Postural responses of young adults to collision in virtual world combined with horizontal translation of haptic floor.

Balance and postural response strategies change when subjects are exposed to horizontal translations of the floor or virtual reality or both. This may impact the balance training strategy and balance capabilities assessment in the future telerehabilitation. In the study 15 neurologically intact volunteers participated. Balance standing frame with virtual reality tasks and our novel haptic floor able to generate horizontal translations were used. The postural responses were measured with center of gravity and muscle electromyography of plantar-dorsiflexors, quadriceps, hamstrings, hip and spine muscles in three scenarios. The results demonstrated that center of gravity and electromyographic activity were comparable; with low latency at translation only, longer latency at combination with virtual reality and long latency when only virtual reality was applied. Soleus and semimembranousis demonstrated lower latency at back-right horizontal translations when virtual reality was present. The outcomes suggests that the postural strategy changes from ankle to ankle-hip strategy with availability of additional sensory systems which may be an important issue for objective balance evaluation in the clinical environment and remote telerehabilitation.