After validation of the proposed wearable real-time feedback (WRTF) system, the feasibility of utilizing this system to provide RTF of gait and posture parameters will be tested in a single group of twenty-six people with mild to moderate Parkinson's disease (PD). The sample size was chosen to observe an intra-class correlation coefficient (ICC (2,1)) value between 0.75 and 0.9 at alpha = 0.05 and power of 80%. Subjects of all races and both genders will be recruited. Despite higher representation of males in PD, the investigators will seek to achieve an equal distribution of males and females. As the incidence of PD increases with age, rising after the age of 55 years with a sharp increase after 60 years, the investigators will recruit participants between the ages of 50-80 years.
After enrollment, each subject will participate in one screening and clinical evaluation session at Muhammad Ali Parkinson Center (MAPC) at St. Joseph's Hospital and Medical Center (SJHMC) in Phoenix, AZ and all the experimental data collection sessions will be performed at the Arizona State University (ASU), Tempe, AZ. The 3 experimental data collection sessions will be (1) Validity Session, (2) Continuous feedback (CF) Mode Session, and (3) On-demand feedback (ODF) Mode session. All the screening, clinical evaluation, experimental data collection sessions will be carried out during subject's "medication-on" state (when the medication best controls symptoms of PD, usually 60-90 minutes after the subjects' usual dose of anti-parkinsonian medication). The order of CF and ODF mode sessions will be randomized across the subjects.
Screening and Clinical Evaluation Session (\~ 2 hours): In this session, first the subjects will be screened by Dr. Shill for the eligibility criteria which includes UPDRS evaluation. If they are eligible, their balance and cognitive status will be evaluated using the Mini-Balance Evaluation Systems Test (Mini-BESTest) and the Scales for Outcomes of Parkinson' Disease-Cognition (SCOPA-Cog) respectively. The Mini-BESTest has been shown to detect even subtle balance deficits in people with PD. SCOPA-Cog is a PD-specific scale that tests non-verbal and verbal memory, learning, attention, and executive function, including complex motor planning, working memory, and verbal fluency and has undergone extensive clinimetric testing.
WRTF Concurrent Validity Session (SA1) (\~ 2 hours): In this session, MIMU sensors will be placed on the lower legs, wrists, lower back, and upper back. Lightweight reflective markers will be placed according to the full-body marker setup (Vicon Motion Systems, Ltd, UK) and specialized software (Nexus 2.3, Vicon) will be used for kinematic assessment. Participants will be asked to complete twenty 15-meter overground walking trials at their self-selected comfortable speed. From the steady state segments of these trials, the gait events, spatio-temporal gait indices (including step length, step time, arm swing, and back angle) will be calculated in real-time for each step using the WRTF system (as described in earlier sections), and will be compared against the gold standard values obtained from Vicon system.
Continuous Feedback Mode Session (SA2) (\~ 3 hours): In this session, RTF will be provided for the participant to practice walking with increased step length, arm swing, upright posture and regular step time. All the walking trials will be performed overground and feedback of only one parameter will be provided at a given time/trial. Various step-to-step spatio-temporal gait and posture measures will be obtained using the WRTF system.
First, the participants will be asked to walk at their self-selected speed for one 80-meter trial (with a 180 degree turn at 40-meter) in a long hallway to determine their baseline gait measures (including step length, arm swing, step time, and back angle). Then, the subjects will perform one 80-meter trial stepping on visual cues - strips placed on the floor at equal intervals, to obtain the step length target template (described in the 'Continuous Feedback Mode' section). Next, the subjects will be asked to walk two 80-meter trials during which they will be provided with RTF of their step length performance (their current movements in a sound form and specific instructions through conducting ear phones). Following this, participants will perform one 80-meter trial following a metronome to obtain the step time target template which will be followed by two 80-meter trials during which RTF of their step time will be provided to improve gait rhythmicity. Similarly, the trials for arm swing and upright posture will be performed as follows: one 80-meter trial (walking with bigger arm swings) to obtain the arm swing target template, two 80-meter trials providing RTF of arm swing performance, one 80-meter trial (walking upright) to obtain the uprightness target template, and two 80-meter trials providing RTF of upright posture.
On-Demand Feedback Mode Session (SA3) (\~ 3 hours): This session will evaluate the use of on-demand feedback. After wearing the sensors of the WRTF system and ear phones, the subjects will perform one baseline 100-meter trial without feedback at their self-selected comfortable speed. Then, the subjects will participate in eight 100-meter trials with a 180 degree turn at 50-meters, of which, two trials will be performed with each type of feedback (step length, step time, arm swing, or upright posture). Spatio-temporal gait indices will be calculated from non-feedback and feedback trials. Sufficient rest periods will be provided between the trials.
Primary and Secondary Outcome Measures: The main primary outcomes will be intra-class correlation (ICC) and reliability coefficients (RC) to test the validity of the WRTF system. The other primary measures will be step length and time and their variability, arm swing, and upright posture. Also, correlations between cognitive status and balance control and ability to follow RTF will be explored.
Data and Statistical Analyses: For gait, mean values of step/stride length, asymmetry, variability in step length and time, gait speed, swing time, double support duration, and gait related items of clinical scores will be calculated. The posture control measures will include back angle during walking trials and time duration of maintaining different balance tasks during Mini-BESTest evaluation. Concurrent (criterion-related) validity between the two systems (WRTF vs. Vicon) will be analyzed with ICC (2,1) and RC. The effect of RTF (CF and ODF) on each primary measure will be assessed using paired t-tests. The difference in the degree of improvements between CF and ODF modes will also be compared by the application of paired t-test on the changes in gait and posture measures between respective feedback trials and baseline trials. For conditions violating normality, Wilcoxon signed-rank test will be used.
