Force Feedback-Based Gamification: Performance Validation of Squat Exergame Using Pneumatic Gel Muscles and Dynamic Difficulty Adjustment

Exergames have been considered an advanced ap- proach for enhancing the physical activities of the elderly community. Advancement includes greater immersive and en- joyment factors, which compute performance validation and sustain engagement to activate them from sedentary lifestyles. As a result, an at-home-based game design combined with squat workouts is essential to enhance lower-limb performance. We designed a virtual reality (VR) based exergame with dynamic difficulty adjustment (DDA) conditions in which the speed of the moving objects and air pressure of the PGM vary with respect to the knee shakiness feature. This letter aims to estimate the muscle loading and unloading effects of exergaming sessions at the onset and during the squat phase of the squat cycle. We acquired surface electromyography (sEMG) of five major lower limb muscles for seven subjects to evaluate the significant reduction in muscle activity during conventional and exergame- based squat sessions. In addition, we assessed the knee indicators to identify the variation in motion performance. The subjects performed 120 squats per session, followed by a maximum voluntary contraction (MVC) task. No adverse events, such as fatigue and dizziness, were reported during the study. Our results show a higher significant p<0.01 muscle activity difference for all tested muscles. We also found that knee shakiness showed a statistically significant reduction of p<0.01 during exergaming sessions (2 and 3) compared to the conventional squat.