Evaluation of TENS Based Biofeedback and Warning for Improvement of Seated Balance on a Trunk Rehabilitation Robot

Provision of visual feedback under unstable and forcefully perturbed seat conditions can help improve seated balance performance. However, due to visual limitations, some patients may require use of a different modality. Additionally, warning about an upcoming perturbation may improve balance reactions, and use of a system that provides such warnings and balance biofeedback through different modalities may result in further improvement. Transcutaneous electrical nerve stimulation (TENS), which can generate electro-tactile stimulation, may be useful in this regard. Therefore, in this study with 21 healthy subjects, we have used our recently developed trunk rehabilitation robot to evaluate the performance of TENS as a feedback and perturbation warning modality against visual and vibrotactile stimulation. The center of pressure (COP) and trunk acceleration results show that both TENS and vibrotactile stimulation may serve as viable alternatives for visual feedback under unstable condition. Under perturbation condition, provision of warning improves balancing performance, and TENS shows the overall best performance as a warning modality, with vibrotactile showing the lowest performance. Thus, TENS may be considered a feasible feedback/warning modality for use during seated balance rehabilitation.