Main Science of Yoga: Understand the Anatomy and Physiology to Perfect Your Practice
Science of Yoga: Understand the Anatomy and Physiology to Perfect Your PracticeDK, Ann Swanson
Explore the biomechanics of 30 key yoga poses, in-depth and from every angle, and master each asana with confidence and control.
Did you know that yoga practice can help with age-related memory loss, or that the correct way to breathe throughout a sun salutation is influenced by what is happening to your organs as you move?
Recent scientific research now backs up what were once anecdotal claims about the benefits of yoga to every system in the body. Science of Yoga reveals the facts, with annotated artworks that show the mechanics, the angles, how your blood flow and respiration are affected, all the muscle and joint actions working below the surface of each pose, and much more.
With insight into variations on the poses and the specific benefits of different styles of yoga, such as kundalini and ashtanga, look no further than Science of Yoga to achieve technical excellence in your practice and optimise the benefits of yoga to your body and mind.
Did you know that yoga practice can help with age-related memory loss, or that the correct way to breathe throughout a sun salutation is influenced by what is happening to your organs as you move?
Recent scientific research now backs up what were once anecdotal claims about the benefits of yoga to every system in the body. Science of Yoga reveals the facts, with annotated artworks that show the mechanics, the angles, how your blood flow and respiration are affected, all the muscle and joint actions working below the surface of each pose, and much more.
With insight into variations on the poses and the specific benefits of different styles of yoga, such as kundalini and ashtanga, look no further than Science of Yoga to achieve technical excellence in your practice and optimise the benefits of yoga to your body and mind.
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SCIENCE YOGA of UNDERSTAND THE ANATOMY AND PHYSIOLOGY TO PERFECT YOUR PRACTICE US_001-003_SOY_Half_AND_TitlePage.indd 1 21/09/2018 11:05 US_001-003_SOY_Half_AND_TitlePage.indd 2 21/09/2018 11:05 SCIENCE YOGA of UNDERSTAND THE ANATOMY AND PHYSIOLOGY TO PERFECT YOUR PRACTICE Ann Swanson US_001-003_SOY_Half_AND_TitlePage.indd 3 21/09/2018 11:05 CONTENTS Preface 6 HUMAN ANATOMY 8 Cell to system 10 Skeletal system 12 Muscular system 18 Nervous system 22 Endocrine system 28 Respiratory system 30 Cardiovascular system 34 Lymphatic system 36 Digestive system 38 Urinary system 40 Reproductive system 41 THE ASANAS 42 SEATED ASANAS 44 Accomplished Siddhasana 46 Bound Angle Baddha Konasana 50 Cat Marjaryasana 54 Cow Bitilasana 56 Cow Face Gomukhasana 60 Side Bend Parivrtta Janu Sirsasana 64 Seated Twist Ardha Matsyendrasana 68 Child’s Pose Balasana 72 Camel Ustrasana 76 King Pigeon Eka Pada Rajakapotasana 80 STANDING ASANAS 84 Mountain Tadasana 86 Forward Fold Uttanasana 90 Senior Editor Ruth O’Rourke-Jones Senior Designer Clare Joyce Editor Alice Horne US Editor Karyn Gerhard Senior Art Editor Karen Constanti Design assistance Philippa Nash, Louise Brigenshaw Editorial Assistant Megan Lea Senior Jacket Creative Nicola Powling Jacket Co-ordinator Lucy Philpott Pre-production Producers Heather Blagden, Tony Phipps Production Controller Igrain Roberts Creative Technical Support Sonia Charbonnier Managing Editor Dawn Henderson Managing Art Editor Marianne Markham Art Director Maxine Pedliham Publishing Director Mary-Clare Jerram Illustrations Arran Lewis First American Edition, 2019 Published in the United States by DK Publishing 345 Hudson Street, New York, New York 10014 Copyright © 2019 Dorling Kindersley Limited DK, a Division of Penguin Random House LLC Text copyright © Ann Swanson 2019 19 20 21 22 23 10 9 8 7 6 5 4 3 2 1 001–310296–Jan/19 Health warning All participants in fitness activities must assume the responsibility for their own actions and safety. If you have any health problems or medical conditions, consult with your physician before undertaking any of the activities set out in this book. The information contained in this book cannot replace sound judgment and good decision making, which can help reduce risk of injury. All rights reserved. No part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted, in any form, or by any means (electronic, mechanical, photocopying, recording, or otherwise) without the prior written permission of the copyright owners. Published in Great Britain by Dorling Kindersley Limited A catalog record for this book is available from the Library of Congress. ISBN: 978-1-4654-7935-8 Printed and bound in China A WORLD OF IDEAS: SEE ALL THERE IS TO KNOW www.dk.com US_004-005_SOY_Contents.indd 4 04/12/2018 14:52 Chair Utkatasana 94 Crescent Lunge Anjaneyasana 98 Warrior II Virabhadrasana II 102 Warrior III Virabhadrasana III 106 Tree Vrksasana 110 Dancer Natarajasana 114 Triangle Trikonasana 118 INVERSION ASANAS 122 Downward-Facing Dog Adho Mukha Svanasana 124 Headstand Sirsasana 128 Half Shoulderstand Ardha Sarvangasana 132 Bridge Setu Bandhasana 136 Wheel Urdhva Dhanurasana 140 FLOOR ASANAS 144 Crow Bakasana 146 Plank Kumbhakasana 150 Side Plank Vasisthasana 154 Cobra Bhujangasana 158 Locust Salabhasana 162 Supine Leg Stretch Supta Padangusthasana 166 Supine Twist Supta Matsyendrasana 170 Q&AS 174 Joints and flexibility 176 Spinal care 178 Life stages 180 Meditation 184 Savasana 186 Stress 188 The brain and mental well-being 192 Chronic pain 194 Yoga therapy 196 Transformation 198 On the frontiers of science 200 Cautions 202 Glossary 206 Index 208 Bibliography 214 About the author and acknowledgments 216 US_004-005_SOY_Contents.indd 5 04/12/2018 14:52 As the daughter of a NASA scientist I was raised to have an analytical mind. A part of me craves method, data, and evidence. I started journaling at the age of seven, carrying my notebooks everywhere. I filled them with charts, graphs, observations, and plans concerning everything from what I ate that day to what to rent at the video store. I was a curious child, constantly asking, “Why?” My parents would send me to the trusty encyclopedia to look up the answer. At the same time, I have always been artistic, creative, and interested in spirituality. My notebooks are also filled with elaborate stories, poetry, and colorful drawings. My undergraduate studies in art led to burnout. Like many people, I came to yoga hoping to relieve stress and anxiety during a difficult time—with the added bonus of staying fit. I didn’t expect that yoga would transform me in an ineffable, seemingly magical way. When I started practicing, I aimed to make the picture- perfect poses. I slowly realized that yoga isn’t about performing the pose “perfectly,” but instead about being perfectly okay with my body and mind in the moment. Now I know that many of the most profound effects of poses transcend my anatomy of muscles and bones to shape my neurology, psychology, and energetic body. I vividly remember lying on my mat at the end of a yoga class with my eyes wide open, looking impatiently around when I was supposed to be relaxing. I thought “What a waste of time; I have work to do!” With practice, I started to enjoy the way relaxation and meditation practices made me feel. Now, through reading research, I know that when I meditate, I am literally reshaping my brain. Ultimately, I am impacting every single system of my body, and optimizing function. What more important work could I possibly do? My shifting mindset drew me to the Himalayas to study yoga, massage, and healing arts. My teacher, Yogi Sivadas, renewed my interest in science. I returned to the US and completed the pre-medicine courses, in pursuit of understanding how and why yoga works in such life-changing ways. I will never forget the first time I held a human brain in the cadaver lab. The experience was neither antiseptic nor clinical, but deeply spiritual. That three-pound folded gray mysterious mass once both computed mathematics and felt the depths of love. Holding that brain, I knew that the mind-body connection was a key mechanism behind yoga’s benefits. PREFACE US_006-007_SOY_Foreword.indd 6 02/11/2018 14:00 Science of Yoga is the book I wanted to read when I first started practicing yoga. In classes, teachers offer (sometimes conflicting) cues and claims—“Calm your nervous system by elongating your exhales;” “This pose will boost your immunity;” “Align your knee over your ankle”—and I constantly wondered, “Why?” For the past decade, through workshops, reading research papers, and completing my Master of Science in yoga therapy at Maryland University of Integrative Health, I have continued to fill my notebooks with facts, figures, sketches, and stories. Science of Yoga summarizes the notes I found most fascinating as a yoga student and teacher. This book is intended as neither a comprehensive text on human anatomy and yoga, nor a medical reference book; it is just the beginning. My intention is for this material to spark more curiosity and discussion about the science of yoga, and lead to more inspired yoga practitioners and professionals, more rigorous research, more public policies that encourage yoga in schools and healthcare, and, ultimately, more accessibility and acceptance. Through my research, scientific principles and evidence have demystified so much of the practice. Surprisingly, this made my transformative experiences feel even more magical. There is just so much more to discover. In the grand scheme of scientific inquiry, yoga research is in its infancy. However, now is an exciting and pivotal point in the field, with a remarkable increase in the quality and quantity of yoga research papers in the past few decades; the evidence supporting yoga’s benefits continues to grow rapidly. Science can explain the hows and whys of many things, but research studies, no matter how rigorously conducted, cannot compare to your personal, experiential evidence of healing and transformation. Only you can harness the power of yoga through practice. As with any scientific inquiry, I hope this book leaves you with more questions than answers, and brings out your inner child to playfully enquire, “Why?” Be well, Ann Swanson Mind-body science educator and certified yoga therapist www.AnnSwansonWellness.com PREFACE Scientific principles and evidence have demystified so much of the practice. US_006-007_SOY_Foreword.indd 7 02/11/2018 14:00 US_008-009_Opener_HumanAnatomy.indd 8 21/09/2018 11:09 HUMAN ANATOMY Most yoga anatomy books and courses focus on the musculoskeletal system, but research shows that practicing yoga affects all body systems. This section breaks down the key effects and benefits for each one. Study your anatomical systems as modern biology defines them—then, challenge yourself to shift to a yogic perspective, that of unity. Experience your extraordinary body as an interconnected whole. US_008-009_Opener_HumanAnatomy.indd 9 21/09/2018 11:09 10 HUMAN ANATOMY As in design, a key concept in biology is “form follows function”—this means that the physical structures of your body reflect their specific tasks. Anatomy is the study of these body structures and physiology is the study of their functions, or how your body works. BUILDING BLOCKS Atoms are the building blocks of matter; cells are the building blocks of biological life. Approximately 37 trillion body cells are vibrating in your body right now. They create four basic tissue types and 11 organ systems. All of these parts and pieces create an integrated whole called the human body. CELL TO SYSTEM Telomeres Telomeres are like caps on the tips of chromosomes. With aging, telomeres tend to shorten. Studies on the cutting edge of molecular biology have shown that a yogic lifestyle (including asanas, meditation, social support, and a plant-based diet) seems to increase telomere length, which may have an impact on increased longevity and health. Atom These chemical building blocks contain protons, neutrons, and electrons. They bond together to make important molecules, such as water (H2O). Cell Cells are the smallest unit of life. Most cells contain a nucleus