Walking uses an energy cycle that is like a pendulum's motion.
Unlike running, which relies on storing elastic potential energy,
walking involves gravitational potential energy. When we step
forward, our body falls slightly, converting some of our gravitational
potential energy into motion as kinetic energy. As our weight
shifts to a position over the foot we've just put down, the body
moves upward slightly, converting the kinetic energy back into
gravitational potential energy. Our motion in walking is like
a pendulum's motion, but a person behaves like an upside-down
pendulum, with each foot acting as a pivot point and the body
as the pendulum weight. Just as a longer pendulum will take longer
to complete one cycle of motion, so the time for a complete cycle
of walking will be greater for a person with longer legs.