Association between low back pain and limited lower-extremity flexibility in elementary school-aged softball players: a cross-sectional study.

Background: Limited lower-extremity flexibility has long been debated as a physical risk factor contributing to low back pain in various populations. However, its impact on younger populations, particularly elementary school-aged softball players, remains unclear. This study aimed to explore the relationship between limited lower-extremity flexibility (iliopsoas, hamstrings, and quadriceps femoris) and low back pain in elementary school-aged softball players.

Methods: This cross-sectional study included 521 elementary school-aged softball players (469 males and 52 females; mean age, 10.7 years) who participated in annual medical evaluations from 2017 to 2019. Lower-extremity flexibility was assessed once during annual medical evaluations using the Thomas test for the iliopsoas, straight-leg-raise test for the hamstrings, and heel-to-buttock-distance test for the quadriceps. Additionally, low back pain during the previous season was evaluated through self-administered questionnaires distributed to participants and collected during medical check-ups. The prevalence of low back pain and its association with lower-extremity flexibility were investigated using univariate and multivariable analyses. In multivariable analysis, age, position, body mass index, and total practice time per week were included as explanatory factors.

Results: Overall, 16.9% (88/521) of the players experienced low back pain that required rest during the previous year. After adjustment for confounding factors (age, position, body mass index, and total practice time per week) with a logistic regression model, low back pain showed a significant association with quadriceps muscle tightness (odds ratio: 3.15, 95% confidence interval: 1.51-6.56, P = .002).

Conclusion: Quadriceps femoris tightness may be a significant risk factor for low back pain in elementary school-aged softball players. These findings underscore the importance of assessing quadriceps femoris tightness to prevent low back pain in elementary school-aged softball players.

Trial registrations: Not applicable.