in the center, cytoplasm, and an outer layer called the cell membrane. Small functional units inside the cell are called organelles. Tissue Cells come together to form tissues, which are like unique fabrics. This specifically shaped tissue is located in the liver. Blood vessels Cell membrane is semipermeable outer layer Protons and neutrons are in the nucleus Liver cells are called hepatocytes Chromosome consists of coiled DNA strand Telomeres on tips of chromosome Electrons surround the nucleus CHROMOSOME STRAND OF DNA A gene is a unit of DNA in a cell nucleus—meditation may prevent cellular aging and harmful gene expression DNA contains the information a cell needs to function and replicate US_010-011_Cell_to_system.indd 10 05/12/2018 12:06 11 Integumentary system The integumentary system includes hair, nails, skin and associated structures like sweat glands. Some claim that hot yoga causes you to “sweat out toxins.” However, your liver is responsible for such detoxification processes. What you are actually sweating out is water, leading to dehydration. If you sweat a lot or practice hot yoga, make sure you drink plenty of water to replenish your losses. SKIN The skin has two main layers: the epidermis on the surface and the dermis below, which contains sweat glands, blood vessels, nerves, and hair follicles. Human body Organ systems come together to form an organism. As a human being, you are made up of all of this, functioning as a dynamic, living whole. Arrector pili made of muscle tissue Tactile nerve made of nervous tissue Hair Organ Tissues come together to form organs, like your liver (shown below). This large organ receives blood from all over your body for processing and purification. It also makes bile, which is used to break down fats in the digestive process. System Organs come together to form organ systems, including: integumentary, skeletal, muscular, nervous, endocrine, respiratory, cardiovascular, lymphatic, digestive (shown above), urinary, and reproductive. Digestive system absorbs nutrients and eliminates waste products Liver forms part of the digestive system Liver has two lobes Sweat gland Blood vessel Nerve Dermis made of connective tissue Epidermis made of epithelial tissue US_010-011_Cell_to_system.indd 11 05/12/2018 12:06 12 HUMAN ANATOMY The 206 bones that make up your skeleton are dynamic, living organs. Together they form a framework for your body that provides structure and protection, and has the ability to move. SYSTEM OVERVIEW Your bones are made of collagen and they store calcium, a mineral that makes them strong and is vital for bodily functions. They also contain bone marrow where blood cells are produced. Bones form joints, which are supported by cartilage and structures such as ligaments. Yoga can support your bone and joint health. SKELETAL SYSTEM Bone structure Bone has a smooth outer connective tissue shell called periosteum. Inside this is a strong, dense layer known as compact bone. Deeper still is spongy bone with honeycomblike spaces; this is strong yet light. Mandible Lower jawbone that forms the only movable joint in your skull Clavicle Also called the collar- bone, it connects your scapulae and sternum Carpals Eight small bones form each wrist Metacarpals Five long bones run through each palm Phalanges Each hand has 14 bones forming your fingers Sternum Also called the breastbone, it connects your ribs Ribs The 12 pairs of bones that form your ribcage Pelvis Two hip bones connected by your sacrum Tarsals The seven small bones that form your ankle Patella Also called the kneecap, it is attached to your quadriceps tendon Metatarsals Five long bones that run through your foot Phalanges The 14 bones in each foot that form your toes Skull These fused plates of bone protect your brain Periosteum Compact bone Bone marrow Spongy bone US_012-013_Skeletal_01.indd 12 02/11/2018 14:00 13 Cartilage Hyaline articular cartilage lines bones at most joints and is smoother than glass—it even looks like stained glass under a microscope. However, when this cartilage wears down, it can become coarse like sandpaper, causing a condition called osteoarthritis (see p.17). Ligaments Bones are connected by dense fibers called ligaments. Both ligaments and tendons (see p.19) have very little elasticity, meaning, if you overstretch them in an asana, they often don’t go back to their resting length and lose stability. Vertebral column A series of bony disks that form your spine Scapula The shoulder blade connects torso and arm Humerus This bone connects your scapula and forearm Sacrum This bone is the keystone of your pelvis Ulna Forearm bone that runs to your little finger Radius Forearm bone that runs to your thumb Femur Your thighbone is the longest bone in your body Tibia You can feel the edge of your shinbone under your skin Fibula Thin bone that sits on the outside of your leg Calcaneus Your heel bone attaches to your Achilles tendon Ligament attaches bone to bone Chondrocyte (cartilage cell) US_012-013_Skeletal_01.indd 13 02/11/2018 14:00 14 SPINE Your vertebrae sit on top of each other to create natural curves. This is called a “neutral spine.” It alternates between curving inward (lordosis) and outward (kyphosis) to absorb shock like a coiled spring. Your vertebrae are like wedges stacked to form these curves in order to bear your body weight most efficiently. Cervical curvature There is a natural lordosis in the neck Thoracic curvature There is a natural kyphosis in the mid-back Lumbar curvature There is a natural lordosis in the lower back NEUTRAL SPINE These natural curves create the strongest, most stable alignment of the spine. In this ideal, the spine is also not twisted or leaning to either side. KYPHOSIS Hyperkyphosis of the thoracic spine is often simply called a kyphosis or hunchback. This exaggerated curvature is common in osteoporosis. LORDOSIS Hyperlordosis of the lumbar spine is sometimes just called a lordosis or swayback. This exaggerated curvature is natural during pregnancy. Neutral spine Many asanas incorporate a neutral spine, such as seated meditation poses. Poor posture and other considerations can lead to a multitude of spinal structural deviations, including common conditions like hyperlordosis and hyperkyphosis. Yoga works your spine in unique ways and enhances body awareness to improve your overall posture. THORACIC VERTEBRA LUMBAR VERTEBRA CERVICAL VERTEBRA Gentle, even curves Curvature in upper spinal column Curvature in lower spinal column Space for vertebral artery Hole for spinal cord Body of vertebra Articulates with rib Enlarged body to support weight Articular process US_014-015_Skeletal_02.indd 14 02/11/2018 14:00 15 HUMAN ANATOMY Skeletal System PELVIS Your pelvis includes two hip (coxal) bones connected by your sacrum. The sacrum, which means “sacred” in Latin, is the triangular bone with the tailbone at the lower, or inferior, end; it acts like the keystone to an arched bridge, forming a structurally sound base for your spine. Acetabulum The socket of your hip joint which articulates with your femur Coccyx These fused bones are known as the tailbone Pubic symphysis This joint is made of fibrocartilage like your intervertebral disks Sacroiliac joint Commonly called the SI joint, this is slightly movable Ischial tuberosity Your “sitting bones” are at the base of your pelvis Greater sciatic notch This creates a space for the sciatic nerve to pass Neutral pelvis A neutral pelvis facilitates a neutral spine and vice versa. Imagine your pelvic bowl filled with water. Finding a neutral spine and pelvis means that the water wouldn’t spill backward, forward, or to the side— such as when one of your hip points is lifted or your pelvis is rotated. Anterior superior iliac spine Your “hip points” can be felt under your skin FEMALE PELVIS POSTERIOR TILT Pelvic bowl tilts backward, flattening lumbar curve NEUTRAL Pelvic bowl is balanced, with neutral lumbar curve ANTERIOR TILT Pelvic bowl tilts forward, exaggerating lumbar curve US_014-015_Skeletal_02.indd 15 02/11/2018 14:00 16 JOINTS Joints are where bones unite and articulate to allow movement. There are three joint types: fibrous, cartilaginous, and synovial. Fibrous joints are immobile, such as the sutures in your skull. Cartilaginous joints are slightly mobile, like your pubic symphysis. Synovial joints are most mobile and are very important for asanas. Inside a joint Synovial fluid lubricates and cushions. It is a “non-Newtonian fluid,” which means it gets more viscous or thicker in response to pressure, similar to solutions of cornstarch in water. With a sedentary lifestyle, synovial fluid may become thin and less effective. However, impact from the practice of yoga asanas causes synovial fluid to thicken, reducing pain and better protecting joint structures such as cartilage. JOINT ACTIONS Synovial joints of your body can move in many directions. Hinge joints in your elbow and knee mainly perform flexion and extension, like the hinge of a door. Larger ball and socket joints like in your shoulder and hip can also perform abduction, adduction, rotation, and circumduction, which is a combination of all of the above movements. SYNOVIAL JOINT Synovial joints allow movement while protecting bone ends from touching each other, which would cause damage. They are the most common type of joint in the body. ELBOW JOINT TRIANGLE Hip external rotation Hip internal rotation and abduction Elbow extension Shoulder abduction Spinal axial rotation Ligaments connect bone to bone Bones come together to create a joint Spongy bone Healthy synovial fluid is thick to cushion joint Articular cartilage reduces friction Joint capsule holds joint together Knee extension Shoulder external rotation TYPES OF MOVEMENT Flexion Angle at joint generally gets smaller Extension Angle at joint generally gets larger Abduction A limb moves away from the body Adduction A limb moves closer toward the body External rotation A limb rotates outward Internal rotation A limb rotates inward Axial rotation The spine twists on its axis Plantar flexion Pointing the feet Dorsiflexion Flexing the feet US_016-017_Skeletal_03.indd 16 02/11/2018 14:01 17 HUMAN ANATOMY Skeletal System HEALTHY JOINT LATE ARTHRITIS EARLY ARTHRITIS Arthritis Wear and tear on joints can lead to osteoarthritis. In a 7-year clinical trial, researchers found that yoga is safe and effective in managing both osteoarthritis and rheumatoid arthritis (see p.37). After an 8-week yoga class, participants showed a reduction in pain by 25 percent, along with statistically significant improvements in physical fitness and quality of life. THE POSES Yoga asanas move joints in all directions. Visualize or try doing these poses to experience the joint actions in your body. Imagine or feel each joint action internally. CHILD’S POSE DANCER Knee flexion Hip flexion Spinal flexion Hip flexion and adduction Shoulder internal rotation Hip extension Knee extension Shoulder external rotation Ankle dorsiflexion Ankle plantar flexion Shoulder extension Knee flexion Spinal extension Smooth cartilage Synovial fluid cushions joint Space in joint Cartilage degrades Joint space narrows Bone spur Bone surfaces meet Cyst in bone Inflamed membrane PROGRESSION As cartilage degrades there is less space in the joint, leading to inflammation and pain. Bone spurs or osteophytes can form as the condition progresses. US_016-017_Skeletal_03.indd 17 02/11/2018 14:01 18 HUMAN ANATOMY There are about 640 muscles in your body. Your skeletal muscles are attached to your bones, allowing you to move. Some muscles are superficial (close to the surface) and others are deep. SYSTEM OVERVIEW As you study each of these key chosen muscles, try to palpate or physically touch them while visualizing their internal location. This will help you learn better, while improving your mind-body connection. Most of the muscles here are categorized into groups based on their actions. MUSCULAR SYSTEM Pectorals Pectoralis major Pectoralis minor Elbow flexors Biceps brachii Brachialis (deep) Brachioradialis Intercostal muscles Abdominals Rectus abdominis External abdominal obliques Internal abdominal obliques (deep, not shown) Transversus