Lower Extremity Kinematic and Kinetic Adaptations During a Half Marathon

This study aimed to clarify the biomechanical adaptations recreational runners experience during a half marathon. Thirty‐seven healthy runners completed a half marathon as fast as possible on a laboratory‐instrumented treadmill. Kinematic and kinetic data were collected every 5 km from 0 to 20 km. As mileage accumulated, peak vertical ground reaction force (GRF) decreased from 5 km onward ( p < 0.005) and impulse declined from 10 km ( p < 0.05). Ground contact time increased from 10 km ( p < 0.05). Joint‐level adaptations included an increased hip extension moment ( p < 0.005) and hip adduction angle from 10 km ( p < 0.05), decreased knee abduction moment from 5 km ( p < 0.005), and greater knee flexion angle at 10 km ( p < 0.001) and 15 km ( p = 0.031). Additionally, the symmetry angle of peak vertical GRF decreased at 20 km, suggesting improved interlimb symmetry under fatigue. These findings provide insight into fatigue‐related biomechanical adaptations during long‐distance running. Further research is needed to clarify how these changes relate to injury development.