[The activity of muscles of the shoulder girdle and shoulder during the constant isometric efforts of the wrist].

Abstract

Electromyogramms (EMG) of eight muscles of the arm were analyzed in 11 healthy men aged 25-40 years during equal magnitude isometric efforts created by wrist. Subjects had to track cursor that moved around on the screen at a constant speed (16 degrees/s) in a horizontal plane. Thus, the subject slowly changed the direction of generation of efforts, while its amplitude remained constant. It was established that during creation of the static efforts equal in all directions, the extensors activity was mainly in the areas of extension of shoulder and elbow joints, whereas the flexor activity was observed in all directions with maximum, which corresponded to the arm bending. It is assumed that muscular activity is organized on the principle of the synergies that are clearly related to the task and beyond it can not exist.