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The Science of Yoga

We've all heard that practicing yoga is incredibly beneficial for our overall health. If you have ever been to one of my yoga classes, you probably remember feeling pretty amazing afterwards & left the class wondering what exactly was happening to you during that class that made you feel so chilled-out, happy, energised & positive.

After practicing for over 20 years, I have become more and more dependent on yoga but until recently, I was pretty clueless as to why I loved it so much. Like most people, I noticed the obvious mental and physical health benefits of a regular yoga practice. I could go from feeling hugely stressed - my whole body wound tight like a knot after an awful commute on the London Underground (if you’ve been there, you’ll know I’m not exaggerating) - to entering a yoga class, taking some deep breaths, going through the yoga poses with the breath and then feeling totally wonderful and zen.

All exercise (running, gym, swimming) makes you feel good but nothing like yoga. Yoga has definitely become my go to solution to sort out all of my troubles.

So what exactly is happening when we step on the yoga mat? Well, you'll be pleased to know that I have looked into this and I’m going to attempt to explain in plain English what goes on inside your body that makes you feel so good. Also how different poses affect you in different ways. Stick with it… it’s worth the read!

In a nutshell

So it turns out that practicing yoga affects and changes the brain, resets the chemical balance of the blood and fine-tunes the nervous system. All of this means reduced stress, heart rate, blood pressure, improved immunity & disease prevention. Some research has shown that yoga does all of this more so that any other form of exercise. By ‘yoga’ I mean yoga poses (asanas), breathing

(pranayama) & meditation.

Yoga ‘fine-tunes’ the nervous system

Science has shown that yoga brings about deep relaxation of the nervous system that regulates the internal muscles, organs and instincts (the autonomic nervous system). Within this nervous system you have:

- the sympathetic nervous system – the body’s ‘accelerator’ - promotes the body’s fight or flight response (inhibiting digestion and moving blood to the muscles for quick action). It tells the adrenal glands to emit the stimulants adrenaline and cortisol (a major age-accelerating hormone), speeding up bodily functions;

- and the parasympathetic nervous system – the body’s ‘brake’ - The rest and digest nervous system, responsible for calming the nerves, promoting the absorption of food and limiting the flow of adrenaline. It directs blood to the digestive organs, lymphatic circulation and endocrine glands and reduces inflammation (the cause of many diseases).

The accelerator and the brake

So the ‘accelerator’ and the ‘brake’ work in synergy to control the body’s overall energy flow, one preparing for action and the other for energy conservation.

By moving from poses which stimulate the accelerator (any pose that works the muscles, exciting the sympathetic nerves) to poses which apply the parasympathetic break, for example forward fold, we are essentially honing the ability of the brake to calm us down.

Let’s look at Shoulder Stand

Shoulderstand or (Sarvangasana in Saskrit) presses the parasympathetic brake, making it one of the most relaxing postures in yoga. It does this by taking control of the regulation of blood pressure.

Within the carotids (major arteries which run through the front of the neck carrying blood to the brain) sit carotid sensors, ensuring that the brain gets the right mount of blood and measuring blood pressure. When the body is in shoulder stand, the chin presses deeply into the neck and upper chest, making the local blood pressure very high. This sends the parasympathetic nervous system into action applying the brake as it believes that the brain is receiving too much blood and could be damaged. It tells the heart and the circulatory system to reduce the flow of blood. Blood pressure and heart rate are immediately reduced.

How about Downward Facing Dog and Forward Fold?

These are just two of the many inversion poses (where the head is below the heart) that we practice in yoga. There is a sensor in right atrium of the heart which receives blood from the veins. This sensor monitors the atrium’s fullness. When blood pressure is deemed too high, it signals the heart to slow down. When the body is in an inversion, the body it is tricked into slowing the heart down as it believes that too much blood is flooding the heart’s atrium.

Heart rate and blood pressure are reduced and blood is redirected towards restorative functions like digestion, the immune system and reducing inflammation. An effective yoga practice, therefore, involves poses that press the accelerator then the break over and over, so that the autonomic systems gets a good workout. So for example, moving from backbends to inversions repeatedly.

Yoga tones the vagus nerve

In 2002 an immunologist in New York reported that the vagus nerve has a big role to play in controlling inflammation in the body, which is responsible for many chronic conditions like sepsis, lupus, pancreatitis and rheumatoid arthritis.

The vagus nerve is the most important nerve in the body – traveling from the brainstem to the torso where is spreads throughout the body to the lungs, heart, stomach, liver, spleen, colon and other parts of the abdomen.

The vagus nerve’s key action is central to slowing down the heartbeat and the regulation of the immune system. Studies have shown that yoga tones the vagus nerve, which has huge implications for disease prevention and overall health.

