ISOKINETIC EVALUATION OF SHOULDER INTERNAL AND EXTERNAL ROTATORS STRENGTH AND ENDURANCE IN FOUR LEVELS OFSCHOOL-AGED BASEBALL PLAYERS

The purpose of this study was to compare strength and endurance differences in shoulder external and internal rotation torque ratios among four levels of school-aged baseball players, The subjects (N=97) were assessed the strength and endurance strength of shoulder internal and external rotation muscles with Kin Com dynamometer. The functional scapular plane of shoulder movement was used as the testing position, Strength development of IR and ER generally varied with school-aged increased, Comparing with adult pitchers, adolescence and pre-adolescence baseball pitchers had relatively weak shoulder external rotation muscles, especially after high repetition muscle contraction. In order to prevent shoulder injury in adolescence and pre-adolescence baseball throwers, muscle endurance in shoulder external rotators must be emphasized