The Physiology of Yoga

Pranayama: Uncork the Power of the Breath

IMG_1216“Just take a deep breath.” This is likely an instruction you have heard whether you practice yoga regularly or have never set foot inside a studio. Almost intuitively, we know that stopping and taking a long, deep breath can help calm our body when we are feeling overwhelmed, anxious, or frustrated. Indeed, a host of research articles support the physiological benefits of  slow, deep breath. The breath can be maneuvered in many other ways to produce different physiological effects. The practice of controlling the breath, whether it be the rate, depth, or entry/exit point, is an ancient practice known as pranayama and stands alone as the fourth limb of yoga in The Yoga Sutras of Patanjali. There are countless modes of breath manipulation—each of which initiates a physiological event—that can lead to calming, energizing, heating, cooling, and cleansing effects, among others. By employing different styles of pranayama, we have the ability to influence several physiological systems, including cardiovascular, nervous, respiratory, digestive, and musculoskeletal.

The most basic form of pranayama is an equal, counted breath known as respiratory musclessama vritti pranayama. This yogic practice is equivalent to the slow, deep breathing techniques described in medical and scientific research on breathing techniques. To practice this breath, come to a comfortable seat and begin inhaling for a specified count, then exhale for an equal amount of time. The inhales and exhales can gradually be lengthened, stopping at the point when breathing becomes strained or is no longer comfortable for the practitioner. The most obvious benefit of this type of breathing is strengthening the accessory breathing muscles, such as the internal and external intercostals (located between the ribs). Since we are actively concentrating on inhaling for longer than normal, we utilize more of our lung capacity. The average person only utilizes about one-third of their total lung capacity in normal, uncontrolled breathing. When we actively manipulate our inhales and exhales, we strengthen the muscles and prepare ourselves for situations when the breath needs to be increased (like exercise).

Several other benefits of this type of breathing have been widely documented and include decreased blood pressure, improved tone in the autonomic nervous system, decreased anxiety, and improved digestion. But how exactly does a lengthened breath translate to changes across such a broad scale? The basic answer is that by guiding the breath in such a manner, we initiate a cascade of events that lead to up regulation of the parasympathetic nervous system (the “rest and digest” response) and a down regulation of the sympathetic nervous system (the “fight or flight” response).

baroreceptorsThe cascade begins with stretch receptors in the lungs, aortic arch (the blood vessel directly exiting the heart), and carotid arteries (blood vessels along the throat). Inside the lungs, an increase in the tidal volume (the amount of air inhaled) will activate the Hering-Breuer reflex. This reflex translates the increased activity of the stretch receptors to increased activity of the vagus nerve. The vagus nerve can be thought of as the main highway of the parasympathetic nervous system, as its branches exert influence over the heart, blood vessels, and many other organs. The net result is an increase in the release of “relaxing” hormones and a decrease in the release of “excitatory” hormones. A similar reflex also happens with baro-receptors in the aorta and carotid bodies in the carotid arteries; an increased stretch and volume of oxygen in the blood triggers a reflex that results in increased vagal nerve tone and, therefore, increased release of “relaxation” hormones. When the body is flooded with these relaxation hormones (such as GABA), the heart rate slows, blood vessels relax (resulting in decreased blood pressure), anxiety decreases, and digestion improves.

Another basic form of pranayama—and probably the most familiar to yogis—glottisis ujjayi breathing. Ujjayi breath is similar to the slow, deep breathing techniques mentioned above, but it adds a slight constriction at the back of the throat on the exhale, and requires the mouth to remain closed, forcing the nose to be the exit point for the breath. These extra elements provide the added component of heating the body, since heat does not escape the body as readily from the nose as it does from the mouth. This can be very useful in yoga practice, as we aim to build heat inside the body, but it can also be employed in everyday life when the body is in need of a temperature boost (cold, Boston winters, anyone?). While some might argue that the constriction at the back of the throat (initiated by the contraction of the glottis muscles) might provide an additional increase in pressure in the neck, there is not yet any scientific evidence to support this claim. Therefore, ujjayi breath does not necessarily increase vagal responses and parasympathetic reflexes above the response initiated from sama vritti pranayama.

Our breath has the potential to play a far greater role in our well being than simply delivering oxygen to the body. With even with the most simple manipulation, we can strengthen our musculature and positively affect organs and tissues throughout our entire body, thus altering our psychological and physiological states for the better. By incorporating elements found in ujjayi breathing to our daily lives, we can heat the body, helping to prepare it for exercise or to combat the elements. Bear in mind that these are just two of the most simple and common pranayama practices; there are many others that can be utilized to produce profound systemic effects. In upcoming posts, the physiological impact of more advanced pranayama practices will be explored, allowing us to dive deeper and fully uncork the power of the breath.

For more information about the author, Jessica Pate, or to access her other articles, visit her website HERE or check out The Physiology of Yoga on Facebook. 

Feach-a Teach-a: Kate Greer

Where are you from and how long have you been in Boston?katechicken
I was born in Boston and have been relocated here since I was pregnant with my first son, seven years ago now.

What was your first yoga class like?
My first yoga class was a hot yoga class – at the original Baptiste studio in Cambridge! My friend who had also quit her varsity sport in college (mine was downhill skiing) dragged me into it, saying "I just think you're going to really like this, Kate"… Boy, was she right!

What’s your favorite pose to teach?
I don't really have a favorite pose, per se, but the pose I teach most frequently and think is, overall, the most beneficial to the most people, is squatting – any form. If you want to live comfortably, squat.

As a practitioner, what pose makes you cringe?
If anything makes me cringe, I try to examine that relationship… So I have to admit, the poses I want to run away from are usually the ones that I start to turn toward. Those poses these days? Mayurasana, every day. And some of the poses that are a little bit more difficult after having children, like deep twists :-)

Where can we find you when you’re off your mat?
With my two sons, teaching meditation, baking, and when I feel like I have leisure time, hanging out with my chickens. 

What’s your favorite or the most random song on your class playlist right now?
I don't really use playlists anymore since I mostly trying to use instrumental music or kirtan my classes… But the music that I play most often with my children is either kirtan or reggae – every song when my son asks what it's about, the answer is the same: God.

The Physiology of Yoga

The Yoga Detox - What is Real and What is Garbage?

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.

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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 photorequire 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.

colonThe 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 photo-2(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.

For more information on the author, Jessica Pate, or to access her other articles, visit her site HERE

Yogi of the Month: Sam Whyte

Name? Sam WhyteIMG_1214_copy1

Fun Fact? I can speak with a pretty convincing Scottish accent.

Favorite pose? Vrkasana (Tree pose). I think it's because it seems to have roots and wings.

When not on the mat? Walking my dog at the reservoir, hanging with my teenage daughters, looking for singing opportunities, discussing saving the planet with my husband.

How long have you been practicing? This month is my first year anniversary of regular practice.

Latest yoga break through? A particularly strong, lovely feeling chaturanga dandasana. The teacher called it "pristine."

How has yoga impacted your life? Yoga provides a path to move through physical challenges, which of course I can't do without addressing their emotional components. Practice is teaching me to listen to my body and honor myself wherever I am in the present moment. Yoga has also brought me to this amazing community that is CCY and continues to be a place of wisdom, generosity, love, laughter, and great compassion.

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