Hamstrings are active for stabilization of the knee joint and as a hip extensor. Accelerating the foot down while in flight and moving the body in front of the foot while in support are both actions which the hamstring is largely responsible for.
Quads definitely play an important role in sprinting though…they help you to fight the effect of gravity pulling you down towards the ground. They are very important in maintaining leg stiffness in top end speed running.
ELITETRACK Founder