Yoga claims many health benefits, most of which are anecdotal, the collected stories and somatic truths of its millions of practitioners. A few claims are solidly supported by research – like improvements in pain, reduction in inflammation, enhanced body awareness, and those work horses of yoga – better strength and flexibility. Yoga’s promising effect on other diseases and conditions, like cancer, diabetes, and heart disease, are seeing a greater number of quality studies. But one thing for certain is that releasing toxins through sweating or twisting asanas is pure myth.
What is Sweat?
Sweat is 99% water with a dash of essential salt minerals, urea and other wastes from protein metabolism, and some trace elements like zinc. Sweat’s main job is thermoregulation – to cool the body. When your internal temperature rises, your sweat glands secrete a non-toxic mix of mostly water to your skin’s surface, where heat is removed by evaporation – aka sweat. When you sweat in yoga class, you are not releasing alcohol, angst, toxic chemicals, drugs, illness or supersized happybad meals – you are secreting mostly water for the physiological purpose of cooling your body. If you are hoping to rid yourself of the aforementioned toxic brew, rest assured that the actual parts of your body that do this work – your liver, kidneys, colon and mind – are actually doing this work. Unless…and this is a big unless, you have been occupationally exposed to high levels of heavy metals – arsenic, cadmium, lead, mercury, etc. A 2012 review that looked at 24 studies on toxicants and sweat, found levels of heavy metals in the sweat of subjects who had been occupationally or geochemically exposed. For the typical Western yoga practitioner, who has not had an occupational exposure, has not been exposed via geochemistry, and is not in kidney failure, the science has simply not shown sweat to be a major route for ridding the body of unwanted toxins.
Sweating is not a case of more is better. Excess sweating means elimination of water and its associated weight – aka water weight, which is not a true loss of fat or mass. In an ironic turn of events, heavy sweating is associated with a significant diminishment of urinary output, thus concentrating uric acid and other cellular wastes in your blood – the buildup of which is toxic to your body.
What About Wringing Toxins Out Your Organs?
I often hear yoga teachers refer to the detoxifying effects of spinal twists. While there may be a metaphorical truth to this claim, it’s more nuanced and complex than that. Whether you are flexing, extending, or twisting your core muscles, the act of generating force in a muscle causes the smallest of blood vessels (arterioles and capillaries) to vasodilate (get bigger), which pulls oxygen rich blood out of the arteries (lowering arterial blood pressure) and into these tiny vessels, feeding the work of your cells. Your body’s waste removal system (lymphatic system) works in parallel with your cardiovascular system, thus while blood is being drawn into the muscles, cellular waste (toxins) is removed. This happens wherever and however you move your muscles and is not the territory of twists alone. Although a twist is an effective way to bring blood to your intervertebral discs, which do not have their own blood supply but rely on diffusion from the blood supply at their margins, flexing or extending your trunk may accomplish the same thing, as movement is thought to enhance the process of diffusion.
Now you see how using your muscles in yoga facilitates cellular waste removal and keeps your spinal discs nourished, but what about wringing stale blood and toxins out of your organs to allow fresh blood in? Well, I lean on the wit of Kim & Mel at Smarterbodies to eviscerate this myth. “So twist and do so knowing that you are helping create movement in your internal organs, but in NO WAY are they “wrung out.” That is not possible and if that happens to you or inside of you please go to a hospital, because you are going to die. Also, do the organs fill with fresh blood after a trunk rotation? No, they are CONSTANTLY filled with “fresh” (I’m assuming this means oxygenated) blood, because we have these vessels called ARTERIES whose job is to deliver this type of blood constantly from birth to death.”
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