The period of the leg can be approximated by treating the leg as a physical pendulum, with a period of Equation representing the period of oscillation for a pendulum, where I is the moment of inertia, m is the mass, and h is the distance from the pivot point to the center of mass. The leg can be considered to be a right cylinder of constant density. For a man, the leg constitutes 16 \% of his total mass and 48 \% of his total height [21]. Find the period of the leg of a man who is 1.83 m in height with a mass of 67 kg. The moment of inertia of a cylinder rotating about a perpendicular axis at one end is ml2/3. sec The pace of normal walking (3.0 mi/hr) is close to the natural frequency of the leg because the most efficient frequency to "drive" a system is the natural frequency. It takes less effort to walk at this rate.