The ‘muscle of the soul’ – THE PSOAS

Many yoga poses work on stretching and releasing the psoas muscle. This is deliberate as the psoas holds a lot of our pent up tension and mental stress and can have a deep emotional hold over us. Perhaps this is why the psoas is so often referred to as the ‘muscle of the soul.

The psoas is the largest muscle in the body and the only muscle to connect the spine to the legs. It is linked to our “fight or flight” mechanism, as it is controlled by the most ancient part of our brain stem and spinal cord, called the reptilian brain, known for its survival instinct.

Tensions can be held in the psoas and the surrounding fascia that effect our emotional balance and calmness. A tight psoas muscle can mean physical and mental stress, anxiety, depression, digestive and breathing issues. Fear can manifest in an exaggerated way in people who have constricted psoas. Releasing the psoas therefore, relieves mental stress and promotes overall well being.

The abdominal brain

Additionally, the psoas is connected to our ‘abdominal brain’ or emotional center of the body. The abdominal brain is made up of a huge network of nerves and functions independently from the ‘top’ brain. When you feel guilt or fear in your abdominal brain, the emotional information travels from the psoas, up the spinal column to the brain. If the psoas is healthy and free it passes on accurate information. If it is tense, unhealthy and tight, the information will be inaccurate and the person will likely feel emotional discomfort.

So by targeting the psoas during our yoga practice and relieving any tension there, we are working to relieve a major blocker to our emotional and mental health.

Yoga and feel good chemicals

Studies have also shown that levels of a major neurotransmitter – GABA, increases significantly after a single yoga class, more so than after any other type of exercise. GABA regulates the nervous system and depression and anxiety are linked to low GABA levels. High levels of GABA have a calming effect and when drugs like Valium and alcohol bind to GABA receptor sites, they promote its actions as a sedative and relaxant. GABA released over a period of regular yoga practice can help the brain rewire itself to react in a calmer, less anxious manner when faced with everyday situations. Serotonin, dopamine and melatonin levels are also found to increase after a single yoga class.

Endorphins and DHEA

Endorphin levels are also greatly increased through practicing yoga. Endorphins are neurotransmitters that the body uses as a pain killer which make us feel generally happy. In the same way that a runner experiences a ‘runner’s high’ after a long run, yoga practitioners experience this endorphin rush. Practicing yoga also boosts our levels of DHEA which is what researches call the ‘longevity molecule’ as it is a stress and cortisol reducer and one of the most important hormones in the body.

Yoga can slow the biological clock!

In 2008 a team at University of California found that yoga increases the production of telomerase, an enzyme linked to cellular longevity. This discovery, showing that yoga can slow the bodies biological clock, counteracting the forces of aging, won the Nobel Prize.

Telomeres act as an internal clock that determine the lifespan of cells. Yoga has been shown to preserve telomeres which are eroded by chronic psychological stress and other lifestyle factors leading to aging. Levels of Telomeres have been shown to shoot up in studies involving the regular practice of yoga. These findings have implications for cellular longevity, disease prevention, tissue renewal and indeed increases in life span!

Yoga, Depression and Stress

Yoga manages the stress response and helps a person cope with anxiety, stress, emotions and depression. This has huge implications as globally, depression affects more that one hundred million people and results in over a million annual suicides (more deaths than are brought about by war and crime together). As we already looked at, yoga releases natural substances in the brain that act as strong antidepressants.

The link between stress and illness

A new biology called Epigenetics has shown that contrary to what we had previously thought, only 10% of illness is related to our genes and 90% is related to stress, which is essentially the mind over-working. The practice of yoga can counteract this by bringing the mind into a focus.

By practicing controlled breathing or pranayama during yoga (taking fewer breaths; filling the lungs up to full capacity to increase lung volume; holding the breath in; breathing less frequently), and practicing yoga asanas (poses), we can reduce our blood pressure and our stress levels.

Yoga changes your brain structure

Neuro Imaging has shown that stress actually shrinks the brain & contemplative practices like meditation, (when a person is focusing their attention with controlled breathing) can, over time change the brain structure.

These changes then affect the individual’s stress response.

So there you have it!

Yoga is everywhere. It is estimated that globally more that 250 million people practice yoga. With such a burgeoning following is it any wonder that there is an increasing need for an understanding of the science behind what is going on when a person steps on the mat and carries out this ancient practice?

These are just a few of the scientific findings that have cemented what we had already started to notice about the effects of yoga on a behavioral level. The hope is that this new western science can give people the language that they need in order to enter into yoga and reap its many incredible benefits.

So if you needed any more convincing that yoga is an incredibly worthwhile practice that can help to keep you healthy, happy and even young, there it is!

I'll leave you on that note and hope to see you on the yoga mat soon!

- Namaste –


Respira Yoga London

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