Responses to untrained and unexpected balance perturbations following reactive balance training among people with chronic stroke: a feasibility study.

Trial design: Pilot study embedded within an assessor-blinded parallel randomized controlled trial.

Objective: To determine the feasibility and utility of using unexpected and untrained balance perturbations in future studies assessing the efficacy of reactive balance training (RBT) post-stroke.

Methods: Participants were community-dwelling adults with chronic stroke who could walk independently without a gait aid for > 10 m. Participants were assigned using blocked stratified randomization to six weeks of RBT or "traditional" balance training (control group). Outcomes were 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 pre- and post-training. Assessors were blinded to group allocation.

Results: 28 participants were randomized (15 RBT, 13 control). Nine RBT participants and seven control participants were eligible and consented to additional data collection for the pilot study. 12 participants (six per group) completed the post-training unexpected slip data collection and were included in analysis of pilot objectives. All unexpected slips triggered as intended. Participants did not report increased state anxiety or concerns about the unexpected slip. Spatiotemporal and kinematic data suggested better stability following the unexpected slip for RBT 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 balancing the groups on prognostic factors.

Trial registration: ISRCTN05434601.