Physiology of Yoga

Many come to yoga after an indulgent weekend (or week, or year) as a way to detoxify the body. Studios even advertise classes specifically designed for this purpose, such as “Weekend Detox Flow.” Hot yoga has gained popularity for many reasons, one of the biggest of which is because it is seen as a way to sweat out impurities from the body. But how exactly does yoga aid in the detoxification process? Do you still need to detox if you have been practicing healthy habits? Does yoga really make that much of a difference, or can we choose another activity to “sweat it out?” While other forms of exercise have the ability to provide detoxification, yoga incorporates specific practices that target several of the body’s systems to restore more harmonious circulation throughout the body.

One of the detoxification systems most impacted by yoga is the lymphatic system. Sometimes known as the second
circulation, the lymphatic system is a series of vessels that runs throughout the entire body, exchanging fluid with the blood vessels (arteries, capillaries, and veins) through the interstitial fluid between the cells of tissues. The blood vessels and lymphatic vessels can be visualized as two semi-parallel circuits that run throughout the body, interacting at specific points in capillary beds. The fluid inside the lymphatic vessels (the lymph) is boosted and cleaned at specific sites in the lymphatic system, known as lymph nodes (located in areas such as the armpits, groin, and neck). These nodes contain a high concentration of immune cells that help destroy pathogens and break down waste. Unlike our circulatory system, which utilizes the heart as a pump to maintain continuous blood flow, the lymphatic system does not have a central pump. Instead, it relies on periodic muscular contraction, hydrostatic pressure (pressure differences created by fluid imbalances), and movement to encourage lymphatic flow. Because of this design, yoga can be very beneficial, acting as a pump for the lymphatic system. Postures like inversions can help return lymph from the legs to the central body; postures that require heart opening can open up movement around the lymph nodes of the armpit and neck; and postures such as garudasana (eagle) and ardha kapotasana (pigeon) induce hydrostatic pressure changes in the groin (and armpit, in the case of garudasana), encouraging a surge of lymph flow following the release of the pose.

Yoga also aids in the detoxification process by changing the structure of the fascia. Specifically, Yin yoga aids in this type of detoxification. As discussed in a previous post, our lifestyle patterns (both sedentary and active) can induce structural and chemical changes in the fascia, resulting in fascia that becomes shortened and excessively cross-linked. Within this matrix, metabolic wastes can become trapped in the fibrous cells of the connective tissue, creating a dam against the free flow of nutrients and waste. When we practice Yin yoga, we begin to break down that dam, allowing waste from the surrounding muscle to exit, and fresh nutrients to flow in. Unhindered flow is important for everyone, but especially for those with an active yang practice. During exercise, waste such as lactic acid and harmful free radicals can build up. If we do not take the necessary time to release the fascia surrounding the muscles that were just worked, all of the waste from exercise will not be properly cleared. Acutely, this type of build-up can lead to minor problems like muscle soreness. Chronically, the build up of free radicals can have severe damaging effects on cells and can even ultimately lead to disease.

The digestive system is probably the most obviously affected detoxification system in yoga. Besides the effects of deep breathing on digestion (which will be discussed in a future post), certain yoga postures are structured to help promote the digestive process. Most twisting postures provide a gentle “wringing out” of the digestive organs by placing gentle pressure on the small intestine and colon. Postures such as pavanamuktasana and apanasana (the aptly named wind removing pose) provide a similar stimulation and can be utilized most effectively when practiced in an order that follows natural digestion. Since the natural flow of the colon starts at the lower right abdomen, ascends up the right side of the body, crosses horizontally to the left side of the body, and then descends down the left side of the body, these postures should be practiced from right to left (pavanamuktasana on the right, apanasana then pavanamuktasana on the left).

While yoga has many detoxification properties, an important thing to note is what is not actually happening in some postures. A simple Google search for “yoga detox” will yield countless articles claiming a myriad of benefits, none of which are based on how physiological processes occur. One such claim commonly voiced during twisting postures is that twists will massage the liver, helping to boost the body’s natural detoxification system. While the liver is responsible for cleaning the blood of impurities, there is no evidence that mechanical pressure on the liver induces such changes. While yoga and other types of exercise can increase blood flow, which can help speed up the liver’s filtering process, claims that massaging the liver (or other visceral organs, such as the spleen or gallbladder) will help cleanse the body are unfounded. Practices that increase heart rate and blood flow will aid in detoxification on a far greater scale.

So what does all of this mean on a personal level? Should we rely on yoga to help detoxify the body? Yes and no. Certain yoga practices can help boost the body’s natural detoxification systems, such as the lymphatic and digestive system. Yin-style practices can help release metabolic byproducts and waste, which can become trapped in the fascia. These types of practices are beneficial for everyone, whether you have been eating clean, nutritious foods or you are coming off a weekend of debauchery. However, other types of cardiovascular exercise that increase heart rate and blood flow should not be forgotten. These types of practices have the ability to induce changes that a yoga practice cannot. To detoxify the physical body, the best bet is to incorporate several styles of yoga, as well as regular cardiovascular exercise. As in all aspects of life, everything comes down to balance. Lightness and stability in the physical body are cultivated through grounding and balancing all of the physiological systems.