Vein muscle pump
The heart serves as a pump through which up to 7,000 l of blood circulate daily towards the arteries. The same volume of blood has to be returned to the heart by veins. Considering the upright human posture, there are several factors needed for blood to overcome gravity and reach the heart.
The muscles of the lower leg function as a pump with a vital function of returning blood to the heart. Since all blood in legs makes the largest distance, this muscle pump is crucial for pushing blood towards the heart.
How does the vein muscle pump work?
Leg movement activates the lower leg muscles. The muscle contracts and presses the veins between the muscles and squeezes them. There is less space in the veins for blood, so it is pushed towards the heart.
The venous valves open under pressure and let blood flow. When the muscles are relaxed, the pressure of blood flowing towards the heart decreases and the venous valves close, preventing the backflow of blood into legs.
The number of venous valves varies depending on the vein length, between 2 and 20.