Effect of Electromyographic Biofeedback on Quadriceps Neuromuscular Function in Patients With Quadriceps Inhibition

Study Summary

Muscle inhibition prevents optimal contraction of the quadriceps muscle due to changes in the nervous system after knee joint injury. Current treatments for muscle inhibition at this time include knee joint cryotherapy and electric stimulation prior to exercise. These treatments, in addition to strengthening exercises, have shown improvements in the quality and strength of muscle contractions however, they have a short window of effectiveness. Electromyographic Biofeedback is proven to be useful in improving quadriceps strength but the mechanism of action remains somewhat unclear. Therefore, the purpose of this investigation is to compare the effectiveness of electromyographic biofeedback supplemented exercise when compared to traditional exercise on quadriceps muscle function in individuals with a history of knee injury and current evidence of quadriceps inhibition. We hypothesize that 14 days of electromyographic biofeedback supplemented exercise will lead to larger gains in quadriceps activation when compared to traditional exercise. Thirty 18-40 year old participants with a history of knee injury and current evidence of quadriceps muscle inhibition will be enrolled in this single blind randomized controlled trial. Participants will provide written consent prior to all study procedures. Following enrollment, participants will be asked complete questionnaires related to knee related function, current levels of pain, and current activity level followed by completion of baseline measurements. 1. We will use the superimposed burst technique to quadriceps muscle activation. 2. We will measure the Hoffmann reflex response of the quadriceps with surface electromyography. We will measure this signal with surface electromyography electrodes that record the activity of the quadriceps muscle through the skin. Participants in both groups will be instructed on a 14 day home exercise protocol on the day of enrollment. The protocol is comprised of 4 exercises focused on both

Primary Outcome

Subjects will be secured to a chair (Biodex multi-mode dynamometer) with their knees and hips bent to approximately 90-degrees. Subjects will perform a maximal, voluntary isometric knee extension contraction (MVIC) with continuous verbal encouragement from the tester. Once the MVIC reaches a plateau (representing subjects' maximal effort) an electrical stimulus will be manually triggered and delivered directly to the quadriceps through 2 stimulating electrodes which will be secured to the subjec

Interventions

• DEVICE Electromyographic Biofeedback
• BEHAVIORAL Traditional Exercise