Feedforward postural control in individuals with multiple sclerosis during load release.

The aim of the present study was to investigate the organization of anticipatory postural adjustments (APAs) in individuals with multiple sclerosis (MS) during self-initiated perturbation in the sagittal plane. Eleven individuals with MS and eleven age-and-gender matched healthy controls were asked to hold a 2.27 kg load in the extended arms and release it using fast arm abduction movements. Electrical activity of six leg and trunk muscles as well as displacements of the center of pressure (COP) were recorded. The results indicate that individuals with MS (1) demonstrate a reduced magnitude of APAs, (2) delayed latency of APAs and (3) smaller anticipatory COP displacement as compared to healthy control subjects. Moreover, in spite of individuals with MS being mildly affected, their balance capacity was significantly diminished. Thus, the outcome of this study demonstrates the underlying impairment in anticipatory postural control of individuals with MS and provides a background for development of rehabilitation strategies focused on balance restoration in this population.