Long-lasting effects of electrical stimulation upon muscles of patients suffering from progressive muscular dystrophy

Ten patients with different forms of muscular dystrophy were included in the stimulation programme of the right tibialis anterior muscle for two to three months. Stimulation frequency of 8 Hz was used in six, and of 20 Hz in the other four patients. Muscle strength was estimated by means of an ankle brace which allowed measurements of torques in the ankle during short attempts (two to three seconds) of maximal voluntary isometric contraction in the direction of dorsal flexion of the foot. Muscle fatigue was assessed by the decrease of force during sustained (1 minute) maximal voluntary contraction. The measurements were carried out before the beginning of the stimulation programme (first), immediately after its conclusion (second) and 15-16 months later (third). At the end of the stimulation programme the mean increase of maximal torques was 24.9% in the stimulated, and 8.2% in the nonstimulated, extremity. Comparison of the results of the first and third measurements showed an average decrease of maximal torques of 12% in the stimulated, and of 21.3% in the nonstimulated, extremity. There was no change in fatigue.