Improving the efficiency of physical exercises for knee using biofeedback

Impairments occurred in the knee result in the decline of the quality of daily activities such as walking, running, sitting, and standing. Depending on the level of impairment, physical exercises are subscripted to regain strength, flexibility, and range of motion. The efficiency of the exercises can be improved by supplying a feedback mechanism during the exercises. Meanwhile, some improvements can be obtained when the knee joint range of motion is assessed during the exercises. The development of automated systems having feedbacks and motion assessments is gaining increased demand. This thesis work aims to improve the efficiency of physical exercises for the knee by quantifying the knee joint range of motion with the use of two micro-electro-mechanical orientation sensors, and by giving audio feedback by playing predetermined dialogues with the use of an audio player module. Fifteen volunteers are enrolled to analyze the effectiveness of the audio feedback on three physical exercises namely sit-to-stand, squat, and seated leg flexion-extension. The Wilcoxon rank-sum test results for seated leg flexion-extension exercise, sit-to-stand, and squat exercise shows that the addition of audio feedback shows a statistically significant difference in sit-to-stand (p=.01) and squat exercises (p<.001) but not in seated leg flexion-extension exercise (p=.15). The System Usability Scale (SUS) results show that exercise with audio feedback (SUS score=83.0) has a higher score than exercise without audio feedback (SUS score=72.2), but this increase is not statistically significant (p=0.14). The addition of audio feedback in closed chained exercises may increase the efficiency of the physical exercises. This improvement may be seen more drastic in the exercises that do not end with the movement of locking the knee in full flexion or extension. Future studies are planned to compare the designed system with video-based feedback systems used in physical therapy and to examine the effects of audio feedback on knee-based physical therapy with volunteers requiring physical rehabilitation rather than healthy volunteers.