A shoulder-wheel is used in one of the therapeutic exercises for shoulder joint disease, but there are few practical studies about the actual method and the time that is clinically important in using a shoulder-wheel. Therefore, the subject of exercise with the shoulder-wheel is difficult to decide on and to prescribe. The purpose of this study is to analyze the characteristic activity of the shoulder muscles (Trapezius-upper, Deltoid-anterior and middle, Infra spinatus), and trunk muscles (Internus-Externus obliques abdominis, Multifidus), so that healthy subjects and the patient with a scapula fracture use the shoulder-wheel for exercising in different directions. The shoulder muscle activity in the abducted direction in the healthy subjects gradually increases to the peak activity on the elevation phase. The activity of the trunk muscle of exercise side increases on the depression phase. After that, the activity of trunk muscle displaces to opposite side smoothly. On the other hand, the activity of the shoulder muscle on the elevation phase in the adducted direction rapidly increased compared with another direction. And the trunk muscles act on markedly on the elevation phase. In the patient, a pattern of muscle activity was similar to a healthy subject, except for deltoid, infra spinatus and multifidus on the elevation phase in the abducted direction. A shoulder-wheel is often used in individual training, but it causes a secondary trouble when going on the exercise of a different muscle active pattern.
