Use of Electrical Stimulation to Enhance Recovery of Quadriceps Femoris Muscle Force Production in Patients Following Anterior Cruciate Ligament Reconstruction

BACKGROUND AND PURPOSE: Electrical stimulation has been shown to be effective in aiding the recovery of quadriceps femoris muscle force production after anterior cruciate ligament reconstruction. The actual dosage of stimulation (training intensity) has not been well described. The purpose of this investigation was to establish a dose-response curve for electrical stimulation regimens designed to improve quadriceps femoris muscle recovery in patients after anterior cruciate ligament reconstruction. SUBJECTS AND METHODS: We analyzed data from a subsample (n = 52) of patients receiving electrical stimulation (N = 110) who were involved in a large, multicenter randomized clinical trial investigating treatment strategies designed to enhance quadriceps femoris muscle recovery. Fifty-two subjects (40 male, 12 female), with an age range of 15 to 43 years (mean = 25, SD = 7), participated in 4 weeks of quadriceps femoris muscle training using either portable, battery-powered home stimulators or console stimulators designed for clinical use. Training intensities were monitored by logging the electrically elicited knee extension torque and expressing this torque as a percentage of the uninvolved quadriceps femoris muscles' maximal voluntary contraction force. After the 4 weeks of training, isometric muscle torque was assessed and a dose-response curve was generated. The relationship between training intensity and quadriceps femoris muscle torque was assessed with Pearson Product-Moment Correlation Coefficients. RESULTS: A significant, linear correlation was found between training intensity and quadriceps femoris muscle torque. Subjects training with console, clinical generators trained at higher intensities than those training with portable, battery-operated generators; such training resulted in higher quadriceps femoris muscle torque. CONCLUSION AND DISCUSSION: These results support the use of high-intensity electrical stimulation and do not support the use of low-intensity or battery-powered stimulators when the goal is recovery of quadriceps femoris muscle force production in the early phases of rehabilitation after anterior cruciate ligament surgery. [Snyder-Mackler L, Delitto A, Stralka SW, Bailey SL. Use of electrical stimulation to enhance recovery of quadriceps femoris muscle force production in patients following anterior cruciate ligament reconstruction.