Body Characteristics of Professional Japanese Keirin Cyclists: Flexibility, Pelvic Tilt, and Muscle Strength

OBJECTIVE: To identify muscle imbalances and pelvic tilt with implications for low back pain in Keirin cyclists. METHODS: We enrolled 16 Keirin cyclists (mean age, 32.2 ± 8.6 years) and 16 college students as controls (24.3 ± 2.3 years). We measured pelvic tilt, heel-buttock distance (HBD), iliopsoas flexibility (using the Thomas test), hamstring flexibility (using the straight-leg-raise [SLR] test), finger floor distance (FFD), and isometric and isokinetic hamstring and quadriceps muscle strength. These parameters were compared between the two groups, as well as between the right and left sides, by using the Mann-Whitney U test or unpaired t test. RESULTS: The results of this study revealed a significant anterior pelvic tilt at standing position and significantly higher HBD, SLR, and FFD in the Keirin cyclists than in the controls. The isokinetic muscle strength of the quadriceps and hamstring, and the hamstring-to-quadriceps ratio at high angular velocity were significantly greater in the Keirin cyclists. No significant differences were found between the right and left sides. CONCLUSION: This study revealed that the Keirin cyclists had an anterior pelvic tilt and imbalance in hip muscle flexibility, but the difference between the right and left sides were not significant.