What is an action of the hamstring muscles?

Hip flexion is performed by the iliopsoas, rectus femoris, and tensor fasciae latae, not the hamstrings, which are anatomically positioned to extend the hip.

The hamstrings - biceps femoris, semitendinosus, and semimembranosus - originate on the ischial tuberosity of the pelvis and cross both the hip and knee joints. Their proximal action is hip extension, which they produce by pulling the femur posteriorly relative to the pelvis. This is why they are active during movements like deadlifts and running push-off phases.

Plantar flexion is produced by the gastrocnemius and soleus muscles of the posterior lower leg, not the hamstrings.

Knee extension is the action of the quadriceps muscle group; the hamstrings perform the opposing action of knee flexion.