My blog from two weeks ago, titled "Lesser Known Yoga Benefits", initiated a couple reader comments that warrant a thorough and well-researched response.

The passages in question basically stated that, as the popularity of yoga increases in the Western world, more and more research and scientific studies are being and have been conducted on yoga, correlatively to whole body benefits. By reading through's conclusions from professional studies conducted and published by Stephen Cope of the Kripalu Center for Yoga and Health, I reported that through series' of asanas and breathing practices, cortisol production is increased in the body (the "stress" chemical and horomone secreted by the sympathetic nervous system).

This is in fact true, to an extent. When we practice flash-breathing during warm-ups (aka - shallow breathing, hypopnea, disturbed breathing, thoratic breathing, or upper chest breathing, we are basically self-imposing hyperventilation, comparative to the breathing patterns experienced during a panic attack. This activates the the flight or fight mechanism included in the autonomic nervous system: resulting in higher levels of cortisol secretion by the adrenal gland, which is part of the sympathetic nervous system. Cortisol is also secreted when vigorous forms of yoga are practiced like vinyasa flow, power yoga, sun salutations, Bikram, and any other form of exercise (e.g. running) that rapidly increases the heart rate.

The sympathetic nervous system is one of two parts of the autonomic nervous system. The other part is the parasympathetic nervous system. The parasympathetic nervous system is activated during meditation, the cool down period and floor work at the end of class, savasana, and mellow styles of yoga like mellow asana practices like gentle hatha yoga, yin yoga, restorative yoga, and even some slow vinyasa when it's coordinated with pranayamic breathing. We often hear yogis and instructors use the term "blissed out" to describe our peaceful state of mind most student feel at the end of class. The scientific explanation is the drop in cortisol by the autonomic nervous system described here. Instead of "fight or flight" response, the body goes into the 'relaxation response'. Cortisol production is decreased, and anxiety melts away like the sweat from the skin.

So, yes, yoga ultimately leads us to decreased stress and anxiety, because cortisol levels decrease and are reversed during the cool-down process, shavasana, and meditation. Final levels of cortisol (if measured after class), depend on the entirety of active asanas, inactive asanas, and meditations combined. And here's an interesting twist: many studies have shown that if levels of cortisol drop slightly after meditation and inactive poses. However, if you practice more a more rigorous, active, cardiovascular-style class that includes savasana/meditation afterwards, the cortisol levels will initially increase but by the end of the class, drop well below the levels measured of those who only meditated. In other words, to get the fullest relaxation out of meditation, a brisk series of sun salutations are likely to make your meditation more effective.

By: Jessica Adams (G+)

Share your comments below...