abdominis Ankle dorsiflexors Tibialis anterior Extensor digitorum longus Extensor hallucis longus Brachialis Hip flexors Iliopsoas (iliacus and psoas major) Rectus femoris (see quadriceps) Sartorius Adductors (see below) Adductors Adductor longus Adductor brevis Adductor magnus Pectineus Gracilis Quadriceps Rectus femoris Vastus medialis Vastus lateralis Vastus intermedius (deep, not shown) Skeletal muscle There are three types of muscle tissue: cardiac, smooth, and skeletal. We will focus on skeletal muscle as it is responsible for the movement of joints in asana. This is what it looks like under a microscope. Striations are visible stripes from internal structures (see p.21) Muscle fibers are arranged in parallel orientation DEEPSUPERFICIAL US_018-019_Muscular_01.indd 18 25/09/2018 17:03 19 Trapezius Rhomboids Rhomboid minor Rhomboid major Cervical extensors Splenius capitis Splenius cervicis Gluteus medius Hip extensors Gluteals Adductor magnus Hamstrings Biceps femoris Semitendinosus Semimembranosus Deltoids Spinal extensors Cervical extensors (above) Erector spinae Transversospinales (small, deep muscles along spine) Gluteals Gluteus maximus Gluteus medius Gluteus minimus Latissimus dorsi Triceps brachii Piriformis Hip flexors Iliopsoas (iliacus and psoas major) Rectus femoris (see quadriceps) Sartorius Adductors (see below) Muscle has more blood flow and stretching capacity DEEP SUPERFICIAL Levator scapulae Serratus posterior Ankle plantar flexors Tibialis posterior Calf muscles Gastrocnemius Soleus Adductor magnus Tendons Tendons are tough cords of dense connective tissue attaching muscle to bone. As bundles of parallel collagen fibers, they have little elasticity or blood flow. In general, you want to stretch muscles, not tendons. Collagen fibers resist pull or tension US_018-019_Muscular_01.indd 19 25/09/2018 17:03 20 Fascicle A bundle of muscle cells Muscle cell Also called a muscle fiber Myofibril Microscopic contractile proteins M line Middle of a sarcomere PLANTAR FASCIA TYPES OF CONTRACTION Isotonic contractions involve a change in muscle length, as in the act of flexing or extending your elbow (see below) or transitioning in or out of an asana. Isometric contractions involve tension with no change in muscle length, such as when holding an asana. ECCENTRIC CONTRACTION Eccentric contractions occur when muscle fibers “lengthen” to change the angle of a joint. This occurs in your biceps when extending your elbow as you lower a weight, or in your hamstrings when extending your knee as you transition from Warrior II to Triangle (see pp.118–21) pose. MUSCLE STRUCTURE Skeletal muscles are bundles of bundles of bundles of parallel muscle cells, blood vessels, and nerves wrapped with connective tissue, including fascia. Fascia creates a network through and around muscles and other structures of your body. Microscopic proteins in your muscles cause muscle contractions. HOW MUSCLES WORK Muscles often work in antagonistic pairs. As the agonist muscle engages, the antagonist generally releases. Synergist muscles engage around the joint to support the action. Z disk Edge of a sarcomere Thin filament Made of the protein actin Thick filament Made of the protein myosin Fascia Fascia is similar to the white pith of an orange; it separates parts yet integrates the whole. Fascia is not just found around muscles. It is also around vital organs and woven throughout your body. This body-wide network of fascia is part of the reason why a yoga pose that affects your foot can suddenly release your tight shoulders. Fascia connects heel to toes Flat band of connective tissue Extension Angle of joint increases Antagonist Biceps brachii is the antagonist as it mostly relaxes Agonist Triceps brachii is the agonist as it concentrically contracts to extend the elbow US_020-021_Muscular_02.indd 20 04/12/2018 12:00 21 Flexion Angle of joint decreases Agonist Biceps brachii is the agonist as it concentrically contracts to flex the elbow CONCENTRIC CONTRACTION Concentric contractions occur when the muscle fibers “shorten” to change the angle of a joint. This occurs in your biceps when flexing your elbow as you lift a weight, or in your hamstrings when flexing your knee as you move into Warrior II (see pp.102–05). CONTRACTED SARCOMERE RELAXED SARCOMERE Muscle contraction A cascade of events initiated by a signal from the nervous system and the presence of calcium leads to the removal of the blockage on actin of the thin filament, allowing the thick and thin filament to connect. The thick filament pulls the thin filament in toward the M-line, bringing the Z-disks closer together. COLLAGEN FIBERS Thick filament Thin filament M line Z disk Antagonist Triceps brachii is the antagonist as it mostly relaxes HUMAN ANATOMY Muscular System Movement and fascia Research suggests that the collagen fibers of the fascia surrounding healthy muscles are organized in a crisscross, lattice structure. Inactivity and aging seem to cause your fascia to lose its structural integrity. Asana may help organize your fascia, helping you move and feel better. Healthy double lattice collagen orientation Random collagen orientation from inactivity US_020-021_Muscular_02.indd 21 04/12/2018 12:00 22 HUMAN ANATOMY The nervous system is a control network that connects all body systems. It is split into the central and peripheral nervous systems (PNS). The PNS is comprised of the somatic and autonomic nervous systems. SYSTEM OVERVIEW The somatic nervous system consists of nerves carrying sensory and motor signals to and from the spinal cord and brain. The autonomic nervous system (ANS) is divided into two functional systems: the sympathetic nervous system and parasympathetic nervous system, which accounts for many of yoga’s benefits. NERVOUS SYSTEM Brain Responsible for control and cognition Spinal cord Your body’s primary communication highway Brachial plexus A collection of nerves around your armpit Sciatic nerve Largest nerve in your body Cranial nerves 12 pairs of peripheral nerves Ulnar nerve On the little finger side, causes tingling when hitting “the funny bone” Femoral nerve Supplies sensation around thigh and leg Tibial nerve Branches off sciatic nerve Digital branches of fibular nerve Supply sensation to foot Spinal cord In this superior, or bird’s-eye, view of a vertebra, you can see how your spinal cord is protected by the bony encasement of the spinal column. Spinal nerves project off to the side, in between the vertebrae. Spinal cord connects the brain and bodySpinal nerve carries messages to and from your central nervous system Vertebra protects spinal cord Median nerve Can be pressed on in carpal tunnel Lumbar plexus A collection of nerves around lower back Sacral plexus A collection of nerves around your sacrum US_022-023_Nervous_01.indd 22 02/11/2018 14:01 23 NERVE STRUCTURE Neurons are the main cells of your nervous system. Axons are bundled together in your PNS to make nerves. Nerves are like highly conductive electrical wires sending signals throughout your body. Some are wrapped with a fatty substance called myelin, making their signals travel faster. Cell body Contains nucleus Dendrite Smaller projections that receive signals from neighboring neurons Myelin Covering that insulates and speeds up signal Epineurium Connective tissue around nerve Perineurium Connective tissue around bundle of neurons Endoneurium Connective tissue around neuron Axon Largest projection that transmits signal to next cell NERVE SIGNAL Nerve signals are pulses of electricity along the cell membrane due to the movement of electrically charged particles called ions. NERVE NEURONS THE AUTONOMIC NERVOUS SYSTEM The autonomic nervous system (ANS) can be thought of as your body’s autopilot. Its functions are automatic and they include processes such as your heart rate, breathing, digestion, and excretion, which happen without you having to consciously think about them. The ANS is further divided into two systems of control that complement each other: the sympathetic nervous system (SNS) and the parasympathetic nevous system (PSNS). Stimulates proper digestion Stimulates glucose storage as glycogen Slows heartbeat Constricts airways Constricts pupils Stimulates pancreatic enzyme release Stimulates peristalsis Contracts bladder Constricts blood vessels Slows urine output Accelerates heartbeat Inhibits proper digestion Inhibits peristalsis (see p.39) Relaxes bladder PARASYMPATHETIC NERVOUS SYSTEM The PSNS is known as “rest and digest” or the “relaxation response” because it creates a restful state of optimal function. SYMPATHETIC NERVOUS SYSTEM The SNS is known as “fight or flight” or the “stress response” because it helps you deal with stressful situations. Dilates pupils Nerve signal Brain and spinal cord monitor internal conditions of body Dilates airways Stimulates glucose production US_022-023_Nervous_01.indd 23 28/09/2018 12:36 24 CEREBRAL CORTEX Compared to other mammals, our brains are massive for our bodies, with a particularly developed cerebral cortex. Most of the cortex is on the outside of the brain, except the insula. It is composed of gray matter, which is filled with synapses or connection points between neurons. Your cortex has five lobes and many functional areas. INSIDE THE BRAIN The brain contains many different structures and scientists are still figuring out what their functions are. Some of these structures monitor conditions inside your body and relay information. The limbic system is the emotional center of your brain. LOBES OF THE BRAIN The brain is separated into five main divisions, called lobes, including the insula which is inside the brain (not seen here). INTERNAL STRUCTURES This image shows the brain as if it were cut in half down the middle (a midsagittal section) to reveal structures inside the cerebrum. Parietal lobe Processes body sensation Occipital lobe Back area of the cortex processes vision Frontal lobe Responsible for decision-making and motor functions Temporal lobe Involved in smell, hearing, and memory Corpus callosum Connects two sides of brain Hypothalamus Controls much of neuroendocrine function Thalamus Relay center for information LATERAL VIEW MIDSAGGITAL SECTION US_024-025_Nervous_02.indd 24 02/11/2018 14:01 25 How yoga affects your brain This chart looks at the neuroscience that may explain the vast mental and physical benefits of yoga. Modern science shows us that the brain maintains its ability to adapt across a lifetime, making it possible to break bad habits and negative patterns. It can also create the key chemicals that pharmaceutical companies synthesize in a lab. Research is uncovering the huge potential of yoga therapy to help people on a global scale. These effects stem from yoga’s multidimensional approach, reflected in its 8-limb structure (see p.198), which includes guidelines on self-control and self-regulation. Cerebellum Involved in bodily movement, muscle control, and balance Hippocampus Memory center that allows neurogenesis (see pp.26–27) Brainstem Regulates autonomic functions like breathing and heart rate Olfactory bulb Detects scents and triggers memories Amygdala Fear center Pons Communication center on brainstem Cingulate gyrus Regulates emotions and behavior Caudate nucleus Involved in learning and processing memories Fornix Plays a role in memory processing Putamen Involved in movement and learning Pineal gland Regulates sleep–wake cycle LIMBIC SYSTEM Brain alpha wave activity increased Alpha waves are associated with relaxation. GABA increased Gamma-aminobutyric acid counteracts anxiety and stress symptoms, leading to more relaxation. Serotonin increased Serotonin helps regulate your mood. Low levels of usable serotonin are associated with depression. BDNF increased Brain-derived neurotrophic factor is a protein responsible for neuron health and neuroplasticity. Yoga can boost levels of BDNF, which may help people with chronic pain or depression. Cortisol reduced Cortisol is a stress hormone. When your baseline increases and levels are too high for too long, it can lead to inflammation and weight gain. Norepinephrine reduced A decrease in norepinephrine, or adrenaline, means fewer stress hormones in