Effect of Strength Training with Enhanced Sensory Input on Quadriceps Voluntary Activation and Landing Performance in Subjects with Anterior Cruciate Ligament Injury

Abstract

Anterior cruciate ligament (ACL) ruptures often accompanied by severe quadriceps muscle atrophy and voluntary activation (VA) failure. It has been shown that additional enhanced sensory input (SI) with electrical stimulation (ES) could efficiently enhance the VA of the quadriceps muscle. The present study was aimed to investigate the effect of strength training with additional enhanced sensory input induced by ES on the voluntary activation, as well as the functional outcome in subjects with chronic ACL injury. Nineteen ACL injured subjects with VA below 90% were randomly divided into two groups: the strength training with additional SI group, and only the strength training (control) group. Isokinetic strength training program was conducted for three days per week, over a four weeks period. For the SI group, low intensity electrical stimulations were applied in the 30-minute strength training period. Maximum quadriceps isometric strength, voluntary activation, and single leg landings were performed before and after training. In the results, it was found that the maximum quadriceps strength, the VA and the maximal vertical ground reaction force were significantly (p＜.05) increased after training in both groups. The maximum knee flexion angle after landing remains unchanged in both groups. The strength training program has been shown to efficiently improve the quadriceps muscle strength, the central drive and the ability to support the body weight. The effect of strength training with additional enhanced sensory input by ES was similar to that of strength training alone.