Compensatory control between the legs in automatic postural responses to stance perturbations under single-leg fatigue

Does footedness affect bilateral plantar flexor responses to sudden stance perturbations under unilateral lower leg muscular fatigue?

“…Participants provided informed consent, according with the experimental procedures approved by the Research Ethics Committee of the University of São Paulo (São Paulo, Brazil, approval reference number 3.047.974), in conformity with the ethical standards laid down by the Declaration of Helsinki. This work is a secondary analysis of a previous published study 17 , that explored between-leg asymmetry in the production of automatic postural responses to a sudden balance perturbation.…”

“…Intertrial intervals were about 15 s, with the whole series of perturbations lasting approximately 3 min. Anticipation of load release was prevented by means of variable intervals of 2-5 s between the verbal prompt and perturbation onset (see Rinaldin et al 17 for a detailed description).…”

“…These findings support the assumption that interpedal balance asymmetries can be detected in conditions in which the two legs interact asymmetrically for maintenance of balance stability. In this regard, Rinaldin et al 17 developed a unipedal fatigue protocol for analysis of reactive postural responses that is able to produce a context of asymmetric muscular activation between the fatigued and non-fatigued legs, given that muscular fatigue characterized by a decreased maximal capacity to generate force or power output 18 . Rinaldin's results showed compensation for the weaker response magnitude of the fatigued leg by an increased response magnitude of the non-fatigued leg.…”

Vigor of reactive postural responses is set from feedback and feedforward processes

“…In situations that one individual's leg is disabled like in unilateral stroke, the unimpaired leg compensates for the weak responses of the impaired leg in automatic postural reactions to extrinsic stance perturbations (Coelho, Fernandes, Martinelli, & Teixeira, 2019). To study compensatory control between the legs, we recently performed an experiment evaluating reactive lower leg muscular responses to unanticipated forward stance perturbations in the condition that the plantiflexor muscles of one leg only were fatigued (Rinaldin et al, 2021). Results revealed that a low muscular activation of the fatigued leg when responding to stance perturbations was compensated for by stronger muscular activation of the non-fatigued leg in comparison with the pre-fatigue state.…”