MS-SAFE: Stepping to Avoid Fall Events in Multiple Sclerosis

Reactive step training sessions will be undertaken in 2 supervised individual sessions over 2 weeks. During each session, a participant will visit Neuroscience Research Australia for 50-minutes of training, focusing on balance recovery from mix of trips and slips (30 trials). A perturbation system built on a 10-m walkway consisting of 50cm x 50cm wooden decking tiles will be used to induce slips and trips (Okubo et al., 2018). Participants walk while being secured with a ceiling-mounted full body harness to avoid falling to the ground. Gait speed during this training will be individually set to approximately 80% (or 50-100% if adjustment is required) of usual speed using a metronome corresponding to individualised cadence. Interspersed with normal walk trials will be a series of trip and slip perturbations with increasing levels of unpredictability and 4 short breaks. A slip is induced by a movable tile on two hidden low-friction rails with linear bearings that result in a slide of 20-70cm upon foot contact. A trip is induced using a 7-14cm height tripping board that springs up from the walkway at mid-swing using a foot detection sensor. Unpredictability of perturbation will be progressively increased so that reactive stepping responses can be gradually and safely trained. Participant performance and anxiety status will be closely monitored and intensity of perturbation (i.e. trip height, slip distance/speed and gait speed) may be adjusted to appropriately progress the challenge and training effects. All training sessions will be conducted individually with an Exercise Physiologist and an assistant.