your system. Dopamine regulated Dopamine acts as your body’s reward system and dysfunction is associated with addiction. Research suggests that meditation results in improved self-regulation. HUMAN ANATOMY Nervous system US_024-025_Nervous_02.indd 25 02/11/2018 14:01 26 NEURAL PATHWAYS The brain develops neural connections—and eventually becomes conditioned—based on your choices and experiences. It is said that neurons that fire together, wire together. The more you practice an activity—or a mindset—the more networks are created. With approximately 100 billion neurons, the brain’s possible connections are vast. Yoga practices facilitate this process. CHANGING BRAIN Neuroplasticity is the ability of your brain to be molded. Not long ago, scientists thought the brain couldn’t change after childhood and degraded with age. Now we know that nervous tissue adapts. Like exercise affects your muscles, your brain tissue either develops or atrophies based on stimulation. BUILDING A NETWORK Repetition strengthens and continues to build a neural network. BUILDING CONNECTIONS A new experience triggers neurons to form new connections. More cells join network Nerve signal Nerve signal New connection Brain cell New connection Synapse CYCLIC NATURE OF HABITS UNSTIMULATED BRAIN Without stimulation, fewer connections are made. The brain tissue looks like a dying tree with sparse branches. STIMULATED BRAIN With stimulation, more connections form. The brain tissue looks like a thriving tree with dense branches. VRITTI (THOUGHT PATTERN) KARMA (ACTION) How yoga boosts your brain There is no neuroplasticity pill. The most effective way to shape your brain is through behavioral changes. Although any yoga practice should encourage neuroplasticity, try the tips here for improved results. Samskara Yogis perhaps conceptualized neuroplasticity with samskaras: impressions due to past thoughts and actions. Yoga can help beat bad habits or conditioned responses by affecting neural pathways and samskaras. This occurs at a synaptic level each time you consciously change your thoughts and actions through awareness and practice. The more you travel that new path, the stronger the connection between the neurons gets. Increase the intensity Moderate to vigorous physical activity, like from sun salutations, is one of the most effective ways of increasing brain-derived neurotrophic factor. This is a nerve growth factor, which is like a glue that helps to wire in neural connections. Change your routine Purposefully and consciously changing your yoga practice routine benefits your mind and your body. Join a class The act of moving with a group and following the teacher activates mirror neurons. The mirror neuron system is a recently discovered network of nerves involved in emulation of movement and developing compassion. Meditate Research shows that meditation builds gray matter in your cerebral cortex. SAMSKARA (IMPRESSION) US_026-027_Nervous_03.indd 26 28/09/2018 12:36 27 HUMAN ANATOMY Nervous System Hippocampus (Memory) Amygdala (Fear) Hippocampus Amygdala PADMA MUDRA HAKINI MUDRA SHUNI MUDRA BUDDHI MUDRA NEUROGENESIS Scientists used to think that people are born with a certain number of nerve cells and that they cannot grow new ones. Research has since revealed that the growth of new neurons, or neurogenesis, can happen at any age. Neurogenesis occurs in key areas of the brain responsible for memory—the hippocampus—and smell. Neural stem cells in these regions of the brain develop new neurons. SITE FOR NEW CELLS In this hippocampus tissue, helper cells or neuroglia are blue, axons are green, and neuron cell bodies and stem cells are pink. Stem cells Hippocampal stem cells can develop into new neurons, improving memory CORTISOL LEVELS Consistently high levels of the stress hormone cortisol are related to increased amygdala (fear center, see p.25) activity and decreased hippocampal (memory center) activity. When under these conditions, the hippocampus doesn’t grow new neurons or connections well. Yoga practices are shown to reduce cortisol levels and reverse these effects, which may contribute to improving memory. STRESS AND MEMORY Increased activity in the amygdala is correlated with reduced activity in the hippocampus, which has an adverse effect on memory. Practice hand mudras Hand mudras are gestures that require concentration and awareness. Just as people who read braille have more developed hand-specific sensory areas of their brain, mudras may develop brain areas linked with sensory acuity, and fine motor skills. US_026-027_Nervous_03.indd 27 28/09/2018 12:36 28 HUMAN ANATOMY The endocrine system is a slower, longer- lasting control system than the nervous system. It consists of glands that release hormones into your bloodstream to be delivered to specific cells. SYSTEM OVERVIEW Your brain controls the release of hormones from endocrine glands to maintain a balance inside your body, called homeostasis. Stressors—from external environmental conditions to internal or emotional factors—affect this balance, but yoga can help. For example, research suggests that yoga may prevent and improve symptoms of type 2 diabetes. ENDOCRINE SYSTEM HypothalamusControls other glands Pituitary gland Produces key hormones Small intestine Releases hormones to help with digestion Testis Produces male sex hormones Parathyroid gland Regulates blood calcium levels Thyroid gland Regulates metabolism and blood calcium Pancreas Secretes insulin and glucagon to regulate blood sugar Pineal gland Makes melatonin, which affects sleep FEMALE MALE Ovaries produce female sex hormones Adrenal gland Regulates salt levels and produces adrenaline in response to danger Heart Releases hormones to regulate blood pressure US_028-029_Endocrine.indd 28 28/09/2018 12:36 29 Most breathwork can lower metabolism Meditation has been shown to lower metabolism Islet Beta cells in pancreas release insulin Your thyroid regulates metabolism Pancreatic islets Inside your pancreas, islets contain different types of cells. Beta cells release insulin, which allows your body cells to use glucose. Homeostasis and allostasis Homeostasis is your body’s state of dynamic equilibrium. Most processes— like the control of hormone release, blood calcium and blood sugar levels, and temperature—are tightly regulated through negative feedback, which works in a similar way to a thermostat. Nature wants you to be in balance. Yogis referred to this as samatva, which can be translated as equilibrium or equanimity. Allostasis is a process of maintaining homeostasis amid stressors. The more intense the stress, the heavier the “allostatic load” and the more your cells have to work to maintain equilibrium. This increases the likelihood of chronic diseases. Researchers believe that yoga can reduce allostatic load. Metabolism Most yoga practices tend to slow your metabolism, which helps your body to be more efficient with less. Although your metabolism may slightly lower from relaxation- based practices, this doesn’t mean you will gain weight. A reduction in stress hormones like cortisol also prevents your body from holding onto fat. PANCREAS Your pancreas releases insulin to help sugar get into your body cells. However, cells can become insulin- resistant, which can cause disease. A review found that yoga can improve glycemic control, lipid levels, and body composition of fat in those with metabolic syndrome and type 2 diabetes. A doctor-approved reduction in medications was also found. 500lb 500lb 5lb 5lb INCREASED LOAD REDUCED LOAD Low blood levels of hormone detected Gland decreases secretion of hormones Hormone production by gland turned down Hormone production by gland turned up Gland releases more hormone into the blood Rising blood levels of hormone detected HOMEOSTASIS ALLOSTASIS US_028-029_Endocrine.indd 29 02/11/2018 14:01 30 HUMAN ANATOMY You take a breath 12–20 times per minute. The purpose of your breath is to get oxygen to your cells and to get rid of waste like carbon dioxide. The respiratory system includes the nasal cavities, air passageway tubes, and lungs. SYSTEM OVERVIEW You don’t have to think to breathe; respiration is a part of your autonomic nervous function. However, yogis claim that by controlling your breath, you can control all aspects of being. Science reveals that your breath is an access point to regulating your nervous system. RESPIRATORY SYSTEM Neti pots The neti pot is a part of traditional yogic hygiene practices. It involves pouring clean (filtered or boiled), warm salt water in one nostril to fill the sinuses and drain out the other nostril. Neti pots (or a similar sinus rinse) are recommended by many modern physicians to help allergies and respiratory illness. Frontal sinus Maxillary sinus Nasal passageway Diaphragm Primary muscle of respiration Lungs Branching airways end here; oxygen enters blood and carbon dioxide is removed Larynx Top part of trachea, contains vocal cords Trachea Also called the windpipe, carries air to lungs Mouth Air can enter here, though less efficient Nostril Openings in the nose Epiglottis Flap that closes off trachea to keep food from entering airways Nasal cavity Air entering through nose is humidified, warmed, and filtered SINUSES Your sinuses are a system of connected, air-filled cavities in your skull. They make your skull lighter, help your voice to resonate, and affect your breath. Sphenoid and ethmoid sinuses US_030-031_Respiratory_01.indd 30 06/11/2018 10:18 31 HOW WE BREATHE When you inhale, the breath enters your nose, throat, and then your lungs. Your lungs and ribcage expand three- dimensionally in all directions; your diaphragm engages to flatten. When you exhale, your diaphragm relaxes to ascend, your lungs and ribcage compress, and the air releases out of your throat and then nose. Belly breathing “Belly breathing” doesn’t mean you are actually breathing in your belly, but rather that you are allowing your belly to move freely with your breath. When your diaphragm engages with the inhale, it presses against your abdominal organs— pushing down and out, which is why this is also called diaphragmatic breathing. Ribcage expands, creating space in chest Air drawn in through nose or mouth Air expelled through nose or mouth Ribcage releases down and in Diaphragm Lumbar vertebrae attach to diaphragm Ribs attach to diaphragm Ribcage Bones surrounding lungs INHALE EXHALE INFERIOR VIEW Lungs enlarge, filling with air Lungs decrease in size, pushing out air Diaphragm contracts, allowing lungs to descend Diaphragm relaxes and expands US_030-031_Respiratory_01.indd 31 28/09/2018 12:36 32 PRANAYAMA Yogis use pranayama or breathwork to control their prana and anchor to the present moment. The word prana in Sanskrit means vital energy or life- force energy that permeates through us and everything. Interestingly, prana simultaneously means breath. Yogis believe that you can change the flow and qualities of your energetics by breath control. INHALE AND EXHALE When you inhale, blood is shunted to your heart and lungs to help them function. Baroreceptors (see p.134) sense this increased pressure and respond by signaling to let off the brake pedal, momentarily increasing sympathetic activity. During each exhale, your heart is slightly more relaxed with increased parasympathetic activity. This explains why elongating your exhales in pranayama is relaxing. Brain stem Automatically monitors breathing Vagus nerve Increases parasympathetic nervous system (PSNS) activity with exhales Baroreceptor Pressure receptors located here INHALE EXHALE Sympathetic nerve Increases sympathetic nervous system (SNS) activity with inhales Heart Relaxes slightly with exhale BREATHWORK PRACTICES Modern yogis use breathwork for health benefits, including overcoming inefficient breathing patterns from a culture of poor posture and stress. Through altering your breath, you change your state of mind. For example, you may practice left nostril breathing and bee breath to calm down or right nostril breathing and kapalabhati for alertness. Active exhale Quick, forceful exhale pushes air out Passive inhale Pressure passively allows air in Abdominals move gently outward Chest expands Abdominals