EFFECT OF ELECTRICAL-STIMULATION TRAINING ON THE CONTRACTILE CHARACTERISTICS OF THE TRICEPS SURAE MUSCLE

This study aimed to assess the effects of training using electrical st imulation (ES) on the contractile characteristics of the triceps surae muscle. A selection of 12 subjects was divided into two groups (6 con trol, 6 experimental). The ES sessions were carried out using a stimul ator. Flexible elastomer electrodes were used. The current used discha rged pulses lasting 200 mu s at 70 Hz. Contraction time was 5 s and re st time 15 s. The session lasted 10 min for each muscle. Training sess ions were three times a week for 4 weeks. Biomechanical tests were per formed using an isokinetic ergometer. Subjects performed plantar flexi ons of the ankle over a concentric range of movement at different angu lar velocities (60, 120, 180, 240, 300, 360 degrees.s(-1)) and held is ometric contractions for 5 s at several ankle flexion angles (-30/-15/ 0/15 degrees-0 corresponded to foot flexion of 90 degrees relative to the leg axis). The force-velocity relationship was seen to shift evenl y upwards under the influence of ES (P<0,05). The increased force duri ng the ''after'' test was greater (P<0,05) for ankle angle positions o f 15 degrees and -30 degrees, which demonstrated a link between the tr aining angle and the gain in strength. No change was noted in the cros s-sectional area of the muscle. The results showed that ES allowed the contractile qualities of muscle to be developed in isometric and dyna mic conditions. Nervous mechanisms can account for most of these adapt ations.