| Autor: |
Vitali RV; Department of Mechanical Engineering, University of Iowa, Iowa City, IA 52242, USA.; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA., Barone VJ; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA., Ferris J; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA., Stirling LA; Department of Industrial and Operations Engineering, University of Michigan, Ann Arbor, MI 48109, USA.; Robotics Institute, University of Michigan, Ann Arbor, MI 48109, USA., Sienko KH; Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA. |
| Abstrakt: |
This preliminary investigation studied the effects of concurrent and terminal visual feedback during a standing balance task on ankle co-contraction, which was accomplished via surface electromyography of an agonist-antagonist muscle pair (medial gastrocnemius and tibialis anterior muscles). Two complementary mathematical definitions of co-contraction indices captured changes in ankle muscle recruitment and modulation strategies. Nineteen healthy older adults received both feedback types in a randomized order. Following an analysis of co-contraction index reliability as a function of surface electromyography normalization technique, linear mixed-effects regression analyses revealed participants learned or utilized different ankle co-contraction recruitment (i.e., relative muscle pair activity magnitudes) and modulation (i.e., absolute muscle pair activity magnitudes) strategies depending on feedback type and following the cessation of feedback use. Ankle co-contraction modulation increased when concurrent feedback was used and significantly decreased when concurrent feedback was removed. Ankle co-contraction recruitment and modulation did not significantly change when terminal feedback was used or when it was removed. Neither ankle co-contraction recruitment nor modulation was significantly different when concurrent feedback was used compared to when terminal feedback was used. The changes in ankle co-contraction recruitment and modulation were significantly different when concurrent feedback was removed as compared to when terminal feedback was removed. Finally, this study found a significant interaction between feedback type, removal of feedback, and order of use of feedback type. These results have implications for the design of balance training technologies using visual feedback. |
