Adaptation of Automatic Postural Responses in the Dominant and Non-dominant Lower Limbs

For posture control, in healthy people there is an integration between lower limbs. The dominant lower limb for stabilized tasks may have an advantage in adapting automatic postural responses (APR), compared to the non-dominant lower limb. In this investigation, we aim to identify the adaptation process in the magnitude of activation of the medial (MG) and lateral (LG) gastrocnemius muscles in the dominant and non-dominant lower limbs for stabilizing tasks in repeated postural perturbation. Postural responses to repeated perturbations were assessed in the dominant and non-dominant lower limb (defined by the Waterloo Footedness Inventory adapted questionnaire) of 23 healthy young people. Postural perturbations were induced by unexpectedly releasing a load that corresponded to 8% of the participant's body weight. The results of the study show (a) adaptation in the LG muscle, with a reduction in the magnitude of muscle activation between attempts on both legs, and (b) less activation of the MG muscle in the dominant leg when compared to the non-dominant leg. In conclusion, our results indicate that the magnitude of activation of MG and LG, between the lower limbs is asymmetric in response to unanticipated upright postural perturbations. However, the adaptation of the activation magnitude is similar between the lower limbs.