The authors investigated anticipatory postural adjustments in persons with unilateral stroke using external perturbations. Nine individuals with stroke and five control subjects participated. The electromyographic activity of 16 leg and trunk muscles was recorded. The onsets of muscle activity during the anticipatory phase of postural control were analyzed. The individuals with stroke did not show an anticipatory activation of leg and trunk muscles on the affected side; instead, the muscle onsets were seen after the perturbation, during the balance restoration phase. However, an anticipatory activation of muscles on the unaffected side was seen in individuals with stroke, and it was observed earlier compared with healthy controls (p < .05). The individuals with stroke showed a distal to proximal order of anticipatory activation of muscles on the unaffected side. The outcome of the study provides a basis for future investigations regarding ways of improving balance control in people with stroke.
Etem Curuk, Yunju Lee and Alexander S. Aruin
Mohan Ganesan, Yun-Ju Lee and Alexander S. Aruin
The use of a footrest while performing activity in standing is frequently associated with improvement of a user’s well-being however no information exists on the role of a footrest in improving postural stability. The aim of the study was to evaluate the effects of using a footrest in postural control. Twenty healthy young volunteers were tested using three experimental conditions: standing with two feet on the force platform and standing on the force platform when one foot was placed on a 15 cm footrest positioned in front or laterally. The mean and root mean square distance, range and velocity of the center of pressure (COP) were calculated in the anterior-posterior (AP) and medio-lateral (ML) directions using the force platform data. The COP displacements in AP and ML directions increased in conditions of standing with one foot placed on the footrest regardless of its location. Standing with eyes closed increased COP displacements further. The outcome of the study suggests the importance of using COP measures for evaluation of postural stability and provides additional information needed for optimization of working conditions involving standing with a footrest.