Table 1.

VIST exercise descriptions.

Name of exercise	Description of requirement for level zero (most basic, training and testing level)
Smooth Pursuits	A small object was presented that moved on an invisible spline, in an unpredictable manner, across the visual field, near and far from the eyes. Participants were to follow the object with their eyes (head still) and concurrently trace the path with a collider on a hand controller. Points were achieved according to ability to keep the collider in contact with the object.
Saccades	A small object was presented which rapidly and unexpectedly moved, in an unpredictable manner, across the visual field, near and far from the eyes. With the head still, participants were required to use a saccadic eye movement to locate the new position of the object and select it with a manual pointer on a hand controller. Points were achieved according to the number of selections (hits).
Near Point Convergence	A small object was presented which moved close and far from the eyes in the virtual environment. Participants were required follow the path of the object with their eyes and use the manual controller to align a second object with the first object as it moved. Points were achieved according to time the second object was in contact with the first object.
Peripheral Vision	A small colored object was presented in the center of the screen while four colored blocks on the left and right side of the screen were also presented. All the objects changed color each time a selection was made. Participants were to look at the central object, use their peripheral vision to identify the block with the same color, and select that block with the manual pointer on the hand controller. Points were achieved according to the number of correct selections (hits).
Visual Figure	A specific object was hidden in a visually complex environment. Participants utilized visual scanning to locate the object and then select it with a manual pointer on a hand controller. Each selection resulted in a shuffling of the environment and a new location of the hidden object. Points were achieved for each selection of the hidden object within the timeframe.
Joint Position Target	A bulls-eye target was presented centrally in the visual field. A pointer from the center of the headset enabled the participant to align their head with the center of the target. The participant was instructed to look right, left, or up to cause the screen to go black. Then the participant was instructed to return their head to the beginning location (using cervical proprioception without visual input). Once returned to midline, a manual trigger was depressed, revealing how close to the original location they were. Points were achieved based upon overall error in repositioning from center. Three repetitions were completed in each direction (this was not timed).
Neuromotor Maze	A complex map was presented in the IVR headset. A small object, which was controlled by the position of the participant's head, was presented. The participants were required to navigate the object through the map as accurately and fast as possible (using cervical neuromotor control). Errors off the map produced a negative sound. Points were accumulated as they made it through the map on the ascribed path (speed and accuracy).
Cervical Posture	The exercise required participants to move between a neutral head position and a proper cervical retraction with a 3 s hold. Points were accumulated by achieving correct cranial-cervical flexion and return to neutral.
Balance	A visually tilting environment was presented to the participants, which slowly changed between a left and right horizontal tilt. Participants were required to maintain postural stability in standing, minimizing sway. Score was based upon the amount of postural sway.