Isometric contractions of normal and spastic human skeletal muscle.

Isometric contractile properties of human elbow flexor muscles were examined in 27 normal subjects (7 females and 20 males). Contractions of elbow flexors were elicited by application of electrical pulses to the biceps motor points. The tension development was recorded at the wrist with the elbow angle fixed at 90 degrees--100 degrees. The data for the time to peak and time to half relaxation of the twitch, the twitch tension-to-tetanus tension ratio, and the posttetanic twitch potentiation are reported. The contractile properties of spastic elbow flexor muscles from 7 subjects who had been hemiparetic for periods ranging from 4 months to 60 months were found to be similar to those of muscles in normal subjects and unaffected muscles in hemiparetic subjects.