13 minute read
The Physiology of Yoga
How research can help debunk common yoga myths
BY ANDREW MCGONIGLE Teaches anatomy and physiology in yoga teacher training courses internationally, and runs his own yoga anatomy online course, from Los Angeles, CA.
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There are many “old wives’ tales” that tend to spread like wildfire through the yoga community. Does practicing headstand stimulate the thyroid gland? Does twisting the abdomen help the liver detoxify? While not everything has to be evidence-based or quantified, I believe in the importance of trying to separate theory from fact, particularly when making bold claims about how yoga can improve our health or even help us to recover from illness and injury. Here, I examine three specific claims about yoga’s impact on our physiology using insights from scientific research.
MYTH OR FACT? HEAVY SWEATING DURING HOT YOGA DETOXES THE BODY
Detoxification is the physiological processes through which the body identifies, neutralizes, and eliminates toxic substances and metabolic byproducts. Detoxification is an essential part of homeostasis, and our bodies naturally possess the capacity to perform these processes very effectively. Without an effective detoxification system, we would be very unwell. ➝
Sweat glands are often perceived to play an important excretory function, similar to that of the kidneys. However, research has concluded that the role of the sweat glands in eliminating waste products and toxicants from the body seems to be minor compared with other avenues of breakdown (liver) and excretion (kidneys and gastrointestinal tract). Studies suggesting a larger role of sweat glands in clearing waste products or toxicants from the body (e.g., concentrations in sweat greater than that of blood) may be an artifact of methodological issues rather than evidence for selective transport. Nevertheless, studies have shown that perspiration plays a role in skin hydration and microbial defence.
So, it appears that heavy sweating in a hot yoga class or in a sauna might not help us to relinquish all those perceived toxins after all. However, the good news is that practicing yoga as part of a healthy lifestyle will allow our kidneys, liver, and gastrointestinal tracts to continue to work optimally.
MYTH OR FACT? YOGA INVERSIONS BRING MORE BLOOD TO THE BRAIN
There is widespread belief that inverting the body during asanas such as the headstand has many potential benefits from increasing blood flow to the brain to stimulating the pineal gland.
The brain has the very important ability to maintain relatively constant blood flow despite changes occurring elsewhere in the body. In healthy adults, large changes in blood pressure result in little or no change in cerebral blood flow. This mechanism of autoregulation of cerebral blood flow is vital since the brain is very sensitive to too much or too little blood flow. Only in severe head injury or acute ischemic stroke do we lose this autoregulation, leaving surviving brain tissue unprotected against the potentially harmful effect of blood pressure changes. So, it is reassuring to know that whether you regularly invert your body or not, your brain is receiving just the right amount of blood supply to meet its demands.
One physiological process that inverting the body can help with is venous return. Blood is easily pumped to our lower limbs from the heart via large arteries; however, returning blood to the heart is not such an easy process. The walls of the veins are considerably thinner, and their hollow passageways (lumens) are correspondingly larger in diameter compared to arteries, allowing more blood to flow with less vessel resistance. But by the time blood has passed through capillaries and entered venules and then veins, the pressure initially exerted on it by heart contractions has diminished significantly. While arteries can constrict quite dramatically, veins only stiffen. The venous system is also normally working against gravity to return blood from the lower limbs to the heart. Inverting the body causes a transient increase in venous return. Therefore, incorporating yoga asanas such as bridge pose or legs-up-the-wall into a yoga practice can have an impact on venous return.
MYTH OR FACT? YIN YOGA TARGETS THE FASCIA
It is commonly claimed that yin yoga works on the connective tissues of the body, particularly the fascia, the thin casing of connective tissue that surrounds and invests all muscles as well as every other organ, blood vessel, bone, and nerve fibre. But does yin yoga, wherein poses are often held for three to five minutes, really target the fascia?
Participants in a yin class are often asked to release all muscular tension and relax into the pull of gravity, whereas participants in a vinyasa class might be asked to co-contract antagonist muscles or core muscles. No matter what instruction is given, a stretch is a stretch—and a stretch is a tensile force on a muscle. When a tensile force is applied to a muscle, it is also applied to the surrounding fascia and invested muscle fibres and bundles. The muscle and fascia are so interwoven that you cannot choose which one you are stretching by contracting or not contracting certain other muscles.
