Evaluation of a Personal Mobile Trainer System Designed for Facilitating Exercise Therapy for Traumatic Brain Injury Patients

Abstract

There are no effective pharmacological agents that can prevent or treat post-TBI cognitive deterioration. Previous research has shown that exercise can be an effective means of enhancing the patients condition with mild traumatic brain injury (TBI). However, compliance with the prescribed exercise regimen has been low, as TBI patients often suffer from poor executive function and need assistance with complying with their prescribed exercise program. This study aims to design, build, and test a system based on a wearable exercise tracker to assist and encourage patients by facilitating doing the prescribed exercises at a place and time that is convenient to the patient. It is hypothesized that such a personal mobile trainer (PMT) system increases the compliance level of TBI patients with their prescribed exercise. A PMT system using a commercially available wrist-worn fitness tracking (WFT) device was designed and built. To choose a suitable WFT for the project, four most popular WFT’s were evaluated for their accuracy of measuring heart rate: 1) Apple Watch (AW); 2) Polar Watch (PW): 3) Fitbit (FB); and 4) Samsung Watch (SW). Recording heart rate from 5 volunteer healthy subjects (2F & 3M; age 26.43.20 years; BMI 24.71.92 kg/m2) while doing a 5-min of fast walk, as perceived by a volunteer, on a treadmill while using the WFT’s and concurrently recording the heart rate by an electrocardiogram (ECG) showed that AW had the lowest least mean squared error (AW=3.98±1.74; PW=20.9±14.6, FB=27.74±14.0, SW=62.6±73.6). Hence, AW together with Apple iPhone was chosen to design the PMT for monitoring TBI patients exercise activity and to provide encouragements and reminders to assist patients to stay with their prescribed exercise program. Custom built software for AW and iPhone was developed to provide a patient interface both on AW and iPhone. Further, communication software was developed to transmit the collected data to a cloud-based server to make the status of the patient compliance instantly available to the attending clinicians. To test the said hypothesis using the proposed PMT system, we tested the system on 9 participants (7 males, 2 females, aged 55.2 ± 7.5 years, BMI 28.4 ± 5.0 lb./in2) with TBI (3 with mild physical disability and six without physical disability) for 3 months. Two measure of compliance was devised that measure the percentage of the duration that the subjects performed the prescribed exercise (Duration Compliance, 80.64%±17.23%) and the percentage of achieving the prescribed heart rate (Hear Rate Compliance, 55.68%±33.80%). These results showed that the PMT system could increase TBI patient's adherence to prescribed physical exercises. Investigators have shown that improvement in cognitive function may be associated with improved heart rate variability (HRV) [1]. Hence, time and frequency domain HRV metrics for the patient sample population was measured using a 5-min ECG recording while TBI patient rested in supine position both at prior to patients start the 3-month exercise program and at the conclusion of the exercise program. No change in either time or frequency domain HRV metrics was detected. As the p-values for comparison in time domain was 0.94 and for comparison in frequency domain was 0.60. Additionally, we studied the active energy value in kilocalories that was measured by AW and recorded in the PMT cloud-based system for each patient. A strong positive correlation was obtained between the exercise duration and active energy measurements (R-value=0.94±0.7) and between the Duration Compliance and the active energy measurements (R-value=0.85±0.12). Finally, the patient's subjective ratings of the designed PMT system were studied using the System Usability Scale (SUS). The patients filled out the SUS surveys at the conclusion of their 3-month exercise program. The SUS average score for t