EQUAL EFFECTIVENESS OF ELECTRICAL AND VOLITIONAL STRENGTH TRAINING FOR QUADRICEPS FEMORIS MUSCLES AFTER ANTERIOR CRUCIATE LIGAMENT SURGERY

Neuromuscular electrical stimulation and voluntary muscle contraction are two exercise modes widely used in rehabilitation to strengthen ske letal muscle. Since there is debate as to which mode is most effective , we compared electrical stimulation with voluntary contraction perfor med at matched intensities following reconstructive surgery of the ant erior cruciate ligament. Forty men and women, aged 15-44, were randoml y assigned to either an electrical stimulation or a voluntary contract ion group. None of the subjects had a previous history of neuromuscula r injury. The subjects received treatment for 30 minutes a day, 5 days a week, for 4 weeks. Knee extension torque was monitored during treat ment to try to match the absolute muscular tensions (quantified as ''a ctivity'') achieved during therapy. To match the activity of the subje cts in the electrical stimulation group, who were treated al the highe st stimulation intensity they could tolerate, the subjects in the volu ntary contraction group were paced at progressively increasing intensi ties corresponding to 15, 25, 35, ana 45% of the injured limb's maximu m voluntary torque during weeks 1, 2, 3, and 4, respectively. We found no significant difference between the groups in terms of maximum volu ntary knee extension torque throughout the study period. In addition, 1 year after surgery, there was still no significant difference betwee n groups with regard to knee extension torque (p > 0.4). These data su ggest that neuromuscular electrical stimulation and voluntary muscle c ontraction treatments, when performed at the same intensity, are equal ly effective in strengthening skeletal muscle that has been weakened b y surgical repair of the anterior cruciate ligament.