What is a function of the hamstring muscles?

Hip flexion is performed by the iliopsoas and rectus femoris; the hamstrings are antagonists to this movement.

The hamstrings - comprising the biceps femoris, semitendinosus, and semimembranosus - cross both the hip and knee joints. At the hip, they produce extension by pulling the femur posteriorly, which is critical for movements like running and deadlifting. This dual-joint function makes them essential stabilizers and movers in most lower-body athletic patterns.

Plantar flexion is a function of the gastrocnemius and soleus muscles of the calf, not the hamstrings.

Knee extension is performed by the quadriceps group; the hamstrings perform knee flexion, the opposing action.