Teaching Methods of Performing Ukemi in Judo by Means of EMG Analysis

Abstract

The performances of YOKO-UKEMI styles during falls in judo were analyzed by means of electromyogram and cinematography for to developments to protect the head from falls shock.
The subjects of the study were three well-trained players and five beginners in judo who volunteered to cooperate. These performance were classified in three ways: 1) falling from a squatting position, 2) falling after being lifted 70cm from the floor with supine position, 3) falling after hizaguruma. The subjects were instructed to keep pressing the mat after slapping hand (press-type ukemi) and to lift up the hand (pull-type ukemi) immediately upon body contact with mat after slapping hand.
For the purpose of the falling test, the relationship between elbow, shoulder muscles and neck muscles were examined by used recording VTR and EMG. The subjects elbow and shoulder joints were flexed and extended quickly. During this test, they were sitting in a chair, eyes closed.
For comparative examination of ukemi styles, one group of junior high school students were instructed to look at the knots in their belts during performance of ukemi, and another group of them to perform the pull-type ukemi.
The results are as follows;
1) After contacting the hand to the mat, the electrical discharges of left and right muscle sternocleidmastoids appeared more markedly in both well-trained players and beginners when performing the pull-type ukemi than the press-type ukemi. This result suggests that the occiput of subjects were protected from falls shock to the mat by pull-type ukemi.
2) During the pull-type ukemi neck flexions appeared greatly in both well-trained players and begunners.
3) After contraction of muscle biceps brachii with elbow flexion in a sitting position discharges of action potential of left and right muscle sternocleidomastoids were 69±21 msec (mean±s. d.), and after contraction of muscle deltoid anterior portion with shoulder flexion in the same position discharges of action potential of left and right muscle sternocleidomastoids were 42±21 msec. The appearance of action potential of left and right muscle sternocleidomastoids were observed in all of the subjects of the study. After contraction of muscle triceps brachii with elbow extension in the sitting position discharges of action potential of left and right muscle splenius were 82±18 msec in four out of eight subjects, and after contraction of muscle deltoid posterior portion with shoulder extension in the same position, discharges of action potential of muscle splenius were 70±20 msec in five out of eight subjects. Splenius muscle activity was possibly absent in the well-trained as compared to the beginers.
4) The present experiments indicated that the junior high school students could learn to perform the ukemi safely sooner if taught to do it in the pull-type ukemi than if instructed in the more traditional way to keep their eyes on their belt-knots when falling.