1969 Volume 14 Issue 2 Pages 98-102
Several researchers have tried the experiments on positive and negative works from the view point of tile energy consumption. Those results showed the same inclination that while the energy cost at the positive work increased according to the amount of the load, that at the negative work was constant over a wide range. The purpose of this study was to reveal this inclination from the view point of the electrical activity of muscles. The experimental subject was a healthy adult man (35 years old). The subject supported the various weights (2,4,6,8kg) with his wrist in sitting position isotonically. Action potential recordings were made from the elbow flexors using the standard surface electrodes. Integration was performed with Miller's circuit (reported in I). The angular velocity of the elbow joint was determine by the electrogoniogram. By the use of rhythmical movements, the subject made contractions of a certain velocity. Contraction velocities were from 30 to 30O degrees per second in both shortening and lengthening of the muscle. The range of the movement of elbow joint was about 70 degrees from 60° to 130° in each trial, but integration was observed in 30 degrees from 80°to 110°. The results were as follows; 1) At constant tension oof shortening or lengthening, the total electrical activities linearly decreased with velocity. But the electrical activities per second increased with velocity in shortening and remained almost constant in lang thinning. 2) At constant velocity of shortening or lengthening, the electrical activity per second increased according to the amount of tension. The more the slope of this relation was, the higher the velocity of contraction was in shortening (positive), though there was little difference in lengthening (negative).