It should be noted that as a stretch (or tensile force) is applied to tissues, they creep. Creep is the biomechanical term for the deformation of viscoelastic tissues. Once the tensile force is removed, tissues then recover and return to their original length, as long as they have not been elongated beyond their elastic capacity. One study looked at creep in the muscle–tendon unit of living humans during a 30-second stretch, finding that the greatest amount of creep was measured to occur within the first 15 to 20 seconds. Beyond that, to our knowledge, no studies exist on yoga poses and creep, which means we do not know the ideal duration for stretching tissues or how long tissues take to fully recover from their creep.
So, yes, yin yoga does affect the fascia of our bodies but not in isolation from muscles, and not any more than the same stretch performed in a different way (i.e., a more active way). Yin yoga, or any stretch held for three to five minutes, will affect the fascia, but the ideal frequency and duration remain a mystery.
Reproduced with permission from The Physiology of Yoga by Andrew McGonigle and Matthew Huy, 2021 Human Kinetics.
Plant-Based Pioneer
After discovering how a change in nutrition made him a better athlete, Brendan Brazier is now a leading authority on plant-based performance nutrition
BY LOUISE HODGSON-JONES SHIGGY ICHINOMIYA IMPACT guest editor, communications and event specialist in Victoria, B.C.
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Brendan Brazier always knew what he wanted in life. At home in North Vancouver, B.C. at age 15 he took up running so he could become a better hockey player. When he discovered he loved running he knew he wanted to run professionally and make a success of it. To do that he needed an edge. He started experimenting with his nutrition, realizing that a speedy recovery from a workout or race was the key ingredient in his training.
“I was looking for that advantage and became obsessed with my body to renew and regenerate myself as quickly as possible,” he recalls. “I tried different ways of eating; then I tried plant-based food, but I was always hungry.”
Over the years he kept experimenting, making many mistakes along the way, often relying on too many carbohydrates and not enough nutrients. Then he did some research on different plants, which back in the 1990s was a challenge as there wasn’t a lot of information available. But he did realize he was missing three essential nutrients—omega, calcium and iron.
“I started to make blender drinks. It was efficient and easy to digest and would fill me for hours.” He continued to experiment adding hemp, flax, pea and rice protein but he was constantly feeling tired with low energy. Then through a chance encounter with a Vancouver businessman, Charles Chang in 2003, he discovered maca, a root vegetable that has properties to aid adrenal fatigue. He immediately noticed a difference.
Brazier and Chang collaborated on the ingredients, producing a plant-based drink powder and in 2004, Vega the multi-million-dollar company was founded. “Vega was marketed to busy people who wanted to feel good, and not necessarily to vegans,” Brazier said. The product was an instant success and when they sold the company in 2015 it was bought for $500 million U.S. ➝
Brazier, 47, was a track runner in school and loved running the trails near his home in North Van’s Lynn Valley. Seeing more opportunities to race professionally, he became a triathlete, which he did for seven years, making enough to live on but not reaching the top tier. But he is fine with that. “I was never competitive, I competed because I enjoyed it and wasn’t there to win.” He entered his first Ironman in 1998 in Penticton and regularly competed there until 2004. His love of trail running saw him take two Canadian 50-kilometre Ultramarathon titles—in Victoria, B.C. in 2003 and in Toronto, ON in 2006.
During that time he helped some of his NHL and NFL athlete friends with their nutrition, not intending to make a career out of it but just to help them perform better. “It was very casual. I would help them with tips if they asked.”
During his sports career he would spend hours writing his recipes; he accumulated over 1,000 he says. “I would go back to them and see what I ate for a particular race and if it worked I would use it again.” His diet switched from pasta and refined carbs to buckwheat, amaranth, quinoa and sprouts all containing essential enzymes and probiotics.
“Food takes a lot of energy to digest. If your digestion is as efficient as possible and you are taking in nutrition without expending energy, then you can spend that energy working on recovery and regeneration.”
His recipes were the basis of his first book The Thrive Diet: the whole foods way to losing weight, reducing stress, and staying healthy for life, published in 2007. Containing over 100 recipes of plant-based food options, the book also features exercise-specific recipes for pre-workout snacks, energy gels, sports drinks and recovery foods. “I would get asked about being a vegan and so this book stemmed from that.”