drawn in Ribs drop in BREATH OF FIRE (KAPALABHATI) This is a fast breath that mimics hyperventilation, increasing your heart rate and blood pressure. It also tones your abdominals. Avoid this technique if you are pregnant or have anxiety, certain eye conditions, or high blood pressure. Similar effects and precautions apply for holding your breath (kumbhaka). US_032-033_Respiratory_02.indd 32 28/09/2018 12:37 33 HUMAN ANATOMY Respiratory System Vagus nerve Increases parasympathetic nervous system (PSNS) activity with exhales Left brain, right brain Each half of your body is controlled by the opposite hemisphere of your brain—meaning that your left arm is controlled by the right half of your brain. The same is true of your nostrils. This may have many implications, including a slight overall increase in SNS activity when right nostril breathing and PSNS when left, although evidence is mixed. BRAIN HEMISPHERES OPEN PARTIALLY CLOSED Right nostril breathing, alert and energetic Left brain, increased SNS activity Right brain, increased PSNS activity NASAL CYCLE For many, each nostril takes turns dominating air flow (in .5- to 4-hour shifts). This is called the nasal cycle. You probably notice this more when you are congested. Openness indicates local vasoconstriction and the swollenness indicates vasodilation. Observe this cycle naturally or try purposefully covering one nostril for a desired effect (see panel right). NASAL TISSUE This image shows the right nasal passage swollen while the left is open. In this case the swelling is exacerbated by congestion. VICTORIOUS BREATH (UJJAYI) Victorious breath involves partially constricting your vocal cords. The feeling is similar to when you whisper softly. It creates an ocean sound to give your mind a focal point. BEE BREATH (BRAHMARI) This involves covering your eyes and ears and humming on a long exhale. Yogis used this to improve sleep. Research shows it can lower heart rate, blood pressure, and anxiety. Finger blocks one nostril Fingers and thumbs cover ears and eyes ALTERNATE NOSTRIL BREATHING This technique may calm the mind and body. It involves focus and activation of both sides of the brain. To practice it, just remember: exhale, inhale, and switch nostrils. Vocal cords during normal breathing Vocal cords during ujjayi Left nostril breathing, calm and relaxed Thumb switches to block other nostril Open nasal passage Engorged nasal tissue Maxillary sinus US_032-033_Respiratory_02.indd 33 28/09/2018 12:37 34 HUMAN ANATOMY The heart, an intricate network of vessels, and the blood circulating through them make up your cardiovascular system. SYSTEM OVERVIEW Your heart constantly beats to pump blood around your body, removing waste and delivering vital oxygen. Research on yoga suggests profound benefits for cardiovascular health, including a reduced risk of heart disease. Yoga has been shown to clinically improve blood pressure, cholesterol levels, and cardiovascular resilience (see opposite). CARDIOVASCULAR SYSTEM Composition of blood Adults have about 11 pints (5 liters) of blood circulating around the body. Blood is a connective tissue composed of red blood cells, white blood cells, and platelets suspended in a liquid called plasma. It provides oxygen, nutrients, and hormones, as well as removing waste from cells. Platelets Also called thrombocytes, they help blood to clot Red blood cells Also called erythrocytes, they deliver oxygen White blood cells Also called leukocytes, they fight invaders Jugular vein Returns blood from brain to heart Femoral vein Delivers blood from lower limbs to heart Femoral artery Carries blood to thighs Popliteal artery Carries blood to knee and calf Great saphenous vein Longest vein in the body Subclavian artery Carries blood to arm and hand Carotid artery Delivers blood to brain Superior vena cava Returns blood back to heart Aorta Largest artery in your body Heart Muscular pump for blood Inferior vena cava Returns blood from lower body to heart Abdominal aorta Delivers blood to abdomen and lower body US_034-035_Cardio_01.indd 34 28/09/2018 12:37 35 Heart rate variability Heart rate variability (HRV) is the heart’s ability to adapt fast. It is better for your pulse to vary rather than tick steadily. High HRV shows autonomic resilience and may lead to improved physical, emotional, and cognitive function. Yoga appears to improve HRV. Hypertension Research shows that yoga can reduce blood pressure significantly. With more than 1 billion people living with hypertension, yoga offers a cost-effective adjunct to care with minimal to no side effects. Consult your doctor about any blood pressure shifts. Cholesterol Reports have shown that yoga can increase “good” cholesterol (high-density lipoprotein or HDL) and decrease “bad” cholesterol (low-density lipoprotein or LDL). This reduces the risk of heart disease by preventing arterial narrowing. Heart disease A meta-analysis suggests that yoga reduces heart disease risk as well as or better than accepted exercise guidelines. Long-term clinical trials have shown that a yogic lifestyle— with asanas, meditation, social support, and a plant- based diet—could reverse heart disease. HEART AND CIRCULATION Circulation has two loops: pulmonary (lungs) and systemic (body). Veins carry blood to the heart, and arteries carry it away. Veins are shown in blue to represent deoxygenation, and arteries are red for oxygenation. The exceptions are pulmonary arteries (deoxygenated) and pulmonary veins (oxygenated). Cerebral arteries Deliver oxygenated blood to brain Pulmonary vein Returns oxygenated blood from lungs Capillaries Where exchange occurs Artery wall Thick muscular walls adjust pressure Cerebral veins Return deoxygenated blood from brain Pulmonary artery Delivers deoxygenated blood to lungs Vein valve One-way valves prevent backflow Vein Veins return blood to your heart from cells. The blood is usually deoxygenated (oxygen-poor). Artery Arteries carry blood away from your heart to cells. The blood is usually oxygenated (oxygen-rich). NARROWED ARTERY DAMAGED HEART TISSUE BLOOD PRESSURE MONITOR HEARTBEAT Carotid artery Delivers blood to brain US_034-035_Cardio_01.indd 35 28/09/2018 12:37 36 HUMAN ANATOMY The lymphatic and immune systems work together to fight invaders. Acute inflammation can be a helpful result of this internal war, such as when you have a cut. However, chronic inflammation is an underlying cause of many major diseases. SYSTEM OVERVIEW Lymph vessels collect and drain excess fluid from body tissues. They also carry immune cells around your body. Evidence suggests that yoga can help reduce chronic inflammation and it may boost immunity, helping you get sick less often and less intensely. Your body can heal itself, and yoga can help. LYMPHATIC SYSTEM Tonsils Help destroy bacteria or viruses that enter the nose or mouth Thoracic duct Lymph drains back into the heart through here Axillary nodes A concentration of lymph nodes under the arm Spleen Produces cells that fight infection Cisterna chyli Collects lymph from the lower half of the body Lymph node Lymph is processed and cleaned here Inguinal nodes A concentration of lymph nodes around the groin Lymph vessel Drains and transports lymph Lymphocytes, specialized white blood cells Lymph flows out of node Valve keeps lymph flowing in one direction Lymph node These are checkpoints that screen lymphatic fluid for foreign invaders. The cleaned fluid is returned to your blood. Movement in yoga asanas, particularly from sun salutations and inversions, can help facilitate lymph flow. US_036-037_Lymphatic.indd 36 28/09/2018 12:37 37 Damage to cartilage More cytokines means more inflammation Yoga has been shown to reduce cytokines, including: IL-1beta, TNF-alpha, IL6, and IL10 Finger joint inflamed with rheumatoid arthritis T-cell White blood cells White blood cells are like warriors fighting viruses, bacteria, and cancer cells in your body. Fragments of the invaders, called antigens, are presented so the warriors can strategically fight using the right antibodies and chemical messengers, called cytokines. Communication is key—miscommunication can lead to chronic inflammation. DENDRITIC CELL These present antigens, which the body recognizes as a foreign invader. They activate T-cells to do their job. MACROPHAGE Hungry hunter cells (see phagocytosis below) that also release cytokines to induce inflammation. B-CELL A type of lymphocyte that secretes antibodies, which are proteins specialized to fight specific antigens. T-CELL A type of lymphocyte that is activated to fight by the presentation of antigens. There are many specialized types. INFLAMED JOINT A cascade of events can lead to inflammation, joint damage, loss of function, and possibly pain. CYTOKINES These are inflammatory markers that encourage an immune response. PHAGOCYTOSIS Macrophages (white) patrol your body on alert for invaders (red) to engulf and eat, in a process called phagocytosis. INFLAMMATORY RESPONSE Inflammation often involves heat, pain, redness, and swelling due to a cascade of events where white blood cells fight invaders. In an autoimmune disease, they mistakenly fight body tissue. For example, rheumatoid arthritis (see below) can flare to cause local inflammation and body-wide inflammation. Macrophage Inflammation Blood vessel Healthy cartilage Lymph node Dendritic cell Antigen fragment B-cell releases antibodies Cytokines (inflammatory markers) Yoga and inflammation Yoga seems to help attenuate inflammation by reducing the stress response, which may reduce your disease risk. A review shows that yoga practice reduces cytokine count and therefore inflammation. Scientists hypothesize that a long-term, regular practice would be most effective. US_036-037_Lymphatic.indd 37 28/09/2018 12:37 38 HUMAN ANATOMY The digestive tract is a tube with selective membranes that control what gets into your body. Nutrients are absorbed and waste is expelled. SYSTEM OVERVIEW Food is broken down into absorbable units by your digestive system, from chewing in the mouth to chemical breakdown in the stomach and squeezing in the intestines. Nutrients enter the blood, and ultimately your cells. Yogis recognized that you become what you eat, equating the physical body (anamaya) with the “food body.” DIGESTIVE SYSTEM Mouth Entry point for food Teeth Grind food, making it easier to swallow Salivary glands Release saliva to start digestion Epiglottis Cartilage flap that blocks entry to trachea Pharynx Also called the throat Esophagus Muscular tube that pushes food down Liver Makes bile and processes nutrients and toxins Stomach Breaks down food by acid and churning Gallbladder Stores and releases bile Small intestine Digests and absorbs nutrients Large intestine Stores food and beneficial bacteria Appendix Stores extra beneficial bacteria Rectum Voluntary muscular release chamber Anus Exit point of feces 30sec Chewing in mouth 10sec Swallowing 2–4hr Churning in stomach 3–5hr Absorbing nutrients in small intestine 10–18hr Water absorbed in large intestine After 24–72hr Undigested waste leaves body Journey of food It is best to practice yoga asanas on an empty stomach. That may mean not eating a meal 2–4 hours before class. You may need to strategically plan a small snack, especially if you tend to have low blood sugar or other medical conditions. US_038-039_Digestive.indd 38 28/09/2018 12:37 39 Nervous system health affects gut health Gut health affects nervous system health Peristalsis Peristalsis is the involuntary smooth muscular movement of food through your digestive tract. It’s encouraged by the relaxation response and physical movement, as from yoga asana practice. Gut brain About 95 percent of your serotonin, a chemical needed for mood regulation, is stored in and partially controlled by your gut. “Gut brain” or enteric nervous system (see right) dysfunction is associated with gastrointestinal upset and irritable bowel syndrome (IBS), depression, and anxiety. Serotonin molecule NONHARM FOOD GUT–BRAIN CYCLE Enteric nervous system (ENS) Scientists have recently discovered the semi-independent enteric nervous system (ENS). These 100 million neurons may be responsible for you feeling butterflies in your