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 stimulation (ES) on the contractile characteristics of the triceps surae muscle. A selection of 12 subjects was divided into two groups (6 control, 6 experimental). The ES sessions were carried out using a stimulator. Flexible elastomer electrodes were used. The current used discharged pulses lasting 200 microseconds at 70 Hz. Contraction time was 5 s and rest time 15 s. The session lasted 10 min for each muscle. Training sessions were three times a week for 4 weeks. Biomechanical tests were performed using an isokinetic ergometer. Subjects performed plantar flexions of the ankle over a concentric range of movement at different angular velocities (60, 120, 180, 240, 300, 360 degrees.s-1) and held isometric 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 evenly upwards under the influence of ES (P < 0.05). The increased force during the "after" test was greater (P < 0.05) for ankle angle positions of 15 degrees and -30 degrees, which demonstrated a link between the training angle and the gain in strength. No change was noted in the cross-sectional area of the muscle. The results showed that ES allowed the contractile qualities of muscle to be developed in isometric and dynamic conditions. Nervous mechanisms can account for most of these adaptations.