Yoga And Endocrines

from enocrinesystematlas.gif / ama-assn.org

A VARIETY OF GLANDS produce and secrete hormones needed for normal functioning of the body: energy/lethargy, metabolism, sexual response, water regulation, sleep, mood, reproduction, and basic tissue functioning. 

“Hormones” are complex chemicals, such as melatonin, progesterone, lutropin, dopamine, estrogen, thyroxine, thyrotopin, corticotropin, epinephrine, and testosterone.  There are complex feedback loops between the various glands, and also with the nervous system and other organs that also secrete hormones.  The endocrine glands themselves are complex and have fascinating aspects such as retinal cells and neurons or gastric-like cells so that they “relate” [as an aspect of their evolutionary origins] with other body structures.

Yoga literature praises the benefits of yoga for optimizing the endocrine system, with no references to clinical research on the effect of yoga on the endocrine system.  When statements involving healthful outcomes of many body-mind practices are traced back, they often occur originally as statements by founders and previous practitioners and are essentially beliefs.  Interesting, endocrine glands occur throughout the body and are located almost at the center point of the seven popular chakra psycho-energetic centers (e.g., pineal/6^th chakra/middle of forehead).  For some yoga practitioners, the endocrines are described as the physical manifestation of a subtler, spiritual body.  But here, it might be acknowledged that the popular sense of seven chakra is abstruse rather than an explicit fact, with other models of yoga ranging from 5 to 20+ chakra and, for some practitioners, even a sense of sub-chakras within each major center.

The endocrine system might function somewhat autonomously, for example, with the pituitary gland regulating the amount of thyroxine (controlling cell metabolism) or another gland regulating salt and water balance, etc.  However, the endocrine system might be more accurately termed the neuroendocrine system, wherein central nervous system (CNS) affects the hypothalamus that, in turn, affects the pituitary gland (or “master gland”) to create a system of balances, with one gland capable of stimulating a response and another gland capable of inhibiting this response.  Either an external stimuli that produces fear or an internal disorder such as physiological depression in turn provokes CNS the endocrine system.  Along with the pituitary gland, the pineal, adrenal, thyroid, parathyroid, thymus and reproductive glands form the heart of the endocrine system.

Claims of effects of a spcific pose on a specific gland have not been established.  The key point is to begin to recognize that yoga is affecting the endocrine system, just as it also affecting the respiratory, vascular, lymphatic systems as well as systems less in our awareness such as the digestive system. 

Yoga impacts the neuroendocrine system, just simply as a form of external stimuli.  Intentional or mental stimulating the nervous system to relax by stilling and reducing the breath cycle, the flowing movement of yoga sequences, and the adjunct effect of pressure on the glands through poses such as inversions and neck bends clearly affects the neuroendocrine system.  In the quiet and calmness of restorative-yin yoga, a significant relaxation response is provoked.  This will involve the inhibition of endocrine secretions that stimulate the sympathetic nervous system.

Without any physiological measures of the endocrine system [such as blood levels of endocrine hormones during yoga practice or post-practice], it is logical to assume that either very active poses/active breathing [e.g. Kundalini “Breath Of Fire,” 2-3 breaths per second] or stillness “exercise” the endocrine system.  The healthful outcomes that yoga might provide for the neuroendocrine system [such as “normalized,” “regulated” or “balanced” or “optimized,” as well as the specific degree of change] make sense but remain subjective.

Inversions, such as downward dog and happy baby and shoulder stands/headstands, are strongly associated in yoga practice with stimulation of the endocrine system.  Poses that bend neck back to affect the thyroid and thymus [e.g., throat Lotus Kriya and Breath Of Fire] or that bend the spine back or forward [e.g., Camel or Forward Folds] to affect most endocrine glands.  And the variety of the sequence of poses of a yoga practice session “massage” all of the endocrine glands.

Overall,

• inversions and
• physiological relaxation and
• a sense of poses massaging the endocrine glands (as well as “pumping” the lymphatic system)

are three components that will likely affect the endocrine system in healthful, balancing way that has not been adequately measured [e.g., in terms of immediate or post-practice blood chemistry measures or studies with populations with specific endocrine disorders].

A cautionary sense of healthy” self-criticism in evaluating the benefits of any body-mind practice is recommended.  It is facile and perhaps misleading to assume that a specific pose will optimize specific endocrine functions.  Neuroendrocrinology is an extremely complex field of inquiry that involves all of the tissues of the body in elaborate feedback systems with complex secretions stimulating other secretions and fitting exquisitely to target receptor cells.