The Benefits to Adjust Ground Slopes during Squat Exercise for Rehabilitation : Based on the Weighting of Muscle Activation across the Slope

Abstract

Purpose: The purpose of this study is to inverstigate the changes in muscle synergy and muscle weightings during sqaut exercise on different ground slopes and propose the goal-directed squat exercise as a rehabilitation method. Methods: Tweleve healthy young adults with an average age of 21.45 ± 1.03 years, and body mass index of 24.21 ± 4.01kg/m2 performed squat exercises on 3 different slope boards(i.e. flat, 10-degree incline, 10-degree decline ground slope). The squat exercise on each ground slope condtion was performed 10 trials with a rest time of 30 seconds between the conditions. During the squat exercise, muscle activation of tibialis anterior (TA), multifidus (MUL), gastrocnemius (GCM) and internal oblique (IO) muscles were measured and included in muscle synergy analysis using ICAPCA. Results: As a result, three synergies of all participants were extracted and there was no significant difference in variance accounted for(VAF) of each synergy, indicating the complexity of muscle synergy between the ground slope condition. However, during exercise on the incline slope ground, there were sigfniciant lower TA muscle weighting of synergy 1 (P=0.020) and higher IO muscle weighting of synergy 2 (P=0.005) than flat ground. Furthremore, during exercise on the decline slope ground, a significant lower TA muscle weighting of synergy 2 (P=0.017) was found when compared with the incline slope ground. Conclusion: In conclusion, the findings of this study suggest that squat exercise on incline slope ground will be recommended for training lower extremity muscles above the ankle and abdominal core muscles, and decline slope ground will be recommended for training balance abiltiy, especially, in the elderly.