Vertical Posture Maintenance with Multiple Repetitions under the Conditions of Destabilizing Virtual Visual Environment

Аннотация

We studied whether adaptation can occur in healthy subjects under conditions of standing in a three-dimensional virtual visual environment (VVE), which was destabilized, e.g., by introducing the in-phase coupling only between the subject’s body oscillations and the position of visible virtual scene. For approximately 1.5 h, the subjects performed 35 tests lasting 40 s each, standing quietly on a stabilograph, which recorded the oscillations of their body. The interval for rest between the tests was 20–25 s; after every 5 tests, the subjects rested sitting for 4–5 min. The posture maintenance analysis was based on the assessment of the amplitude–frequency characteristics of two elementary variables: the trajectories of the projection of the center of gravity on the support surface (variable CoG) and the difference between the trajectories of the CoP and CoG (variable CoP–CoG). The variables were calculated basing on the trajectories of the center of pressure (CoP) in the anteroposterior and lateral directions. We found that the standing under the conditions of the same type of destabilization of visible visual environment at the end of the tests was significantly improved. The amplitude and frequency characteristics of variables CoG and CoP-CoG was close to those observed in an immobile visual environment. The vertical posture maintenance was improved through changes in both the amplitude and frequency characteristics of variables CoG and CoP–CoG. Thus, we found that multiple repetitions of tests under conditions of virtual visual environment with unstable visible visual environment, resulting in the destabilization of the vertical posture, allowed subjects to effectively adapt and improve the equilibrium characteristics of the body.