Which action best describes the hamstrings' dual role during late recovery in sprinting?

• A. Simultaneous concentric hip extension and knee flexion
• B. Eccentric hip extension and knee flexion
• C. Concentric knee extension and hip flexion
• D. Isometric hip extension and knee flexion

Answer: (A)

Biarticular hamstrings cross both the hip and the knee, so they can shorten across two joints at the same time. In late recovery of sprinting, they actively shorten at the hip to extend the thigh backward and at the knee to flex the knee. This combination pulls the leg into a compact, rapid swing, helping position the foot for a quick transition to ground contact and supporting fast leg turnover. The action aligns with how the hamstrings function during this phase: two joints, one coordinated shortening, delivering both hip extension and knee flexion simultaneously.