Have you ever stood in a line, maybe for an elevator or a roller coaster, and you notice that the line is growing faster than people can move through? The line grows and grows until either: people don’t think the wait is worth it, or you run out of room, and the line becomes a disorganized crowd. That second scenario is similar to what happens in venous stasis, where blood in veins doesn’t move well enough, and like orderly lines devolving into chaotic masses, veins can become diseased and cause other problems later on (for more background on veins and vein problems, check out our previous article). This backup occurs more often with age, but fortunately there is a simple and effective way of preventing it.
Leg Muscles Help to Facilitate Venous Blood Flow
Most people know that your heart pumps your blood, but this is only true to a certain extent. Your heart pumps blood via the arteries from your lungs to your body’s tissues to help deliver oxygen, but due to intricacies in how fluids flow, it is less involved in pumping blood in veins. How then does blood in your veins get back to your heart? It’s a complex combination of forward positive driving pressures from your body muscles (like squeezing on a tube of toothpaste) and negative pulling pressures from breathing (like sucking on a straw).
A recent study has shown that breathing is the predominant driver of venous blood flow,¹ but many studies support that muscle contractions play a nontrivial role in pumping venous blood.²⁻³ In fact, one group of scientists tested the difference in blood flow by electrically stimulating the calf muscles of one leg while comparing it to resting muscles of another leg, and they found that the muscle contraction produced a blood flow increase of up to 47% in people on bed rest.⁴ So while your heart is almost entirely responsible in getting blood to your tissues, your muscles certainly fill a role as a sort of “peripheral heart” in getting blood back to your heart. And when it comes to your legs and preventing venous stasis, there is no muscle more important than your calf.⁵
The Calf Muscle Pump
Let’s go back to an analogy we used before: squeezing toothpaste out of a tube. Here, your blood is toothpaste, your veins are the tube, and your muscles are doing the squeezing. Squeezing from the middle of the tube is like contracting your thigh muscles. You will certainly get toothpaste moving forward, but you are also putting pressure backward. Fortunately, your calf muscles act by squeezing from the end of the tube, making sure that everything is moving forward in a beneficial and healthy way. This subtle function of your calf muscle is often referred to as the ‘calf muscle pump’ in medical terms, and keeping it active is an important part of preventing vein problems.⁶
So get out and walk. Take the stairs when you can. It’s not only healthy for your heart, but working your peripheral heart can help to keep your veins healthy too.
References
[1] Miller JD, P. D. (2005). Skeletal muscle pump versus respiratory muscle pump: modulation of venous return from the locomotor limb in humans. J Physiol (Lond), 563(Pt 3):925-43.
[2] HF, S. (1966). Muscle Pumping in the Dependent Leg. Circulation Research, 19:180-190.
[3] Shiotani I, S. H. (2002). Muscle pump-dependent self-perfusion mechanism in legs in normal subjects and patients with heart failure. J Appl Physiol, 92(4):1647-54.
[4] Broderick BJ, O. D. (2010). A pilot evaluation of a neuromuscular electrical stimulation (NMES) based methodology for the prevention of venous stasis during bed rest. Med Eng Phys, 32(4):349-55.
[5] Uhl JF, G. C. (2015). Anatomy of the veno-muscular pumps of the lower limb. Phlebology, 30(3):180-93.
[6] Foy White-Chu, E., & Conner-Kerr, T. A. (2014). Overview of guidelines for the prevention and treatment of venous leg ulcers: A US perspective. Journal of Multidisciplinary Healthcare, 7, 111–117.
