Most of us who have practiced
yoga for any length of time have eventually encountered a statement from a
teacher, magazine article, book or website telling us that shoulderstand has a
beneficial effect on our system through its action on the thyroid gland.
Although this statement seems to be most prevalent among Iyengar-style
influenced teachers, it is not exclusive to this style. Similar statements have
been made by Sivananda style teachers, and I clearly remember hearing it from
my Kripalu teacher nearly 13 years ago. I was then, as now, curious about the
validity of that statement. Though I don’t feel I need to understand the
scientific basis behind every benefit offered by yoga, the specificity of the
association of the pose shoulderstand and thyroid function struck me as worth
thinking about. Shoulderstand, “the queen of asanas” is given prominence by
Iyengar teachers and practitioners as a pose of particular benefit to women,
especially in alleviating discomfort and ailments associated with hormonal
changes during maturation and menopause. Clearly, information gained from decades of experience has provided
B.K.S. Iyengar and his daughter Geeta abundant anecdotal evidence that
shoulderstand has numerous benefits, as described in Yoga, the Path for
Holistic Health, and Yoga, a Gem for Women. Iyengar’s students continue to
recommend of this pose as therapeutic for women as can be seen, for instance,
in Patricia Walden and Linda Sparrowe’s The Women’s Book of Health and
Wellness. Popular literature describing health benefits of yoga is abundant, as even a relatively casual collector of yoga books will know.
Curious as to the scientific basis for the connection between shoulderstand and thyroid function, I started searching the literature for peer reviewed, scientific studies that might provide experimental evidence for this claim, using the standard search engines and databases available to the university I attend. It didn’t take long to realize that scientific studies on the physiology of shoulderstand’s effects on the thyroid gland, were extremely scant. Apart from a small handful of studies published in the mid-70’s in the Indian Journal of Medical Research, experimental evidence for shoulderstand’s effect on thyroid function is notably lacking. No studies were located that seem to have built on those early findings.
Does any of this matter? For the average practitioner who enjoys including shoulderstand in their regular practice and enjoys the physical, mental and emotional benefits from the pose, there is certainly no reason to worry about the science behind it. However, as yoga students begin to perceive yoga as a form of therapy or complementary and alternative medicine (CAM), and health care providers and HMOs respond to the public’s drive to include CAM as part of their coverage, the questions arise: can yoga be prescribed as a health care practice, akin to physiotherapy? And if so, can the student/client/patient ask that it be included as part of their coverage? Objective evidence of the efficacy of yoga would certainly assist that process – if that process is what we really want as students, clients or patients. Experimental evidence has been steadily accumulating for benefits on musculoskeletal disorders and factors in cardiovascular disease risk, among others, but remains scarce for yoga and endocrine function. There have, however, been pilot studies demonstrating that restorative practice (including shoulderstand) has alleviated hot flashes in menopausal women. These provide encouragement for further studies on a larger scale using appropriate randomization and control groups.
Part of me is hesitant at the thought of offering yoga up to the altar of the controlled double blind, but in a practical sense, perhaps allowing yoga to be integrated into the health care system as a complementary therapy could still be consistent with one of yoga’s main purposes – to alleviate suffering. The removal of sources of discomfort, disease, and physical ailment remains consistent with Patanjali’s aphorism 1.30: “The inner obstacles that disperse the mind are sickness, mental inertia, doubt, haste, apathy, intemperance, errors in judgement of oneself, lack of perseverance, and the inability to stay at a level once reached.” Many of us who practice yoga have already experienced a taste of relief from these obstacles. Will validating yoga through science contribute to helping others get a taste of that relief? Of would the process of scrutinizing yoga through western scientific methods take something away from a holistic practice meant to address all aspects of human nature?