Purpose: The purpose of this study is to compare the flexibility of high school baseball players’ LBP Group and bilateral lower extremity muscles. Method: This study conducted a questionnaire survey and measurement of muscle flexibility targeting 23 high school baseball players in Korea. The questionnaire consisted of 7 items on basic information and 4 items on past and present back pain, and muscle flexibility measurement (Tomas test, Hip extension, HBD, SLR, Trunk rotation) tests were conducted. As for the data processing of this study, the mean and standard deviation of all questions were calculated by using the SPSS 26.0 package. The two-way ANOVA was performed to examine the effect of each measurement according to the LBP Group (LBP; presence or absence) × both sides (dominant, non-dominant), and if an interaction was found, the post hoc test was conducted. The independent sample t-test and paired t-test were performed for the post hoc verification. The statistical significance level was based on p<.05. Results: As a result of the Thomas test conducted for the LBP Group and both sides of the lower extremity mus-cle flexibility, the both sides of the main effect turned out to be significant [F(1,21)=4.905, p<.05]. In the case of the hip extension, the main effect of both sides turned out to be significant [F(1,21)=6.768, p<.05], and the main effect of the LBP Group also turned out to be significant [F[(1,21)=5.065, p<.05]. Furthermore, in the case of the SLR, the main effect of the LBP Group turned out to be significant [F(1,21)=5.395, p<.05]. Conclusion: Gathering the results above, as a cause of the LBP among the high school baseball players, there is a possibility that a decrease in flexibility due to hip flexion and extensor tension may be induced, and hence, the possibility of inducing LBP was confirmed due to the excessive use of the back muscles of the accelerator dur-ing the pitching and hitting sections. In the future studies, it is necessary to develop and apply the programs which can prevent and rehabilitate the LBP.
2. Research Method