It is through gravity that people are able to fall on the ground without losing contact with it. Moreover, gravity makes it possible to move by lifting the body even when one is moving on a level surface. The braking action and gravity act together when one is moving. During this action, two different strategies of conserving energy are applied. First, there is the bouncing mechanism of running, up to the highest speed that can be attained. Secondly, there is the pendular walking mechanism, up to intermediate speeds. Therefore, in both mechanisms, there is a forward deceleration speed undergone by the body on every step. This happens because point where the foot meets the ground and the center of mass of the body are different.
The deceleration results in a loss of kinetic energy loss in the body. When making the running step, the center of mass lowers as it decelerates forward and increases during the forward acceleration. The reason why this happens is to allow changes in potential and kinetic energies at the center of body mass. This energy is absorbed and restored by tendons and body muscles. Contrary, when making the first walking step, the body’s center of mass lowers as it accelerates forward and rises when making forward deceleration. This ensures that kinetic energy being lost is transformed as potential energy increases. Consequently, mechanical energy in the body is conserved when walking through the conversion of kinetic energy into gravitational potential energy. This results in the recovery of kinetic energy from the potential energy.
