投球障害肩の危険因子としての筋疲労と関節位置覚低下 [in Japanese] Extremity Muscle Weakness and Sensorimotor System Acuity as Risk Factors of Throwing Shoulder Injury [in Japanese]
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An excessive number of pitches, disarrayed pitching forms and fatigue of shoulder muscles are known to be risk factors of shoulder disorders after pitching. Although the evidence of shoulder pain in throwing athlete is little, limiting the number of pitches and securing an appropriate interval is suggested for injury prevention. We evaluated the fatigue of shoulder muscles and the change of proprioception quantitatively in pitching. Eleven high-school pitchers were intended in a prospective study. A hand-held dynamometer was used to evaluate the peri-shoulder muscle strength bilaterally (dominant side: DS, non-dominant side: NDS) in 7 directions, and the shoulder joint proprioception was evaluated in 6 directions before and after pitching. Wilcoxon's signed rank test was used. The basic muscle strength before pitching was higher at DS except in the empty can test. There was a significant strength reduction in the empty can test, flexion and internal rotation at DS after pitching in comparison with NDS. There was a significant false recognition at abduction external rotation 30 degrees and 90 degrees after pitching on D. The reduced strength in the empty can test of D suggested a potential superior rotator cuff damage by pitching. The internal rotators were lead to fatigue by repetitive eccentric contraction at the late cocking phase and concentric contraction at acceleration. These differences in exhaustion of the internal and external rotators influenced the sensors which lead to the misconception of the position sense. Individual regular examination of muscular strength and propriocepsion is considerable method to decide an appropriate pitching interval and number for a prevention of throwing shoulder injury.
Katakansetsu 34(3), 873-877, 2010-08-04
Japan Shoulder Society