The Effect of Step Frequency and Running Speed on the Coordination of the Pelvis and Thigh Segments During Running.

This study investigates the specific influence of step frequency (SF) and speed on the coordination between pelvic and thigh movements. Eight recreational male runners ran at different SFs and speeds on an instrumented treadmill. The coordination between the pelvis and thigh segments was analyzed using modified vector coding in the sagittal and frontal planes (FPs). Our findings show that hip range of motion increases as a function of SF in the sagittal plane. Pelvic tilt plays a compensatory role in hip extension, particularly at lower SFs. In the FP, pelvic roll increased at lower SFs, whereas the thigh abduction angle was participant dependant. Coordination analysis showed that thigh movements dominated the sagittal plane motion, which was simplified at higher SF. At low SF, the pelvic movements were increased and anticipated, playing a more dominant role in explaining motion. In the FP, pelvic movements dominated the motion. The increase in pelvic motion at low SFs stretches the hip flexors further and for a longer period. The link between SF, pelvic motion, and the risks of running-related injuries in the sagittal and FP is considered. Understanding these could help athletes and sports professionals optimize performance and reduce injury risk.