The Effects of Whole Body Rotations in the Pitch and Yaw Planes on Postural Stability

Computerized dynamic posturography (CDP) testing will be obtained after practice sessions on all subjects using a CAPS Pro system (Vestibular Technologies, Cheyenne WY, USA). All tests will be conducted with the subject standing on a perturbing foam cushion. Six different conditions will be tested in sequence without the subjects stepping away from the foam/platform in order to assess if the center of sway position changed with the changing test conditions: (1) Eyes Open Head Neutral, (2) Eyes Closed Head Neutral, (3) Eyes Closed Head Right, (4) Eyes Closed Head Left, (5) Eyes Closed Head Flexed, (6) Eyes Closed Head Extended. Subjects will be continuously rotated in a computer-controlled multi-axis chair (Gyrostim by UltraThera Technologies, Inc.) in combinations of whole body Pitch and Yaw simultaneously over a 40 second profile at 90 deg/sec (15 RPM). The acceleration rates to 90 degrees per second as well as deceleration rates will be linear and occur in 1 second. We will utilize rotations that will represent all combinations of pitch and yaw with Pitch direction changing two times and Yaw direction four times (Backward Pitch -20 seconds with right Yaw-10 seconds to left Yaw-10 seconds, to Forward Pitch- 20 seconds with right Yaw-10 seconds to left Yaw 10 seconds). Post rotational CDP testing will be compared to the Pre Rotational CDP,