Spring Mechanisms in the Foot and Lower Extremity In this 18-minute mini-lecture, I review how the spring mechanisms within the foot and lower extremity are vital to optimizing the biomechanics of weightbearing activities. The mechanics of Hooke's Law is reviewed along with the concepts of spring stiffness and viscoelasticity. In addition, I discuss how elastic strain energy is used within the muscle, tendons and ligaments of running, galloping, and hopping animals to store and then release ener