The Physiology of Yoga

Book Preface

Andrew and Matt artfully revere yoga and its tradition while shining a critical spotlight on the claims teachers often make. They have identified a need within the framework of anatomy education for yoga teachers and produced this book as an exemplary way to
inject critical thinking into these programs. The Physiology of Yoga balances research, empiricism, anecdote, humor, and passion, making it a welcome addition to any yoga teacher’s library.
Yoga schools providing education at any teaching level can use this book as part of their curricula. The anatomy and physiology terms are presented in a manner appealing to yoga teachers—not too academic or medicalized yet not too rudimentary. The book attracts an enthusiastic reader who cares about a sustainable yoga practice and wants to do right by their students when stating the benefits (or risks) of the practice.
In my years as an anatomy and biomechanics educator for yoga teachers, I have found our community to be quite insular. We tend to learn from each other, share within our own spheres, and trust what our teachers say. While this makes for an impassioned community, it also supports the flow of misinformation. Fortunately, social media is beginning to change that, as is the publication of many books on the subject written by authors like myself and the authors here, who have stepped outside of the container and continued their education in other fields of study. The academic rigor of graduate level work of such writers provides the perfect catalyst to shift the narratives and allow for more uncertainty among yoga teachers. Paradoxically, being less certain creates more expertise and trust among the leaders in yoga education. As it does in science.
The Physiology of Yoga addresses the major systems of the body and the common ailments within them yoga promises to fix. The text is extremely modern, as it captures a wide range of popular opinions within the mainstream cultures of fitness and wellness. The authors seamlessly refer to research when debunking while simultaneously hinting, “Hey, if it works, it works, and if you feel better, you feel better,” a sentiment often disregarded by the Western medical authority. Andrew and Matt kindly remind you that a singular anecdote or case study is not enough evidence to make powerful claims, while also appealing to your values with their own personal stories and opportunities to “try it yourself.” Among all this opportunity to witness, and perhaps challenge, the reader’s bias, special attention is still paid to the yoga teacher’s scope of practice, which is often forgotten when therapeutic effects of yoga enter the conversation.
The final chapter includes a variety of practices for different levels of exertion, presented with surprisingly classic cueing. What I appreciate about this is the authors demonstrate it’s okay to suggest when to inhale or how to align your feet. Often, recognizing that alignment rules aren’t universal creates confusion and frustration because teachers now don’t know what to say. The instructions within provide a non-judgmental and curious way to approach the poses without destroying the script. The Physiology of Yoga has my seal of approval.

Yoga Educator
Research and Adjunct Faculty at Arizona State University Author of Yoga Biomechanics: Stretching Redefined www.JulesMitchell.com

We (the two authors of this book) have been studying anatomy and physiology in some shape or form for more than 20 years, and we still regularly find ourselves in awe of how incredible the human body is. This book is the perfect opportunity for us to share this passion and relate the science to yoga.
In recent years, we have discovered a joy in examining the many “old wives’ tales” that tend to spread like wildfire through the yoga community. Does Headstand (Sirsasana) stimulate the pineal gland? Can yoga help to manage anxiety? Do twists detoxify the liver? While not everything has to be evidence-based or quantified, we believe in the importance of trying to separate theory from fact. But our ultimate aim is to inspire people to appreciate their body and love their yoga practice. Yoga and movement, after all, offer countless benefits. Our hope, in writing this book, is to inspire yoga and movement teachers to have more confidence and less fear in working with people’s bodies and for practitioners to have the knowledge to help themselves in their yoga practice. Through yoga, we benefit from so much more than just a good stretch; we come to know ourselves better. We hope you learn something from this book that helps you understand yourself a little better.
Before exploring how yoga affects the physiology of each system, we must first define what we mean by yoga and physiology—and explore how everyone might benefit from critical thinking.
WHAT IS YOGA?
Yoga is a philosophical practice or discipline originating from South Asia. The
word yoga is derived from the Sanskrit root yuj, meaning to join, yoke, or unite. Per yogic scriptures, the practice of yoga reminds us that not only are our mind and body connected, but our individual consciousness is inherently linked with that of
the universal consciousness. The eight limbs of yoga described in Patanjali’s Yoga Sutra are ethical principles regarding our relationship to others and the world around us (yama), internal disciplines (niyama), the physical practices of posture (asana), breathing exercises (pranayama), withdrawal of the senses (pratyahara), concentration (dharana), meditation (dhyana), and unutterable joy (samadhi). The eight limbs in themselves are not yoga but ancillary practices in support of yoga. So, while we will focus more on the physical aspects of yoga in this book, we recognize that yoga is so much more than this.
WHAT IS PHYSIOLOGY?
Physiology can essentially be thought of as the science of life. It is the branch of biology that aims to understand the mechanisms of living things, from the basis of cell function to the integrated behavior of the whole body and the influence of the external environment. The field of physiology is constantly evolving as research advances our understanding of the detailed mechanisms that control and regulate the behavior of living things. Research is also crucial in helping us to determine the cause of disease and develop new treatments and guidelines for maintaining our health.

CRITICAL THINKING
In a world of uncertainty, it can be tempting to wish for definitive answers: the one right way to practice yoga, the one right diet to follow, the one right way to live. However, particularly in a time when anyone can publish anything, it is easy to find contradictory answers to any question. This section explores the topic of critical thinking with tips on how to navigate all the conflicting views and opinions that are shared about many topics in the yoga world.
We probably like to believe that we think logically, reasonably, and without bias, but that is not always so. According to philosopher-educators Richard Paul and Linda Elder, two important figures in the development of critical thinking, “Much of our thinking, left to itself, is biased, distorted, partial, uninformed or down-right prejudiced. Yet the quality of our life and that of what we produce, make, or build depends precisely on the quality of our thought” (Paul and Elder 2019, p. 2). Thinking logically, reasonably, and without bias must be systematically cultivated, they argue.
Paul and Elder (2019) define critical thinking as “the art of analyzing and evaluating thinking with a view to improving it” (p. 2). Critical thinking is based on intellectual values that most of us would probably like to cultivate: clarity, accuracy, precision, consistency, relevance, sound evidence, good reasons, depth, breadth, and fairness.
Critical thinking requires asking ourselves questions such as: What are my beliefs on a topic? What information am I using to come to my conclusion? What assumptions have led me to this conclusion? From what point of view am I looking at this issue? Does the evidence support my conclusion? What evidence against my hypothesis exists?
That last question is a particularly important one. We are all at times guilty of confirmation bias, a cognitive prejudice where we only seek out or listen to evidence that supports our beliefs. However, critical thinking asks us to seek out evidence against our beliefs, against our hypotheses.
Critical thinking can help us sift through all the sometimes contradictory information you might find on any given topic. One month, a study might come out showing that wine, in moderation, is good for you. The next month, a study might show that any alcohol consumption is harmful. Within the yoga community, you might hear one teacher say that sitting bones must remain on the floor during a seated forward fold, while another might encourage everyone to pull their sitting bones back. See figure 1 for a guide to using critical thinking when reading an article about a scientific finding.
EVIDENCE AND RESEARCH
Evidence is the available body of facts or information indicating whether a belief or proposition is true or valid. While most people in an asana class are probably not thinking about evidence while flowing through Sun Salutations, many yoga teachers make claims that lack any real evidence regarding the physiological workings of yoga. These claims are also often shared on yoga teacher trainings, on wellness blogs, and in books on yoga. Consider the claim that Shoulder Stand (Sarvangasana) stimulates the thyroid gland or that twists cleanse the liver. Both of these claims are based on speculation, lack evidence, and do not have sound physiological reasoning behind them.