Purpose: This study analyzed the effect of the isokinetic muscle function of the shoulder joint on the speed of a pitched baseball with 21 amateur club baseball players in their 20s in the D city area as subjects. Method: The subjects played the sport for between two years and seven years, have no pain or disease in their upper and lower limbs over the past year, and are divided into three groups: S1 for the maximum ball speed of 110 km/h or faster, S2 for 100 km/h or faster to slower than 110km/h, and S3 for slower than 100km/h in their pitched ball speed. The data for this study were processed using SPSS 18.0, calculating mean and standard deviations. One-way ANOVA was conducted to compare the differences between each item between the groups, and the Tukey method was used for follow-up analyses between the groups. In addition, multi linear regression was used to determine the effect of the isokinetic muscle function of the shoulder joint on the speed of a pitched baseball by angular velocity. The statistical significance level was set to p<.05. Results: The faster the pitching speed, the higher the statistical significance of the isokinetic muscle function of the shoulder joint (at an angular velocity of 60 degrees, 180 degrees, and 240 degrees). Among the isokinetic muscle function factors, it was shown that the extensor of the shoulder joint had a high explanatory power. Peak torque of right shoulder joint at 180 degrees angular velocity had 44.9%, and work per repetition at 240 degrees had 54.2% had 54.2% explanatory power. To sum up the above results, the better the muscle function the group has, the faster the speed of a pitched baseball, and especially extensor showed higher statistical significance than flexor. Conclusion: It was also shown that the isokinetic muscle function of the shoulder joint showed a stronger effect on the ball speed in extensor than in flexor of the right shoulder joint.
2. Research Method