What is the function of the Calf in blood circulation? The nickname (second heart) given to the Calf is based on its function of assisting VENOUS RETURN. While the main heart pumps oxygenated blood throughout the body, the Calf plays a VITAL role in PUSHING blood back to the heart in addition to assisting in locomotion, as well as balance and body posture! ❤️💪🏻😛