Effects of chronic low frequency electrical stimulation on normal human tibialis anterior muscle.

The loss of force that occurred during intermittent electrically evoked tetanic contractions was determined for the tibialis anterior muscle of normal subjects. Adult muscles showed a characteristic reduction of tension over the first two to three minutes until a steady plateau was reached. Muscles of young children showed no comparable decrease of the initial tension in response to this method of fatigue testing. After fatigue the muscles of both groups of subjects produced a higher proportion of tension at lower rates of stimulation. Following prolonged chronic low frequency stimulation at 8-10 Hz, adult muscles showed a significant increase (p less than 0.01) in fatigue resistance compared to unstimulated control: the muscles of the normal child showed no measured change. It is concluded that it is possible to alter the properties of adult human muscle by superimposed low frequency electrical stimulation.