stomach from love or having an intuitive gut feeling. Yoga enhances your mind-body connection, so you can feel what is going on in your gut clearly. This interconnection may explain how yoga can improve both your digestion and mood significantly. Ahimsa diet Yogis often make conscious choices about what they put into their body. An ahimsa diet is one of nonharm. For many, this means being a vegetarian to reduce the suffering of other animals. A largely plant-based diet reduces your risk of heart disease, cancer, and related major killers. Scientists project that a mostly vegetarian diet may reduce global mortality by 6–10 percent and cut food-based greenhouse gas emissions by 29–70 percent—a huge impact on the environment. Even small dietary changes like a Meatless Monday can make a big difference. Muscle contracts to push food along Direction of movementMuscle relaxes US_038-039_Digestive.indd 39 02/11/2018 14:01 40 Bulbospongiosus Transverse perineal INFERIOR VIEW OF FEMALE HUMAN ANATOMY The urinary system filters out waste and excess fluids to maintain correct blood volume. This, in turn, affects blood pressure, which yoga has also been shown to help regulate. SYSTEM OVERVIEW Your kidneys process waste from blood into urine, which is then stored in your bladder. Urine release is voluntary in adults but some people lose this control, leading to urinary incontinence. A recent study showed that yoga classes may help manage urinary incontinence. URINARY SYSTEM Abdominal aorta Delivers blood to kidneys and lower body Kidney Filters blood to make urine Inferior vena cava Returns blood from kidneys and lower body Adrenal gland Regulates fluid volume Ureter Carries urine from kidneys to bladder Bladder Stores urine Prostate gland Surrounds male urethra Urethra Carries urine from bladder out of body Urethra Shorter urethra increases chance of infectionsFEMALE MALE Ischiocavernosus External anal sphincter Pubococcygeus Pelvic floor muscles Your pelvic floor muscles are vital for bladder control. Common issues such as frequent, urgent, or painful urination, or slight leaking— such as when sneezing or laughing—may be helped by yoga exercises. For example, a gentle version of mula bandha (see p.153) and relaxation practices could improve pelvic floor health. Iliococcygeus US_040-041_Urinary_Repro_01.indd 40 28/09/2018 14:50 41 Abdominal aorta Delivers blood to kidneys and lower body Milk ducts Carry milk from glands to nipple Nipple Opening where a baby sucks milk Cervix Opening to uterus Fallopian tube Connects ovary to uterus Ovary Where eggs are stored and released Uterus Where a fertilized egg develops Vagina Muscular tube Kidney Filters blood to make urine Adrenal gland Regulates fluid volume Ureter Carries urine from kidneys to bladder Bladder Stores urine FEMALEMALE The reproductive system functions to help continue our species by sexual reproduction. Yoga may help aspects of reproductive health, including pelvic floor health. This may improve sexual satisfaction, and labor and delivery. SYSTEM OVERVIEW Yoga seems to indirectly address aspects of pelvic health, both urinary and reproductive, partly by promoting optimal breathing. It is also feasible that, because yoga helps manage stress, it can improve fertility and conception; although we need more research to confirm this. REPRODUCTIVE SYSTEM Inhale Respiratory diaphragm and pelvic floor descend Penis Transfers sperm into the vagina Testes Manufacture sperm and testosterone Exhale Respiratory diaphragm and pelvic floor ascend PELVIC FLOOR AND DIAPHRAGM Endometrium Uterus lining that thickens to receive an egg Pelvic floor motion A healthy pelvic floor is able to move through its full range of motion with your breath, following the movement of your diaphragm. Yoga practice may enhance neurological awareness, along with increasing strength, flexibility, and the relaxation of these muscles. This may improve your bladder, bowel, sexual, and reproductive health. BREATHING Your pelvic floor muscles descend as you inhale and ascend as you exhale. Pelvic floor muscles Respiratory diaphragm US_040-041_Urinary_Repro_01.indd 41 20/09/2018 21:18 SEATED Pages 44 – 83 STANDING Pages 84 – 121 INVERSIONS Pages 122 – 143 FLOOR Pages 144 – 173 US_042-043_Opener_AsanaSection.indd 42 21/09/2018 11:09 THE ASANAS Allow this section to guide a meditative exploration of your inner world. Visualize, physically touch, and become curious about how your body feels. Studying these 30 asanas can be an engaging way to memorize the muscles and better understand the basics of anatomy, physiology, and kinesiology. I hope these poses, or any variation of them, help you to become more connected to yourself. US_042-043_Opener_AsanaSection.indd 43 21/09/2018 11:09 US_044-045_Opener_SeatedAsanas.indd 44 21/09/2018 11:09 SEATED ASANAS Seated and kneeling poses can be grounding and meditative, often forming the starting and ending points of yoga sessions. The asanas presented here show how the body can benefit physically from yoga in a range of ways. Use variations and modify to find stability and ease in body and mind, and remember: if you can breathe, you can do yoga. US_044-045_Opener_SeatedAsanas.indd 45 21/09/2018 11:09 46 THE ASANAS Seated This seated pose is so called because the traditional purpose of all the other poses is to prepare your body physically for this meditative posture. The neutral spine and engaged abdominals should make this pose steady and comfortable; if it isn’t, try other options. THE BIG PICTURE Your back muscles and abdominals engage, while stretching muscles on the outside of your hips. You may feel this minimally, but for many people it can be challenging to maintain a neutral spine and pelvis, using muscles in ways your body isn’t used to. ACCOMPLISHED Siddhasana Delto idsSh oul der VARIATION The common variation Sukhasana, or “easy pose,” has the legs crossing at the shins. For many, this may not be so “easy;” find support by sitting on a prop to elevate your hips. ALIGNMENT Your spine is neutral, to hold your weight most efficiently. Allow a sense of lightness in your spine. Your shoulders roll back, slightly pulling your shoulder blades together. Spine neutral Pelvis neutral Spine elongating Chin parallel to floor Imagine your head floating up Chest broad Shoulders released back and down Arms Your arms relax with the palms of the hands facing up (supinated). Your posterior deltoid initiates external shoulder rotation, while your anterior deltoid is slightly stretching. Legs crossed comfortably KEY Joints Muscles Engaging Engaging while stretching Stretching US_046-047_Accomplished_01.indd 46 20/09/2018 20:46 47 Thighs and lower legs Your hip flexors – mainly your iliopsoas – help maintain hip flexion. You may feel engagement of more thigh muscles here; consider using props until you can relax unnecessary engagement. Your quadriceps, gluteus maximus, and hip adductors are stretched. You may feel stretching around your ankles, which are in plantar flexion. Rhomboids Iliac us Psoa s ma jor Pec tin eus Hip Glu teu s m axi mu s Ad du cto r lo ng us Ad du cto r m ag nu s Va stu s m ed ia lis Va stu s l ate ra lis Re ctu s f em or isKn ee Spine Pectoralis minor Spinal extensors Latissimus d orsi Rectus abdomi nis Tran svers us ab domi nis Splenius muscles Trapezius Torso Your spinal extensors and transversus abdominis engage to lengthen and stabilize your spine in a neutral position, while your rectus abdominis stretches slightly. Your multifidus engages, sending feedback to your brain about your body’s position. Your rhomboids and middle and lower trapezius engage slightly to retract your scapulae, while you consciously release any tension held in your upper trapezius. Your latissimus dorsi and other back muscles may be minimally engaged to stabilize you in position. Neck To stabilize your cervical spine in a natural curve, your cervical extensor muscles— your splenius capitis and cervicis—engage while in a neutral or slightly lengthening position. Activate this by imagining your head is as light as a helium balloon.Legs crossed comfortably US_046-047_Accomplished_01.indd 47 20/09/2018 20:46 48 Ribcage movement As you inhale, your breastbone lifts while your ribcage expands in all directions and the diaphragm descends. As you exhale, your breastbone and ribs return down and inward; the diaphragm ascends to push out carbon dioxide. Allow this movement as you breathe. ACCOMPLISHED Siddhasana CLOSER LOOK In Accomplished pose, your intervertebral disks are stacked on top of each other, creating the natural curves of the neutral spine. As you breathe, your ribcage expands and releases efficiently, which is facilitated by sitting tall with good posture. Disk stacking When your spine is in its natural curvature—in a “neutral” position (see p.14)—your vertebrae are stacked and the gravitational load on your intervertebral disks is evenly distributed. Your disks are made of squishy fibrocartilage, allowing your spine to move dynamically. Cervical extensor muscles work to lengthen spine Ribcage expands Ribcage contracts Breastbone lifts up and outward Diaphragm contracts and descends Diaphragm relaxes and ascends Breastbone moves down and inward LATERAL VIEW INHALE EXHALE Vertebrae stack vertically Intervertebral disk Hip joint is rotated outward US_048-049_Accomplished_02.indd 48 20/09/2018 20:46 49 Locked long rhomboids If you slouch, your back muscles, including your rhomboids, may be “locked long.” When this happens, your shoulder blades spread forward and your pectoralis minor muscles shorten. Try rolling your shoulders back to awaken your rhomboids. This creates a muscular sling of tension for efficient posture. THE ASANAS Seated Quadriceps stretch Head is light, as if floating upward Enlongating your spine “Axial extension” involves muscle engagement to elongate the axial skeleton (your spine, ribcage, and skull). In many poses, this action counteracts gravity and the tendency to slouch. However, don’t lengthen so much that you lose the natural spinal curves. Like a stretched spring, these curves create support and resilience. Pectoralis minor is short Trapezius is long Rhomboids are long Gravity Neutral spine Spinal extensors Spine Axial extension POSTERIOR VIEW Gluteus maximus stretches and relaxes Middle and lower trapezius engage with rhomboids to stabilize scapulae US_048-049_Accomplished_02.indd 49 20/09/2018 20:46 50 THE ASANAS Seated Bound angle pose is a seated hip opener and groin stretch. It can relieve pelvic cramping, and this version of the pose also improves your ankle flexibility and awareness, which will come in handy in balancing poses. THE BIG PICTURE Your inner thighs stretch, particularly around your groin. If you can reach, this is also an opportunity to stretch your ankle muscles by opening your feet like a book revealing its pages. BOUND ANGLE Baddha Konasana ALIGNMENT Your spine is stabilized into neutral and, in this version of the pose, your pelvis is also neutral. Your thighs rest in a rotated outward position. Arms As you reach toward your feet with flexed elbows, your brachialis flexes your elbow with the help of the biceps brachii and brachioradialis. Pelvis neutral Shoulders relaxed back and down Hip rotating outward Spine neutral Feet opened like book Spine elongated Shoulder Biceps brachiiBrachialisElbow Brachioradialis AnkleExtensor digitorum longus Fibularis m uscles T ibialis anterior Lower legs Your tibialis anterior muscles dorsiflex your ankles, and your extensor digitorum muscles extend your toes. If you are using your hands to manually invert your feet, your fibularis muscles are stretching. KEY Joints Muscles Engaging Engaging while stretching Stretching US_050-051_Bound_angle_01.indd 50 20/09/2018 20:46 51 Torso For many people, there is a tendency to lose natural lumbar lordosis (curve inward) in this pose. To resist this, engage your spinal extensors to lengthen and stabilize your spine. Your rectus abdominis stretches slightly. Thighs Your hip flexors—particularly your iliopsoas—engage to maintain hip flexion. Your quadriceps, along with your adductors, strongly stretch. Although your hamstrings initially engage to flex your