UBC Theses and Dissertations
Does interlimb transfer of locomotor adaptations depend on limb dominance? Crombeen, Matthew
Generalization of these adaptations have been found to occur across task, workspace and between limbs. Interlimb adaptation transfer appears to depend on limb dominance. Transfer of adaptation from the non-dominant to the dominant limb involves faster rate of adaptation in movement trajectory patterns, while transfer from the dominant limb to the non-dominant limb involves a faster rate of adaptation positioning related parameters of movement. Although such observations are robust for upper limb adaptations, the extent of interlimb transfer during locomotor tasks is still unclear. The objective of this study was to determine whether locomotor adaptations to a velocity-dependent resistance transfers asymmetrically depending on dominance associated with the legs. It was expected that transfer of adaptation will occur according to dominance, with the dominant limb showing faster adaptation in terms of foot trajectory following non-dominant limb learning; and the non-dominant limb showing faster adaptation in terms of heel strike position following dominant limb learning. Twenty able-bodied adults who were right hand and right leg dominant walked unipedally in the Lokomat robotic gait orthosis, which applied a velocity-dependent resistance against leg movements. The resistance was scaled to 10% of the individual’s maximum voluntary contraction of the hip and knee flexors. Subjects performed a heel targeting task that was scaled to their individual step length. Subjects were then randomly assigned to either the RL training group, testing transfer to the non-dominant limb, or to the LR training group, testing transfer to the dominant limb. Muscle activity (surface electromyography) and joint kinematics were recorded from the lower limbs. The adaptation rate in the initial foot trajectory slope and end point error were compared between the groups and across trials using a 2 by 3 repeated measures ANOVA. There was no difference between the groups for either initial foot trajectory slope (p = 0.106) or end point error (p = 0.763). There was also no evidence for transfer of motor adaptations between the lower limbs in the other gait variables. These results suggest that interlimb transfer of locomotor adaptations is limited, but further studies are warranted to understand the neuromechanical mechanisms controlling locomotor adaptations.
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