Efficacy of Electromyographic Biofeedback in the Recovery of the Vastus Lateralis after Knee Injury: A Single-Group Case Study

Electromyographic biofeedback (EMG-BF) is a technique that can contribute to the improvement of muscle tone and control in the rehabilitation process after injury. The aim of this research was to determine the effectiveness of EMG-BF in increasing the electromyographic activity of the vastus lateralis after knee injury. The sample consisted of four individuals who had undergone surgery or rehabilitation to resolve either a partial meniscal tear or a patellar tendon strain. The intervention consisted of a program of ten sessions of EMG-BF work. Twelve trials were performed in each session, in which participants were instructed to target the muscle tension produced by the vastus lateralis of the uninjured hemilateral limb. Of the twelve trials in each session, the first three and the last three were performed without feedback, and the intermediate six with feedback. The recording of muscle activity was performed using CY-351/2 Mioback equipment, which allowed the amplitude of the electromyographic signal to be evaluated. The results indicated that the sample analyzed reached greater amplitude during the biofeedback trials, both for the maximum (Z = −13.43, p < 0.001, Cohen’s d = 0.64, 95% CI (0.27, 1.01)) and mean (Z = −7.26, p < 0.001, Cohen’s d = 0.24, 95% CI (−0.12, 0.60)) values. The amplitude also increased throughout the ten sessions, both for the maximum (Z = −3.06, p < 0.01, Cohen’s d = 1.37, 95% CI (0.29, 2.45)) and mean (Z = −3.06, p < 0.01, Cohen’s d = 1.20, 95% CI (0.34, 2.08)) values. Thus, the results highlight the efficacy of this technique in improving muscle activity, suggesting that it is a useful therapeutic procedure in injury recovery.