knee, in this version of the pose try to relax them as much as possible. This is not a major hamstring strengthener. Brachialis Psoa s ma jor Ilia cus Pec tin eus Hi p Ad du cto r l on gu s Ad du cto r m ag nu s Va stu s m ed ia lis Sa rto riu s Re ctu s f em ori s K ne e Spine Spina l exte nsors Rec tus abd omi nis US_050-051_Bound_angle_01.indd 51 28/09/2018 15:42 52 BOUND ANGLE Baddha Konasana CLOSER LOOK Your one-of-a-kind bone shapes and joint structures determine what your bound angle pose looks like. Some people will never be able to bring their knees to the floor and that is okay. Focus on releasing your hips. Erector spinae engage to maintain posture Multifidus sends sensory information to your brain, helping body awareness Head is stacked over your spine Lower back is curved inward to neutral, not rounding forward Femur differences When seated in Bound Angle pose, notice if you feel a “hard” or a “soft” stop. A hard stop is when the bones get in the way, with little stretching sensation felt. A soft stop is when tight muscles limit movement and a stretching is sensation felt. Soft stops can shift from stretching, but you cannot change hard stops. Variance in femur shape and angle can limit certain poses. Knee is lowered toward floor Head of femur rotates outward in your hip socket Deep angle Shallow angle 140o 130o 115o Normal angle between head and shaft of femur POSTERIOR–LATERAL VIEW US_052-053_Bound_angle_02.indd 52 20/09/2018 20:46 53 THE ASANAS Seated Pubic symphysis made of fibrocartilage Iliofemoral ligament Sacroiliac (SI) ligament Upper arms engage to grasp feet Engage thighs for a few breaths, then allow quadriceps to stretch further Pelvis differences The shape of the pelvis differs in everyone. A key difference is between males and females— women tend to have a wider pelvis to allow for childbirth. Variance in pelvis shape contributes to the fact that everyone has their unique expression of asanas. In Bound Angle your pelvic structure is a factor in how far you can lower your knees. Pelvis softening Women release a hormone called relaxin during pregnancy. Some research suggests women release small amounts monthly around ovulation. Relaxin prepares the body for childbirth, prompting the ligaments and fibrocartilage that support the pelvis to relax and allow for more flexibility. Women should take care to not overstretch during these times. Sacrospinous ligament Angle is greater than 90° Angle is less than or equal to 90° Acetabulum (socket) Thicker bone in male pelvis 90o 130o FEMALE MALE ANTERIOR–LATERAL VIEW US_052-053_Bound_angle_02.indd 53 20/09/2018 20:46 54 THE ASANAS Seated This is a gentle kneeling pose that takes the position of a scared cat, warming up joints in your spine, hips, and shoulders. Try exhaling as you move into the pose. This is often done with the next pose, Cow, by flowing from Cat to Cow with the exhale and inhale. THE BIG PICTURE Your back muscles stretch while the muscles on the front of your body—including your chest and abdominal muscles— engage. Muscles in your arms work to stabilize you. Your rib cage is compressed, helping to facilitate a deep exhale into the pose. CAT Marjaryasana Even curve in spine Fingers spread and palms pressing down Knees hip- distance apart Hands shoulder- distance apart Shoulder blades are wide apart ALIGNMENT Your arms and thighs are fixed in place, with your knees directly under your hips and hands under your shoulders (or slightly forward). The rounding of your spine is as even as possible. Lower torso Your lumbar spine is in flexion, stretching your quadratus lumborum. Your abdominals engage to compress your abdomen, squeezing your belly button in toward your spine. Your pelvis is in a posterior pelvic tilt. Internal obliques Rectus abdominis Iliopsoas H ip US_054-055_Cat_01.indd 54 02/11/2018 14:02 55 Neck Your cervical flexors— sternocleidomastoid, longus colli, and longus capitis— engage. Your cervical extensors—upper trapezius, splenius capitis, and splenius cervicis—stretch as you flex your cervical spine, tucking your chin in toward your sternum. Upper arms Your triceps brachii extend your elbows, while your biceps brachii stabilize synergistically in a lengthened position. Lower arms Your wrist extensors extend your wrists, and your wrist flexors slightly stretch while stabilizing your hands in position. Upper torso The muscles on the front of your body engage to flex your spine— including your abdominals and iliopsoas, while the muscles on the back of your body stretch— including your spinal extensors, trapezius, rhomboids, and latissimus dorsi. Your scapulae are elevated, protracted, and upwardly rotated. Your pectoralis major is slightly engaged. Lower legs Your lower legs are relaxed. You may feel your ankle dorsiflexors stretching if they are particularly tight. Tric eps brac hiiP ec to ra lis m aj or Sh ou lde r Elbow Pa lm ari s lo ng us Wr ist Extensor carpi radialis longusExtensor carpi radialis brevis Flexor c arpi ul naris Extensor carpi ulna ris Flexo r dig itoru m su perfi ciali s Splenius muscles Serr atu s an teri or Erecto r spina e Tr ap ezi us Sp in e Longus m uscles Sterno cleidom astoid KEY Joints Muscles Engaging Engaging while stretching Stretching US_054-055_Cat_01.indd 55 20/09/2018 20:46 56 THE ASANAS Seated Mimicking the slightly dipped back of a cow, this gentle kneeling pose incorporates a backbend, and is practiced to warm up the spine, hips, and shoulders. Inhale as you enter the pose; you can also alternate between this and Cat pose, in time with your breath. THE BIG PICTURE Your abdominal and chest muscles stretch, while your back muscles—including your spinal extensors—engage. Your rib cage is expanding, making it possible to inhale fully. A subtle, even curve is created by the backbend and raised head. COW Bitilasana Even curve in spine Fingers spread and palms pressing down Knees hip- distance apart Hands shoulder- distance apart Shoulder blades squeeze toward center ALIGNMENT Your arms and thighs are fixed in place with your knees under your hips and hands under your shoulders (or slightly forward). Your backbend is as even as possible, focusing on lengthening your neck, creating a subtle, even curve. Especially even curve in neck Rectus abdom inis External obliques Quadratus lumborum G luteus m axim us Rhomboids Spinal extensors Serratus anterior H ips Spine US_056-057_Cow_01.indd 56 20/09/2018 20:46 57 Lower arms Your wrist extensors extend your wrists while your wrist flexors slightly stretch while stabilizing. Neck Your cervical spinal extensors engage, while your cervical flexors stretch slightly as you gently lift your chin. Imagine there is an egg behind your neck—avoid cracking it by resisting hyperextension (extreme extension). Upper arms Your triceps brachii extend your elbows, while your biceps brachii stabilize in a lengthened position. Torso Your spinal extensors engage to extend your spine, while your abdominals stretch. Your middle and lower trapezius retract your scapulae, while your serratus anterior muscles stabilize. Pal ma ris lon gus Wri st Extensor carpi radialis longus Extensor carpi radialis brevis Flexor ca rpi ulnar is Extensor carpi ulnaris Flexor digito rum s uperfi cialis Triceps brachii Pectoralis major Shoulder Elbo w Splenius muscles Longus muscles Sternocleidomastoid KEY Joints Muscles Engaging Engaging while stretching Stretching US_056-057_Cow_01.indd 57 20/09/2018 20:46 58 CAT—COW Marjaryasana—Bitilasana CLOSER LOOK Flowing from the flexion of Cat to the extension of Cow as you breathe deeply in and out improves your mind–body connection, as well as your sense of body awareness. Mind–body connection We often think of the brain as controlling our muscles. This is true: those motor signals tell your muscles what to do. However, your nervous system is a two-way conversation. Your body sends tons of sensory signals to your brain. Yoga improves the mind–body connection by encouraging you to listen to your body. Middle finger is facing forward Ankles and feet are relaxed (in plantar flexion) Spine flexion and extension When your spine flexes, the front of your body engages while the back of your body stretches. When your spine extends, going into a backbend, the back of your body engages while the front of your body stretches. Your spinal extensors are the main players in this extension. ANTERIOR–LATERAL VIEW OF CAT Trapezius stretches Extension Flexion Signals sent from muscles Spinal cord Brain receives signals US_058-059_Cat_Cow_02.indd 58 20/09/2018 20:46 59 THE ASANAS Seated Sensory cortex receives signals from body Inhale, making space for air to come into your lungs Conscious pathway Signals from body to brain Inhalation and exhalation Breathe mindfully, coordinating your breath and movement; your nervous system loves this sort of integration. As a general rule, exhale when your ribcage is compressed (as in forward folds or twists), and inhale when your ribcage can expand (as in backbends). Proprioception Proprioception is body awareness, particularly while moving through space. Your cerebellum constantly receives unconscious signals from your body about its position, while your cerebral cortex consciously deciphers where you are in space. Mindfully flowing between poses can help develop this awareness and improve balance. Pectoral muscles stabilize your shoulders Kneecap may need padding, such as a folded blanket Wrists are extended Cerebellum receives signals Exhale, compressing your ribcage to push air out EXHALE DURING CAT INHALE DURING COW ANTERIOR–LATERAL VIEW OF COW Eyes open or closed Lungs US_058-059_Cat_Cow_02.indd 59 20/09/2018 20:46 60 THE ASANAS Seated This seated pose involves unique actions of your shoulder joints. This can be helpful in stretching out tight shoulders, particularly if you work at a desk and spend a lot of time typing—but you should avoid this pose if you have a rotator cuff injury. Switch arms and notice if you feel a difference between each side. COW FACE Gomukhasana THE BIG PICTURE In this seated pose, you particularly stretch around your shoulders and the outside of your hips and buttocks. You are also engaging key postural muscles to counteract slouching or rounding forward. VARIATION If you cannot reach your hands together, use a strap or towel to extend your reach. If you hold for approximately 10 breaths, you may find you can walk your fingers closer toward each other. ALIGNMENT Your knees are stacked in the center while your hands reach toward each other, trying to clasp your fingertips. Your elbows are squeezing in toward the center. Keep your spine neutral or in a slight backbend, trying to twist or lean. Bottom elbow reaching down and in Keep head and neck back Hip rotating outward Top elbow reaching up and in Work toward stacking knees at midline Spine neutral Torso Your spinal extensors and transversus abdominis engage to slightly extend and stabilize your spine, while your rectus abdominis stretches. Your rhomboids engage to retract your scapulae. Top arm Your shoulder flexors— anterior deltoid and pectoralis major—flex your shoulder. Your middle deltoid and supraspinatus stabilize and abduct it, and your infraspinatus, teres minor, and posterior deltoid engage to externally rotate. Your elbow flexors engage and triceps brachii stretches. Reach elbows in as much as possible Grip strap while holding pose KEY Joints Muscles Engaging Engaging while stretching Stretching US_060-061_Cow_face_01.indd 60 20/09/2018 20:46 61 Bottom arm Your anterior deltoid, subscapularis, teres major, pectoralis major, and latissimus dorsi internally rotate your shoulder. Your posterior deltoid stretches while in internal rotation. Your elbow flexors engage while your triceps brachii stretches. Neck Your splenius capitis and splenius cervicis engage to press your head back, perhaps in slight cervical extension to counteract the tendency of the head to fall forward. Thighs Your hip flexors help stabilize your hips in flexion, while your quadriceps and gluteus medius, minimus, and maximus stretch. Latissimus dorsi Cervical e xtensors Gluteus medius Gluteus ma ximus Rhom boids Serratus anterior Spinal exten sors Spine Transversus