The effect of reactive balance training on responses to novel unexpected balance perturbations: a feasibility study

Trial design: Pilot study embedded within an assessor-blinded parallel randomized controlled trial. Objective: To determine the feasibility of using unexpected and novel balance perturbations to assess the efficacy of reactive balance training. Methods: Participants: Community-dwelling adults with chronic stroke who could walk independently without a gait aid for at least 10 m. Interventions: Reactive balance training, using manual and internal perturbations, or 'traditional' balance training (control group). Training took place for one hour per session, twice per week for six weeks. Outcome: Proportion of unexpected slips triggered as intended; state anxiety, perceptions of situations, and participants' subjective responses to the unexpected slip perturbation; and spatiotemporal and kinematic features of unperturbed and perturbed walking (step length, width, and time, and mechanical stability) pre- and post-training. Randomisation: Blocked stratified randomization. Blinding: Assessors were blinded to group allocation. Results: Numbers randomised: 28 participants were randomized (15 to reactive balance training, 13 to control). Of these, nine reactive balance training group participants and seven control participants were eligible and consented to additional data collection for the pilot study. Numbers analysed: 12 participants (six per group) completed the post-training unexpected slip data collection and were included in analysis of the pilot objective. Outcome: All unexpected slips triggered as intended. Overall, participants did not report increased state anxiety or any concerns about the unexpected slip. Analysis of spatiotemporal and kinematic data suggested better stability following the unexpected slip for reactive balance trained participants than control participants; however, there were also between-group differences in spatiotemporal and kinematic features of walking pre- and post-training. Conclusions: Unexpected slips are feasible in research. However, their value as outcomes in clinical trials may depend on ensuring the groups are balanced on prognostic factors. Trial registration: ISRCTN05434601 Funding: Canadian Institutes of Health Research.