Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology
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J Electromyogr Kinesiol · Aug 2017
Effects of amplitude and predictability of perturbations to the arm on anticipatory and reactionary muscle responses to maintain balance.
Disturbances to balance arising from forces applied to the upper limb have received relatively little attention compared to disturbances arising from support surface perturbations. In this study we applied fast ramp perturbations to the hand in anterior, posterior, medial and lateral directions. The effects of perturbation predictability and amplitude on the postural response of upper limb, trunk and lower limb muscles were investigated. ⋯ However, the slope of the relation between perturbation amplitude and the magnitude of the change in muscle activation was greater when perturbations were predictable than when they were randomly selected. The timing of both the anticipatory and reactionary increases in muscle activation was invariant across perturbation amplitudes. The characteristics of the reactionary responses have a similar organization to the long latency muscle responses to support surface perturbations.