Knickerbocker's theory emphasizes on the interdependence of major players in the same industry. Imitation is the name of the game where firms try to match each other's moves to keep each other in check so as not to allow a rival gain a competitive advantage over others.
hamstrings. extend the hip and flex the knee against resistance and are important knee stabilizers. help control hip flexion in weightbearing position by contracting eccentrically when the flexion occurs in same direction as gravity as dead lift or hip=hinge position.
Rectus Femoris (a large quad but also hip flexor muscle) Iliopsoas is your strongest hip flexor, though often divided up into iliacus and psoas as separate muscles, they have the same insertion point on the femur. Sartorius is the longest muscle in your body and serves quite a few functions.