by Ellen Tousaw
You don’t have to go far into wellness culture to hear some pretty impressive-sounding claims about Yoga:
“Prevent heart disease!”
“Boost your immune system!”
“Improve your metabolism!”
But how often do we stop and think critically about these sweeping statements? Are they true? In short, yes. Yoga makes you healthier. It’s been proven by objective, scientific research.
(1) It helps prevent cardiovascular disease
The cardiovascular system is controlled by many factors, but perhaps the most important is the autonomic nervous system. The autonomic nervous system controls things such as blood pressure and heart rate – imbalances in which can cause hypertension, stroke, heart attack, and overall poor cardiovascular health. This means that yoga has the potential to help prevent chronic cardiovascular disease.
The autonomic nervous system is divided into two main branches: sympathetic and parasympathetic. The sympathetic nervous system prepares the body for stressful situations by increasing heart rate, blood pressure, sweating, and energy shuttling to muscles. The parasympathetic nervous system is responsible for the relaxed state; it slows the heart down, stores energy and rebuilds tissues, and promotes digestion. We know that an imbalance towards the sympathetic system results in stress and tension. We also know that chronic stress and tension contribute to cardiovascular disease. It’s easy to appreciate, then, that lowering stress through yoga, breath work, and meditation can enhance our heart health.
While we often think of the autonomic nervous system as the “automatic nervous system”, meaning it involves bodily functions that are beyond conscious control, we do have an incredible capacity to regulate it with our breath. In fact, pranayama has been shown to reduce sympathetic activity in as little as seven days of practice! Slow and deep breathing (about 5 breaths per minute), rather than faster and rhythmic breathing (like kapalabhati) is particularly effective in decreasing sympathetic and increasing parasympathetic activity. The open-spirited and inquisitive yogi in you is likely asking, “but HOW?!” Unfortunately, the mechanism of these effects is not completely understood, and there are many complex physiologic factors involved. It is proposed, however, that deep breathing stretches lung tissue, which sends inhibitory nervous signals that synchronize the lungs, heart, limbic system (emotional centre in the brain), and cerebral cortex (part of the brain involved in cognition, logic, perception, and sensation).
Another example of how yoga benefits cardiovascular health is through a hormone called adrenomedullin. This little-known hormone is a mighty vasodilator – meaning that it relaxes blood vessels, thus lowering blood pressure. A recent randomized controlled trial found a significant drop in blood adrenomedullin levels in participants after having completed five weeks of twice-weekly yin yoga.
As a side note, adrenomedullin also contributes to cell growth, and high levels of adrenomedullin are predictive of future development of some tumours. So not only does lowering your adrenomedullin through yoga protect you from heart disease, but it decreases your risk of cancer, too. Are you convinced that yoga is good for you yet?!
(2) It supports immune function
The immune system is a network of glands, nodes, and organs that function to protect the body from harmful infectious organisms like bacteria, viruses, and fungi. Leukocytes (white blood cells) are the main actors of the immune system; they circulate through the body, recognize infection, and signal countless other factors to mount a response to fight it. The benefits of yoga on immunity all boil down to one thing that we’ve talked about before: stress. We’ve all experienced this: you get a sore throat a couple days before an important presentation; cold sores seem to crop up only during exam season; your skin breaks out the night before an interview.
The immune system is complex. Thousands of molecules, hormones, and neural signals interact to provide immunity. Stress influences immunity in two main ways. First, the sympathetic nervous system is in overdrive. Sympathetic fibres link the brain to immune organs (bone marrow, thymus gland, lymph nodes, spleen) and influence their activity. Secondly, the endocrine system, which is very sensitive to stress, secretes hormones that influence white blood cells’ distribution and function.
Objective research shows the effects of yoga on immunity. In one study, eight weeks of hatha yoga reduced blood levels of cytokines (molecules in the body that promote inflammation), thereby diminishing full-body immune response. In another, natural killer cells (immune cells that serve as early defense against infection) were more numerous and more active after mindfulness exercises. Studies have even reported links between massage therapy and number of infection-fighting white blood cells.
So, what do we take away from all this? Yoga is not a cure-all. You cannot down-dog your way out of strep throat, or meditate your sinusitis away. You can, however, give your body its best shot at avoiding infections in the first place through regular stress-relieving practices, yoga and meditation included.
(3) It regulates metabolism
Yoga is known to influence various hormones related to appetite and nutrient metabolism. Ghrelin, for example, is a hormone that stimulates hunger. Perhaps counterintuitively, though, it is generally lower in people with obesity and higher in people with average or low body weight. Ghrelin plays in important role in metabolism by contributing to long-term regulation of body weight, glucose, and cholesterol. One study showed that, after having practiced yoga for one year, participants’ ghrelin levels were higher than at baseline, indicating ameliorated control of metabolism.
Ghrelin isn’t the only metabolic hormone affected by yoga. Glucose (blood sugar) metabolism, for example, is maintained in delicate balance in healthy individuals. An imbalance in glucose metabolism can lead to diabetes and obesity. In ways that are not yet fully understood, yoga has the potential to improve blood glucose levels. For example, relaxation breathing exercises can stabilize blood sugars immediately after a meal, while regular yoga practice can normalize unhealthy glucose in the longer term.
Cardiovascular health, immunity, and metabolism are extremely complex processes that are determined by genetics, environment, diet, physical activity, and innumerable other factors. While practicing yoga is not a guarantee of pristine health, it certainly contributes in concrete ways to the prevention of chronic disease. Don’t hold your breath (in fact, breathe deeply!), but a time when doctors prescribe yoga may not be too far away.
Read about the Benefits of Meditation here
Boost your own health benefits at one of our Bali yoga teacher trainings!
Chen N, Xia X, Qin L, et al. Effects of 8-Week Hatha Yoga Training on Metabolic and Inflammatory Markers in Healthy, Female Chinese Subjects: A Randomized Clinical Trial. Biomedical Research International. 2016 July; 1-12. DOI http://dx.doi.org/10.1155/2016/5387258
Daukantaite D, Tellhed U, Maddux R, et al. Five-week yin yoga-based interventions decreased plasma adrenomedullin and increased psychological health in stressed adults: A randomized controlled trial. PLoS ONE. 2018 July; 13(7). DOI https://doi.org/ 10.1371/journal.pone.0200518
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