As mentioned above physics can de applied to not only physical therapy but kinesiology, physiology and biomechanics as well since torque and other forces apply to the body bending, stretching and even moving. The body can be interpreted as a system of pulleys and levers and each exercise is designed for each part of the body keeping in mind the influence of natural forces that are acting on the patient’s body. The levers of the body are the elbow and the bones attached to it on either side or the hands as a first-class lever, as a second-class lever, the foot since the load would be between the force and the fulcrum, in this case the fulcrum are the antagonist and agonist muscles of the foot that are acting on the effort of walking. The load is completely put on the floor, and the floor has an equal and opposite reaction pushing against the foot, as Newton stated. As a third-class lever, the muscles of the arm bending can be considered. Next the leg and foot muscles and connecting bones can be considered a pulley as well as the quadriceps, the patella and its tendons that are creating a pulley-like system while running, walking or vending the leg