Changes in hip and spine movement with increasing running speed.

[Purpose] We aimed to clarify and compare the changes in thoracic and lumbar spine motion and to elucidate the relationship between hip and lumbar spine motion during running. [Participants and Methods] Seven healthy females were recruited in this study. Hip and spine movement were measured using a 3D motion analysis system when running at 6, 9, and 12 km/h. One-way analysis of variance was used to compare the changes in hip joint and spine angles during running. Correlation coefficient analysis was used to determine the relationship between the hip and lumbar spine angles at right and left toe-offs. [Results] As the running speed increased, the rotation angles of the thoracic and lumbar spine and the extension angles of the lumbar spine and hip joint significantly increased in the late stance phase. Significant positive relationships were observed between hip flexion and lumbar spine extension angles at toe-off when running at 6 and 9 km/h but not when running at 12 km/h. [Conclusion] To increase the running speed, participants increased the rotation angle of spine and the extension angles of the hip joint and lumbar spine during the stance phase. Participants extended the lumbar spine to compensate for the restricted hip motion at toe-off, which could cause stress to the lumbar spine.