Individuals with stroke improve anticipatory postural adjustments after a single session of targeted exercises

Impairment of anticipatory postural adjustments (APAs) is an important source of postural instability in older adults and individuals with neurological disorders. The aim of the study was to investigate whether APAs could be improved in people with stroke as a result of targeted exercise involving their unaffected upper extremity. Nine individuals with stroke and five healthy control individuals participated in the laboratory tests before and after a single session of practice consisting of pushing a medicine ball attached to the ceiling and stopping the ball with their palm when it returns. The tests included self-initiated perturbations induced by fast, discrete shoulder flexion movements and external perturbations induced by a pendulum impact. Bilateral EMG activity of eight trunk and leg muscles was recorded and analyzed during the anticipatory phase of postural control. Significantly early APAs onsets (p < .05) were seen in trunk and leg muscles after a single session of practice as compared to pre-practice in both the groups and individuals with stroke improved their ability to generate APAs more than control group. While the improvement was more pronounced on the unaffected side of the body, enhanced APAs were recorded on the affected side as well. The observed practice-related earlier activations of muscles confirm a possibility of APA enhancement in individuals with stroke. The outcome provides a background for the development of balance rehabilitation protocols focused on improvement of anticipatory postural adjustments in individuals with neurological disorders.