Limitations and future directions
stroke, short-term motor learning or retention
STROKE
The limitations of our study included a small sample size, short duration of 60 s gait trials, and the use of a handrail during walking. The short walking bouts were related to the goal of the study being focused on evaluating immediate effects of biofeedback, and not short-term motor learning or retention. Another limitation was that due to the known biomechanical relationships between AGRF and TLA, and our previous findings that AGRF biofeedback induces concomitant increases in TLA, we had concerns that the introduction of TLA biofeedback first would elicit a learning strategy of exposing the individual to a specific biomechanical strategy to improve their AGRF. We, therefore, did not randomize the order of feedback trials in the current preliminary study, which is another methodological limitation. We posited that the introduction of AGRF biofeedback trial first, using the cue “push into the ground harder”, would incur lesser risk of eliciting specific biomechanical strategies in the subsequent TLA feedback gait trial. Future studies should investigate the appropriate dosage of biofeedback, long-term effects of biofeedback training, neurophysiologic correlates underlying the effect of biofeedback, and evaluate overground gait training with biofeedback. Additionally, future studies should explore the effect of gait biofeedback when variability in stroke severity or chronicity is accounted for. Lastly, longer exposure to gait biofeedback (e.g., multiple 6-min training bouts) will enable future investigations to evaluate retention of biofeedback-induced improvements in gait biomechanics, and potentially identify characteristics of responders versus non-responders to biofeedback.