Usability and Validation of the Smarter Balance System: An Unsupervised Dynamic Balance Exercises System for Individuals With Parkinson's Disease.

Conventional physical and balance rehabilitation programs to improve balance performance and increase postural stability are often limited due to cost, availability of physical therapists, and accessibility to rehabilitation facilities. Exercise compliance is also affected by a loss of memory and decline in motivation in prescribed home-based balance training. We have developed the smarter balance system (SBS) incorporating multimodal biofeedback (visual plus vibrotactile) intended for clinical and home-based balance rehabilitation and assessed its efficacy on physical therapists' recommended dynamic weight-shifting balance exercises (dynamic WSBE) in individuals with Parkinson's disease (PD). The SBS consists of a smartphone and custom belt housing a processing unit, miniaturized sensors, and vibrating actuators (tactors). Visual and vibrotactile biofeedback guidance during dynamic WSBE is generated by the SBS's custom app based on 90% of the user's limits of stability (LOS). Ten individuals with idiopathic PD having impaired postural stability participated in one unsupervised session comprising 24 trials of the dynamic WSBE in a laboratory setting. Participants' limits of stability (LOS) in the anterior-posterior (A/P) and medial-lateral (M/L) direction were measured at the pre- and post-session. To assess the efficacy of SBS to provide guidance during balance rehabilitation using dynamic WSBE, cross-correlation (XCOR), position error (PE), and percent of tactor activation (PTA) were measured. There was a significant increase in LOS between the pre- and post-training session in both A/P and M/L directions. The average XCOR across all participants were 0.87 (SD = 0.11) and 0.76 (SD = 0.11) for the A/P and M/L direction respectively. The average PE and PTA for the A/P direction was 1.17 deg (SD = 0.60) and 65.35% (SD = 15.1) respectively and 0.74 deg (SD = 0.28) and 31.3% (SD = 16.42) in the M/L direction respectively. There was no significant effect of trials for XCOR, PE, and PTA. Participants' LOS significantly increased after one session of the dynamic WSBE. Individuals with PD could accurately follow the target movements during the dynamic WSBE using the SBS. Future studies will assess the efficacy and acceptability of the SBS during long-term in-home rehabilitative training for balance-impaired individuals.