Dursun et al. [13] applied universal treatment and treatment in combination with EMG biofeedback to 60 PFPS patients for improvement in balance between the VMO and VL, and reported that VMO/VL muscle activity ratios significantly increased in the group which received treatment in combination with EMG biofeedback compared to the control group. In the present study, all the groups’ VMO/VL muscle activity ratios became close to 1:1 after the intervention, but the muscle activity ratios significantly increased in the closed kinetic exercise group which used EMG biofeedback relative to the closed kinetic exercise group. This is regarded because EMG biofeedback enabled self-control of muscle activity and improved muscle control and response ability, more effectively influencing decrease in muscle fatigue and improvement in muscle activity ratios than the other interventions.