If you type “yoga and lymphatic drainage” into any search engine, you will come across hundreds of articles confidently stating that yoga improves the functioning of the lymphatic system. Searching deeper to find evidence that backs up this claim proves much more challenging.

The lymphatic system has been somewhat neglected in the past by both the scientific and medical communities because of its vagueness in structure and function. The amount of available information on this fascinating system is scarce, particularly compared to such systems as the cardiovascular system, but it is no less significant than any other bodily system.

The lymphatic system is a linear, one-way system of vessels, cells, and organs that runs parallel to and entwines the blood circulatory system. It carries excess fluids from the tissues of the body to the bloodstream and plays an integral role in the immune functions of the body. It also plays an important role in the process of inflammation and is involved in the transport of dietary fats and fat-soluble vitamins absorbed in the gut.

The leakage of plasma from the capillaries of the cardiovascular system creates interstitial fluid that bathes the surrounding cells, supplying them with nutrients and oxygen and collecting carbon dioxide and other waste products. It has been estimated that the total plasma volume of the human body (approximately three liters) leaks from the blood circulation every nine hours, and while some interstitial fluid is reabsorbed directly by the blood vessels, the majority of this fluid is transported back to systemic circulation through the lymphatic system (Levick and Michel 2010). Once the interstitial fluid enters the lymphatic system, it becomes lymph.

Unlike blood, lymph does not have a pump like the heart to help keep it circulating, although the presence of one-way valves within the lymph vessels does prevent backflow of lymph. These one-way valves are located close to one another, and each one causes a bulge in the lymphatic vessel, giving the vessels a beaded appearance.

Since the late 1900s, knowledge about the physiology of the lymphatic system has grown more complete. However, there is still no generally accepted model that adequately describes the mechanisms and regulation of lymph transport. Lymph flow is likely to be the result of a complex combination of both active and passive driving forces.

The intrinsic driving force, known as the active pump, is created by a lymphangion, which is the section of a lymphatic vessel between two adjacent lymphatic valves (Gashev and Zawieja 2001). Lymphangions act like the ventricles of the heart.

Coordinated contractions of these sections are initiated by the pacemaker activity of smooth muscle cells and modulated by the pressure gradient across the vessel wall (Gashev 2002). It is important to note that our precise understanding of this process is somewhat limited, although it is believed that the contractions spread from one lymphangion to the next like a wave that causes contraction along both the length and width of the vessels (Margaris and Black 2012). The contractions can be compared to the rhythmical contraction of the digestive system, known as peristalsis.

Extrinsic driving forces, known as the passive pump, include lymph formation, arterial pulsations, skeletal muscle contractions, fluctuations of central venous pressure, gastrointestinal peristalsis, and respiration. These forces produce passive hydrostatic gradients in the lymphatic network, which may effectively propel lymph (Gashev 2002). It is not clear whether extrinsic mechanisms can have a significant or even dominant role in the pumping of lymph. Engeset and colleagues (1977) suggested that, at rest, approximately one-third of lymph transport in the lower extremities results from compression by skeletal muscle contractions and two-thirds results from the active pumping of the collecting vessel network.

Exercise is thought to help increase lymph flow via muscle contraction around the lymphatics (Cheville et al. 2003). External forces such as massage have been shown to affect the filling of lymphatic capillaries rather than the pumping of the larger lymphatic vessels (Auckland 2005).

Like other bodily systems, the lymphatic system is under the control of the nervous and endocrine systems, matching lymphatic pumping to the physiological activities of other parts of the body.

As mentioned above, there is a scarcity of scientific and medical information about the lymphatic system in general, and information about this system specifically related to yoga or breathing is even more scarce. While there is certainty about the impact of the phases of respiration on venous return, there is a great deal of uncertainty and many differing opinions about its impact on the lymphatic system (Piller et al. 2006). The same applies for the role that inverting the body in poses like Shoulder Stand and Headstand plays on the lymphatic system. Some sources (Cemal, Pusic, and Mehrara 2011; Seki 1979) discuss how postural changes may affect the flow of lymph. However, while common sense tells us that inverting the body is likely to have some effect on improving lymphatic drainage, it is important to note that for most of us, our lymphatic system is already working very effectively and does not need to be improved.

Join one of my upcoming live workshops:

References:

Auckland, K. 2005. “Arnold Heller and the Lymph Pump.” Acta Physiologica Scandinavica 185:171-180.

Cemal, Y., A. Pusic, and B. Mehrara. 2011. “Preventative Measures for Lymphedema: Separating Fact From Fiction.” Journal of the American College of Surgeons 213 (4): 543-551.

Cheville, A., C. McGarvey, J. Petrek, S. Russo, M. Taylor, and S. Thiadens. 2003. “Lymphedema Management.” Seminars in Radiation Oncology 13:290-301.

Engeset, A., W. Olszewski, P. Jaeger, J. Sokolowski, and L. Theodorsen. 1977. “Twenty‐Four Hour Variation in Flow and Composition of Leg Lymph in Normal Men.” Acta Physiologica Scandinavica 99: 140-148.

Gashev, A. 2002. “Physiologic Aspects of Lymphatic Contractile Function.” Annals of the New York Academy of Sciences 979: 178-187.

Gashev, A., and D. Zawieja, 2001. “Physiology of Human Lymphatic Contractility: A Historical Perspective.” Lymphology 34 (3): 124‐134.

Levick, J., and C. Michel. 2010. “Microvascular Fluid Exchange and the Revised Starling Principle.” Cardiovascular Research 87:198-210.

Margaris, K., and R. Black. 2012. “Modelling the Lymphatic System: Challenges and Opportunities.” Journal of Royal Society Interface 9:601-612.

Piller, N., G. Craig, A. Leduc, and T. Ryan. 2006. “Does Breathing Have an Influence on Lymphatic Drainage?” Journal of Lymphoedema 1 (1): 86-88.

Seki, H. 1979. “Lymph Flow in Human Leg.” Lymphology 12:2-3.