The effect of visual feedback on EMG activity of the knee joint muscles during closed kinetic chain exerc

Objective: In this study, to investigate the effect of a closed kinetic chain exercise of the lower extremity on muscle activity of the knee joint muscles, participants were randomly assigned to two groups and subjected to squat exercises with or without visual feedback. Method: The squat exercise group provided with visual feedback performed squat exercises in front of a mirror while stickers were attached at the elbows(olecranon), greater trochanters, and knees. However, the squat exercise group blocked from visual feedback performed the same exercise with a blindfold. Both groups exercised 3 times a week for 30 minutes per session for 6 weeks. Results: The muscle activity of the squat exercise group with visual feedback and the squat exercise group without visual feedback showed interaction effects in the rectus femoris(RF), biceps femoris(BF), and vastus medialis(VM) according to the period and between groups(p<0.05); however, no interaction effect was found in the vastus lateralis (VL)(p>0.05). In addition, both the RF/BF ratio and the VM/VL ratio showed interaction effects according to the period and between groups(p<0.05). Conclusion: In conclusion, although both groups showed changes in muscle activity after the exercise, the squat exercise group provided with visual feedback showed more changes in muscle activity. This suggests that the exercise method provided with feedback was more effective. This finding is expected to help develop new and diverse sensory simulation-based exercise programs in the future.