抄録
Using the integrator described, in the previous report the authors intended to compare the negative and the positive works done in the various types of the movement from the view point of EMG. The movements are the popular ones such as chinning, two hands curl, going up and down stairs, pedaling, squat and jumping. The elbow flexors are picked up in the two formers and the knee extensor and the ankle extensor in the four latters. Recording was carried out as follows; 1) EMG and its integration were recorded by the standard surface electrodes. 2) Motion patterns for the elbow, knee and ankle joints were recorded by the electrogoniometer. 3) Tension or pressure was recorded by the semi-conductive straingage. In the case of chinning, the subject grasped the horizontal bar with underhand grip and pull up the body from a full arm extension position to the position at which the chin was above the bar. This was the positive work for the elbow flexors. Then the subject extended the arm to the original position. This was the negative work for the elbow flexors. Those movement were done very slowly and at the same speed. Fig.5 shows the recordings of EMG, its integration and electrogoniogram at chinning. It is clear that at flexion (positive work) is about two or three times larger than at extension (negative work). The same results were seen in the other movements. Namely, the magnitude of the action potentials of the muscle was always larger in shortening (positive) than in lengthening (negative), if exerting the same force at same speed.
