Does preferred technique influence how kinematics change during a run to exhaustion?-A cluster based approach

Fatigue-related changes in running technique may depend on a runner's preferred style. Understanding these changes can inform targeted training to enhance performance. In previous work, we identified two technique-based clusters of runners: the "neutral pelvis" and the "tilted pelvis" clusters. This follow-up study examined whether fatigue induces cluster-specific technique adaptations. Sixty runners (neutral pelvis, n = 32; tilted pelvis, n = 28) completed a treadmill run to exhaustion at 5% above their individual lactate threshold speed. Stride frequency, duty factor, trunk and lower limb kinematics were compared between clusters at the start, middle, and end of the run using a 2-way repeated measures analysis of variance (ANOVA). All runners reached exhaustion in ∼20 minutes, covering ∼5 km. Runners from the tilted pelvis cluster consistently showed greater trunk-to-pelvis extension, more pelvic anterior tilt and greater hip flexion, and a smaller duty factor compared with the neutral pelvis cluster throughout the run. Fatigue-related adaptations were similar across clusters: reduced stride frequency, increased duty factor, greater trunk flexion during stance, increased plantar flexion, and higher coordination variability (trunk-to-pelvis-hip, hip-knee, knee-ankle) during swing. Although fatigue affected both groups similarly, the underlying technique differences suggest these adaptations may have distinct mechanical or performance consequences. Understanding such cluster-specific responses can help coaches tailor training and fatigue management strategies to individual running styles.