This study examines static/dynamic balance performance, daily activities, and confidence in less fear of falling for people with Parkinson's disease (PD) performing in-home balance exercises with a smartphone-based wearable telerehabilitation system (intervention group) compared to typical paper-based balance exercises (control group). Twenty-two subjects with idiopathic PD will be randomly assigned to either of two groups of eleven (intervention group (IG) and control group (CG)). The experimental design will include laboratory assessments (i.e., pre-assessment baseline at the beginning of week 1, post-assessment at the end of week 6, and retention-assessment 1 month after week 6) and in-home balance exercises. IG and CG will perform in-home balance exercises (3 days per week for 6 consecutive weeks) with the Smarter Balance System (SBS) recently developed by the PI or the paper-based regimen, respectively. Both groups will also use Fitbits for 6 weeks.

Laboratory assessments: Subjects will be quantitatively assessed for static/dynamic balance performance using a measure for the range of limits of stability (LOS) in both anterior-posterior (A/P) and medial-lateral (M/L) directions, and a Sensory Organization Test (SOT) consisting of six conditions (1: Normal vision and fixed support; 2: Absent vision and fixed support; 3: Sway-referenced vision and fixed support; 4: Normal vision and sway-referenced support; 5: Sway-referenced support and absent vision; and 6: Sway-referenced vision and sway-referenced support) using a Balance Master® (NeuroCom International Inc., USA). During the SOT, center of pressure (COP) data as a function of the six SOT conditions will be collected at a rate of 100 Hz for postural sway analysis. After the completion of quantitative balance assessments, balance performance will be qualitatively assessed using the Activities-specific Balance Confidence (ABC) scale and the Falls Efficacy Scale (FES). A modified Community Health Activities Model Program for Seniors (CHAMPS) will be used to collect the levels of exercise and non-exercise physical activity. After completion of the pre-assessment, a member of the research team will train subjects to use the SBS's smartphone and the Fitbit. Only the IG will be additionally trained in the use of the custom belt and the walker and multimodal biofeedback for in-home dynamic WSBE guided by the SBS. For CG subjects, the physical therapist (Co-I) will review the paper-based regimen for in-home dynamic WSBE. After completion of the post-assessment, only the IG will complete a usability and acceptability questionnaire (UAQ) for the SBS.

In-home balance exercises: Both groups will use the SBSs and Fitbits for 6 consecutive weeks. Only the IG will complete in-home dynamic weight-shifting balance exercises (i.e., physical therapists' recommended dynamic balance exercises, hereafter dynamic WSBE) with the SBS (3 days per week). The CG will perform dynamic WSBE following the paper-based regimen (3 days per week) in accordance with the Health Professionals' Guide to the Physical Management of Parkinson's disease, including detailed descriptions regarding stance condition, movements in both A/P and M/L directions, and repetitions. Only the CG will use the SBS's smartphones and the Fitbits (the SBS's custom belt will not be provided to the IG). To assure a safe exercise environment, both groups will perform in-home dynamic WSBE by standing inside a walker (no wheels). For the IG, the instructional video provided by the SBS will show how to perform dynamic WSBE in both A/P and M/L directions by standing inside the walker without touching or holding onto it unless the subject experiences loss of balance. For the CG, paper-based instructions will be provided. Both groups will be instructed to continue taking prescribed PD medication. After each trial, the IG smartphone app will store exercise-related data. The IG and CG smartphones will store physical activity data (daily number of taken steps and associated distance) collected from the Fitbit.

Performance metrics: Measured data from the Balance Master®, the SBSs, and the Fitbits will be analyzed using MATLAB (The MathWorks, USA). As a function of the pre/post/retention-assessments, two primary outcome measures (range of LOS and SOT score) will be used to evaluate static/dynamic balance performance. Ranges of LOS in degrees correspond to the furthest deviations of the body tilt in both A/P and M/L directions. The SOT score that can be directly obtained from the Balance Master® ranges from 0 to 100, where 100 indicates no postural sway and 0 indicates a fall. The four supplementary outcome measures, which are standard metrics for assessing balance performance, are a root mean square of postural sway (RMS sway) in both A/P and M/L directions, elliptical area of postural sway (sway area), and approximate entropy of postural sway (sway ApEn). Both RMS sway and sway area are linear measures of balance performance, and the sway ApEn is a non-linear measure quantifying the complexity and regularity of postural stability. For the IG, the UAQ score (Likert scale) will be used to assess the usability and acceptability of the SBS, and the IG's compliance with the in-home balance training regimens, total exercise time, and number of completed exercises will be quantitatively analyzed. For both groups, daily number of taken steps and associated distance obtained from Fitbits and ABC scale, FES, and CHAMPS score will be analyzed.