The modifiability of triggered stepping reactions, effects of environmental demands

grantor: University of TorontoThe purpose of this thesis was to determine whether perturbation-evoked forward stepping reactions can be modulated to accommodate obstacles, whether such modulation occurs automatically, and which features are modulated. Compensatory stepping reactions were evoked in healthy young adults by unpredictable horizontal movement of a large platform. In the first study, subjects were well able to modulate their forward stepping reactions to clear a high frontal obstacle while recovering balance, even in the earliest trials. A large anticipatory postural adjustment (APA) was used along with a laterally directed step to maintain medio-lateral stability. The second study included a second obstacle condition which constrained lateral foot placement. Subjects then upregulated the APA amplitude in order to guarantee medio-lateral stability. The results provide evidence that triggered stepping reactions can be modulated to deal with environmental constraints, and that large, functional APAs can contribute significantly to balance control during compensatory stepping.M.Sc