During late flight, which action limits knee extension and stops before foot strike?

During late flight, which action limits knee extension and stops before foot strike?

• A. Eccentric knee flexion
• B. Concentric knee flexion
• C. Eccentric knee extension
• D. Isometric knee flexion

Answer: (A)

In late flight, the leg must be braked as it moves toward ground contact so the knee doesn’t fully extend before foot strike. This braking is provided by the knee flexors (hamstrings) contracting eccentrically. An eccentric knee flexion contraction lengthens the hamstrings under tension while controlling and slowing the knee’s extension, effectively stopping the knee from reaching full extension too early. If the knee were flexing concentrically, that would actively shorten the hamstrings to bend the knee further, not limit extension as you near contact. If the knee were extending eccentrically, the quadriceps would be acting as a brake to straighten the knee, which would promote extension rather than limit it. Isometric knee flexion would hold a position but wouldn’t actively regulate the speed or limit of extension as you approach foot strike.

In late flight, the leg must be braked as it moves toward ground contact so the knee doesn’t fully extend before foot strike. This braking is provided by the knee flexors (hamstrings) contracting eccentrically. An eccentric knee flexion contraction lengthens the hamstrings under tension while controlling and slowing the knee’s extension, effectively stopping the knee from reaching full extension too early.

If the knee were flexing concentrically, that would actively shorten the hamstrings to bend the knee further, not limit extension as you near contact. If the knee were extending eccentrically, the quadriceps would be acting as a brake to straighten the knee, which would promote extension rather than limit it. Isometric knee flexion would hold a position but wouldn’t actively regulate the speed or limit of extension as you approach foot strike.