor adaptations to resistance against right unipedal walking did not generalize to left unipedal walking. The results of this study will add to our current understanding of the neural mechanisms that drive the basic walking pattern.
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