Abstract

Aim: The study deals with visual feedback control of body position during task-oriented sensorimotor exercise performed under altered stance support conditions in elderly women. Material and methods: Subjects were provided by feedback on COM displacement on a computer screen while standing on stable surface, foam, and spring-supported platform, respectively. Their task was to trace, by shifting COM, a curve flowing either in vertical or horizontal direction. The test consisted of three 30-seconds trials randomly performing in antero-posterior (AP) and medio-lateral (ML) direction. The deviation of instant COP position from the curve was recorded at 100 Hz by means of the system FiTRO Sway Check. The same system was used to register mean distance from the middle of COP while standing on either stable or foam surface with eyes open (EO) and eyes closed (EC), respectively. Results: Results showed that a deprivation of visual control and reduced stance support led to significantly (P ≤ 0.01) higher mean distance from the middle of COP as compared to standing on stable surface with EC. Its values were also significantly (P ≤ 0.05) higher during standing on foam with EO than on stable surface with EO. On the other hand, there were no significant differences in mean COP distance from the curve while performing visually-guided COM tracking task on stable and on foam surface. In addition, mean COP distance from horizontally and vertically flowing curve did not differ significantly while standing on stable (23.6 ± 4.4 mm and 20.8 ± 4.0 mm, respectively) and foam surface (23.5 ± 3.8 mm and 21.2 ± 3.7 mm, respectively). However, its values were significantly (P ≤ 0.01) higher in antero-posterior than in medio-lateral direction (33.2 ± 4.7 mm and 22.2 ± 3.9 mm, respectively) during stance on spring-supported platform. A combination of spring-supported platform and foam showed the same tendency but its values were only slightly higher (35.1 ± 4.7 mm and 23.9 ± 4.6 mm, respectively) than during standing on spring-supported platform. These differences were caused mainly by increasing the COP distance from horizontally flowing curve. Its values were even significantly (P ≤ 0.01) higher as compared to those registered during stance on stable and foam surface. Conclusions: It may be concluded that a) visual feedback control of body position compensates for reduced proprioceptive information during standing on foam surface, and that b) dynamic conditions better differentiate sensorimotor parameters in antero-posterior and medio-lateral direction during visually-guided COM tracking task. Verf.-Referat