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

Two technique-based clusters of runners were identified, with the tilted pelvis cluster consistently showing greater trunk-to-pelvis extension, more pelvic anterior tilt, greater hip flexion, and a smaller duty factor compared to the neutral pelvis cluster throughout the run.

• Sixty runners were studied: neutral pelvis cluster (n=32) and tilted pelvis cluster (n=28).
• Differences between clusters were maintained throughout the entire run (start, middle, and end).
• The tilted pelvis cluster showed greater trunk-to-pelvis extension, more pelvic anterior tilt, and greater hip flexion.
• The tilted pelvis cluster also showed a smaller duty factor compared to the neutral pelvis cluster.

All runners reached exhaustion in approximately 20 minutes, covering approximately 5 km, during a treadmill run at 5% above their individual lactate threshold speed.

• The run-to-exhaustion protocol was conducted on a treadmill.
• Speed was set at 5% above each runner's individual lactate threshold speed.
• All 60 runners reached exhaustion in approximately 20 minutes.
• Runners covered approximately 5 km before exhaustion.

Fatigue-related adaptations in running technique were similar across both clusters, including reduced stride frequency, increased duty factor, and greater trunk flexion during stance.

• Both the neutral pelvis and tilted pelvis clusters showed reduced stride frequency with fatigue.
• Both clusters showed increased duty factor as fatigue progressed.
• Greater trunk flexion during stance was observed in both clusters as fatigue developed.
• Increased plantar flexion was also observed in both clusters with fatigue.

Coordination variability increased with fatigue in both clusters for trunk-to-pelvis-hip, hip-knee, and knee-ankle joint couplings during the swing phase.

• Higher coordination variability was observed for trunk-to-pelvis-hip coupling during swing.
• Higher coordination variability was observed for hip-knee coupling during swing.
• Higher coordination variability was observed for knee-ankle coupling during swing.
• These increases in coordination variability occurred similarly in both the neutral pelvis and tilted pelvis clusters.

The study used a 2-way repeated measures ANOVA to compare stride frequency, duty factor, trunk and lower limb kinematics between clusters at the start, middle, and end of the run.

• A 2-way repeated measures analysis of variance (ANOVA) was used as the primary statistical approach.
• Measurements were taken at three time points: start, middle, and end of the run.
• Variables assessed included stride frequency, duty factor, trunk and lower limb kinematics.
• This was described as a follow-up study to previous work that identified the two technique-based clusters.

Despite similar fatigue-related adaptations across clusters, the underlying technique differences between clusters suggest these adaptations may have distinct mechanical or performance consequences.

• Although fatigue affected both groups similarly in terms of kinematic changes, the authors noted that baseline technique differences could lead to distinct mechanical consequences.
• The authors suggest that understanding cluster-specific responses can help coaches tailor training and fatigue management strategies to individual running styles.
• The persistent between-cluster differences in pelvic tilt, trunk-to-pelvis extension, hip flexion, and duty factor were maintained throughout the exhaustive run.