[Muscle electric stimulation in sports medicine]

Neuromuscular electrical stimulation (NMES) is frequently used to strengthen the normal muscle. In medicine, several investigators have highlighted the value of NMES when treating amyotrophy related to immobilization. The efficacy of NMES of the quadriceps during rehabilitation following anterior cruciate ligament surgery has been well documented. These electrical stimulation programs are composed of stimulation--rest cycles and are performed with the aid of percutaneous electrodes situated in regard to muscle motor points. The stimulation frequency is chosen to induce tetanic contractions and is generally situated between 50 and 100 Hz. During NMES, the trainer or the physiotherapist can accurately modulate a large number of parameters but the sensory discomfort linked to the current intensity remains the major limitation for strength improvement. In the context of rehabilitation, the association of NMES with voluntary exercises is superior to the isolated utilization of the classic program composed of isometric voluntary contractions. To explain this advantage of associating NMES with voluntary contractions, it has been hypothesized that the electrically induced contractions impose specific patterns of muscle recruitment and a particular metabolic solicitation.