Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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In response to sudden postural perturbations, the posture control system uses anticipatory and compensatory postural adjustments (APAs and CPAs) to maintain balance and equilibrium. APAs strengthen as the perturbation magnitude increases, while CPAs remain constant because APAs make the necessary adjustments. However, the magnitude of a postural perturbation cannot always be fully known. ⋯ The lumbar erector spinae (LES) and lumbar multifidus (LMF) activated earlier in the UNKNOWN condition than for the heaviest weight in the KNOWN condition. The outcome of this study indicates that APAs and CPAs of lumbar muscles and displacements of the COP are affected by the knowledge of postural perturbations. The central nervous system (CNS) coped with load perturbations of unknown magnitude with redundancy response strategy, based on the maximum assumption of perturbation magnitude.