Many books followed including Thrive Fitness: The Program for Peak Mental & Physical Strength and Thrive Foods: 200 Plant-Based Recipes for Peak Health. He also was editor-in-chief for Alive magazine and his own publication: Thrive.
Brazier moved to Venice, CA in 2008 and has immersed himself in the community and culture, investing in numerous enterprises. “I like to invest in companies that are making a difference,” he says.
One such company is Pulp Culture, a collaboration with fellow Canadian Mark McTavish. Inspired by fermented apple juice found in the Basque region of Spain, Brazier and McTavish have developed a light alcohol beverage from fresh juice that naturally ferments over three months. Going through a “wild fermentation,” the drink has no sugar or additives but has probiotics and B vitamins, and is just 100 calories.
Brazier has kept his Canadian connections and still works with Chang as an investor and advisor for Lyra, a brand marketing company in Vancouver. He also supports innovative plant-based products such as LOCA, a cheese source made from potatoes; Super Mush, a mushroom mouth spray; RISE, a Kombucha made in Montreal, and Thrive Market, an on-line market for organic goods.
He has also dabbled in film production on the ground-breaking movie The Game Changers, which put the spotlight on several elite vegan athletes and their reasons to adopt a plant-based diet. He was an executive producer with a number of celebrities including James Cameron, Lewis Hamilton and Novak Djokovic.
Brazier’s passion though is in food and the environment and ensuring nutrient dense ingredients are available to everyone. Enter Fiction, his new company under development—it will be launched next year—which brands itself as a ‘solutions company expressed through food.’
Summing up Fiction’s philosophy, Brazier says, “It’s about the nutrient to resource ratio, looking at land, water, and the amount of fossil fuels that we use in relation to the vitamins and minerals, antioxidants and protein that’s produced. It’s about spending the least amount of natural resource and getting the most nutrition back. It’s finding the efficiencies in the food system which help solve environmental and health issues, making sure people get enough nutrition as there are so many foods out there that don’t provide that.”
When launched, his Fiction products will include ingredients such as beta gluten from euglena (protozoa) to boost the immune system, DHA omega from algae to maintain brain health, plant sterols to reduce LDL (bad) cholesterol, and MCT oil, from euglena, to improve fat metabolism. These combined, he says will boost the ability to perform, mentally and physically.
Brazier has been a vegan for over 30 years and has his favourite foods. Sprouted bread, avocado sandwiches, arugula, greens, lentil pasta, tofu and tempeh are included in his plan. Does he see himself as a pioneer? “There were others like me, Dave Scott, the triathlete, was vegetarian so I wasn’t the only one,” he says modestly.
Although not competing any more he runs regularly and mountain bikes. He isn’t interested in races, preferring to skip the crowds and spend hours on his own. “I love the pureness of running.” Every November he goes to New York, not to run the official
marathon course, but run 42.2 kilometres just to challenge himself.
He works out regularly at his local Gold’s Gym, which he calls a ‘classic gym.’ (Venice Beach was the first location for Gold’s in 1965 and made famous by celebrities like Arnold Schwarzenegger). “If I don’t lift weights I get too light, so I have to ensure I build muscle.” But he doesn’t have to worry about his weight and eats when he is hungry. He does have one craving though. “There’s nothing like a bag of potato chips after a long, hot run.”
Does he have any advice to anyone considering taking up a plant-based diet? “Start gradually and introduce new things into your diet. You don’t have to cut out meat and dairy right away. For me it started with those blender drinks, and I didn’t feel like eating as they were satisfying. Your palate will change—that’s what I noticed— and if you go back to have any dairy or meat you will find they don’t appeal because your taste senses have changed.”
Brazier feels that meat consumption in North America will decline over the years as people experiment with plant-based options. “Fake meat has its place if done well as people are transitioning.” He gives an example of a company out of Colorado making ‘steak’ from mushroom roots. “It’s companies like this that are creating great culinary experiences. They aren’t trying to be meat, they are trying a different way of making a nutritious, protein product.”
Brazier may not think of himself as a pioneer, but he was a trail blazer in his time. While in his early years he focussed on how he could become stronger and more efficient, he is now putting his energy and passion into helping others to become socially responsible about food efficiency and production.
