BME Assistant Professor Jason Franz and his research group at the Applied Biomechanics Laboratory recently published “Time-dependent tuning of balance control and aftereffects following optical flow perturbation training in older adults” in The Journal of Neuroengineering and Rehabilitation, the first ranked rehabilitation journal. This paper is an early, proof-of-concept study into the clinical utility of virtual reality as a training tool to enhance waking balance integrity in older adults. According to Dr Franz “We’ve known for quite some time that older adults rely more on vision for balance than otherwise healthy younger people. Our research group uses VR to essentially ‘trick’ the brain into thinking you’re experiencing a fall while walking (through the visual perception of instability). Given older adults’ susceptibility to that virtual instability, which requires task-specific motor adjustments to prevent falling, here we asked whether a similar paradigm be used to increase balance confidence and promote reactive balance control in walking.”

So far, thirteen older adults participated in a randomized, crossover design performed on different days that included 10 min of treadmill walking with (experimental session) and without (control session) optical flow perturbations. They used electromyographic recordings of leg muscle activity and 3D motion capture to quantify foot placement kinematics, lateral margin of stability, and antagonist coactivation during normal walking (baseline), early (min 1) and late (min 10) responses to perturbations, and aftereffects immediately following perturbation cessation (post). Despite continued perturbations, most outcomes returned to values observed during normal, unperturbed walking by the end of prolonged exposure. After 10 min of perturbation training and their subsequent cessation, older adults walked with longer and more narrow steps, modest increases in foot placement variability, and roughly half the margins of stability, variability and antagonist lower leg muscle coactivation as they did before training.

The outcomes are very promising, especially with the advent of wearable and low-cost virtual reality technology: the prolonged exposure to optical flow perturbations is useful as a training tool for corrective motor adjustments relevant to walking balance integrity toward reinforcing task-specific, reactive control and/or improving balance confidence in older adults. The full article can be found here.

Fig. 1. Participants walked on a treadmill while watching a speed-matched immersive virtual hallway with and without continuous mediolateral (ML) optical flow perturbations with an amplitude of 0.35 m, applied as detailed in the current methods section