abdominis Infraspinatus Teres major Teres minor Deltoids Brachialis Triceps brachii Elbow Shoulder Brachiora dialis Biceps brachii Deltoids Brachioradialis Tricep s brac hii Elbo w Brachialis Biceps brachii Teres major Infraspinatus US_060-061_Cow_face_01.indd 61 20/09/2018 20:46 62 COW FACE Gomukhasana CLOSER LOOK Cow Face works your shoulders dynamically—including your deltoid muscles. Compression at your shoulder joint can also lead to cardiovascular shifts both system-wide and in local blood vessels. All of your gluteal muscles stretch, including your gluteus maximus Pectoralis major stretches while flexing your shoulder Triceps brachii stretches strongly on your top arm Fingers gently clasp, if accessible Latissimus dorsi stretches on this side Middle— abduction Dynamic deltoids Your deltoids are split into three parts, or heads, which have opposing actions when engaged. Some research suggests that there are 19 parts filled with muscle fibers that can be controlled independently by your nervous system. This pose dynamically engages and stretches each part of your deltoids. Anterior—flexion and internal rotation Posterior— extension and external rotation LATERAL VIEW US_062-063_Cow_face_02.indd 62 20/09/2018 20:46 63 THE ASANAS Seated Blood vessel changes There is slight pressure on your blood vessels at your shoulders, similar to a loose tourniquet. When you release the pose, blood rushes to the area. This vascular pressure causes an increase of nitric oxide (NO), encouraging blood vessel dilation, slightly lowering blood pressure and increasing relaxation. Range of movement Your body has the potential to do many actions, but our modern-day lifestyle limits its opportunities. Humans are designed to go through more joint actions more regularly. Your yoga practice helps you maintain these capabilities in full range of motion (ROM). When it comes to ROM, if you don’t use it, you lose it. Collarbones move slightly with your arms Extension Flexion Internal rotation External rotation Eyes open or closed Middle deltoid stretches as you slightly squeeze your elbow inward Pectoralis major engages to strongly adduct your shoulder Psoas major on both sides engage to flex your hips Ankles and feet are relaxed Vasoconstriction (vessel constricting) Vasodilation (vessel opening) ANTERIOR VIEW US_062-063_Cow_face_02.indd 63 20/09/2018 20:46 64 THE ASANAS Seated This seated, lateral side stretch allows you to mobilize your spine in a way that you probably don’t often move it in everyday life. The novel movement that this pose involves benefits your intervertebral discs, nervous system, and fascia. THE BIG PICTURE As you bend deeply to the side, muscles along your spine stretch and strengthen. Your shoulder muscles engage to reach your arms over your head, and your thigh muscles on both sides stretch in different ways. SIDE BEND Parivrtta Janu Sirsasana Neck To rotate your neck, your rotatores, multifidus, sternocleidomastoid, and semispinalis cervicis engage on the side toward the ground (model’s right in this image), while stretching on the upward-facing side. Your splenius capitis and splenius cervicis engage on the upward-facing side (model’s left in this image), while stretching on the downward-facing side. Arms Your shoulder flexors—including the anterior deltoids—engage. Your middle deltoids and supraspinatus engage to abduct your shoulders, and they are externally rotated by your posterior deltoids, infraspinatus, and teres minor muscles. Your brachialis, biceps, and brachioradialis muscles flex your elbows. Thigh Your hamstrings and gluteus maximus stretch, while your quadriceps engage to extend your knee. Also, your internal rotators— including gluteus medius, gluteus minimus, and tensor fasciae latae— engage while lengthening. You may feel a stretch in your iliotibial band. Extended lower leg Your ankle dorsiflexors engage to dorsiflex your ankle and extend your toes. If you are grabbing your foot and pulling, you are probably feeling a stretch in your calf muscles, along with your plantar muscles and fascia. KEY Joints Muscles Engaging Engaging while stretching Stretching Deltoids Serratus anterior Triceps brachiiBrachialis Biceps brachii Brachioradialis T ibialis anterior Flexor d. longus G astrocnem ius Plantar fascia Sternocleidom astoid Shoulder Elbow Ankle US_064-065_Seated_side_bend_01.indd 64 20/09/2018 20:46 65 ALIGNMENT Avoid rounding forward by reaching your top shoulder blade back, as if you are trying to press toward an imaginary wall. Focus on finding length in your spine and broadness in your chest. Spine elongating Turn head comfortably Knees soft, not locked Chest broad Bring shoulder blade back Flexed leg Your adductors, quadriceps, and iliopsoas stretch. Although your hamstrings engage initially to flex your knee in place, try to relax your leg muscles while holding the pose. Torso On the side toward the ground your external abdominal obliques, erector spinae, and quadratus lumborum engage while the upper side stretches, to laterally flex your spine. On both sides, your rotatores and multifidus rotate your spine and send signals to your brain about where your spine is in space. Your transversus abdominis engages to stabilize your spine. S pi na l e xt en so rs Ex te rn al o bl iq ue s Va stu s m ed ia lis Sa rto riu s Ad du cto r m ag nu s Ps oa s m ajo r R ec tu s f em or is Va st us la te ra lis K ne eGl ute us m ax im us Pe cti ne us R ectus fem oris Semitendinosus A dductor m agnus Iliopsoas Sp in e US_064-065_Seated_side_bend_01.indd 65 20/09/2018 20:46 66 SIDE BEND Parivrtta Janu Sirsasana Disk pushes to opposite side of bend Vertebra Disk health When side-bending (lateral flexion of the spine), your intervertebral disks push to the sides. As you bend to the right, your disks shift to the left (and vice versa). The cartilage in your spine allows for this natural process. Unilateral movement Your quadratus lumborum (QL) is important for holding posture. When the erector spinae are weak it picks up the slack. Keeping your spine erect is a big job for this little muscle, leading to muscle fatigue and even pain. This pose helps by stretching and engaging the QL. CLOSER LOOK Seated side bend is a one-sided movement that dynamically affects your abdominals, back muscles, and spinal disks. You don’t have to be able to reach your foot with either hand to do this pose; your arms can simply reach to the side. Abdominal structure Your criss-crossing abdominal muscles provide multilayered support for your internal organs and allow your torso to move. Legend has it that in 1888, Dr. Dunlop, a surgeon, was watching his son bouncing on his tricycle due to the poor design of the wheels, causing a headache. Inspired by the structure of the abdominals, he designed a tire for a smoother ride and fewer flats. Quadratus lumborum engages on lower side Quadratus lumborum stretches on upper side External oblique Transversus abdominis Internal oblique Rectus abdominis Latissimus dorsi stretches on the upper side US_066-067_Seated_side_bend_02.indd 66 02/11/2018 14:02 67 THE ASANAS Seated Pressure and balance Notice and feel the point of contact of your body on the floor in this pose. It is a little different for everybody. Notice how the pressure points shift as you transition in and out of the pose. If hands don’t reach foot, place one hand on your shin and reach the other out and over toward it Erector spinae engage on the lower side Elbow flexors engage POSTERIOR VIEW Posterior deltoid stretches and engages to help externally rotate shoulder Ankle dorsiflexors engage to flex your ankle Erector spinae stretch on the upper side Knee may be lifted or touching the floor Weight is back on buttocks US_066-067_Seated_side_bend_02.indd 67 02/11/2018 14:02 68 ALIGNMENT Prioritize elongating your spine over rotating more or leaning. If you do decide to rotate more deeply, try to use your core muscles instead of pulling with the external force of your arms. Arm presses down Spine elongating Keep the rotation as even as possible Pelvis rotates slightly with you THE ASANAS Seated This seated twist will wake up small muscles along your spine and stimulate digestion. Practicing twists mindfully in yoga can help prevent injury from twists you do in everyday life. Take care not to twist too far if you have spinal disk issues or osteoporosis. THE BIG PICTURE Your back muscles and abdominals dynamically engage and stretch as you rotate your spine. Your thighs and hips— particularly around your buttocks—are stretching as they rotate outward. Your lowered arm presses down to help you find more length along your spine. SEATED TWIST Ardha Matsyendrasana Neck To rotate your neck, on the contralateral side of axial rotation (side you are rotating away from, model’s left side on this image), your rotatores, multifidus, sternocleidomastoid, and semispinalis cervicis engage while stretching on the ipsilateral side (the side you are rotating toward). Your splenius capitis and splenius cervicis engage on the ipsilateral side, and stretch on the contralateral. Arms On your extended arm, your teres minor engages to stabilize and externally rotate your shoulder, while your teres major extends your shoulder. Your elbow flexors and triceps are dynamically engaging to help hold your arm in place, pushing down into the ground to help elongate your spine. On your flexed arm, your elbow flexors engage while your triceps stretches slightly. Sternocleidoma stoid Biceps brachii Brachioradialis Elbow Shoulder Teres major Teres minor Triceps brachii Brachialis KEY Joints Muscles Engaging Engaging while stretching Stretching US_068-069_Seated_twist_01.indd 68 20/09/2018 20:46 69 Torso On the contralateral side of axial rotation (this model’s left), your external abdominal obliques engage, while your internal abdominal obliques stretch. On the ipsilateral side, your internal abdominal obliques engage while your external obliques stretch. Your spinal extensors engage on both sides—including your erector spinae and quadratus lumborum muscles. Thighs In your top thigh, your gluteus maximus, tensor fasciae latae, iliotibial band, and quadriceps stretch. In your bottom thigh, you may feel most of the stretch in your quadriceps. Knee HipGluteu s maxim usGlute us medius Iliop soas Vastus lateralis Rectus femoris Vas tus me dia lis Iliotibial band Sart oriu s Spine Qu ad rat us lu mb oru m Ex ter na l ob liq ues Ere ctor spi nae Tra nsv erso spin alis Serra tus a nteri or US_068-069_Seated_twist_01.indd 69 20/09/2018 20:46 70 SEATED TWIST Ardha Matsyendrasana CLOSER LOOK Spinal twists affect the disks between your vertebrae and your sacroiliac joint. Although this action may not “wring out toxins” as is sometimes claimed, it does encourage healthy digestive movement in your intestines, known as peristalsis. Spinal rotation With rotation of your spine (spinal twists), your intervertebral disks naturally compress. For optimal safety and benefit, first consciously lengthen your spine into axial extension as much as possible, then twist only as far as your muscles bring you. Use your arms to help you maintain length in your spine. Breathe. Small, deep muscles called rotatores help to rotate your spine Intervertebral disks compress Vertebrae rotate Gluteal muscles stretch Foot is relaxed External obliques engage as you twist away US_070-071_Seated_twist_02.indd 70 25/09/2018 17:03 71 THE ASANAS Seated Sacroiliac joint Allow your sitting bones to move slightly on the floor with the twist. If you anchor them down, the twist puts a lot of pressure on the structure of the SI joint, which can cause aches. Alternatively, allowing too much movement in your SI joint can also lead to achiness. Find the middle way for your body. Contracted muscle Relaxed muscle Stimulating peristalsis In your digestive tract, peristalsis is the involuntary engagement of smooth muscles to move digesting food (see p.39). Thankfully, you don’t have to consciously tell your stomach to empty into the small intestines. Stress and a sedentary lifestyle can affect peristalsis and lead to digestive issues. Twisting can stimulate healthy peristalsis. Wringing out toxins You may have heard that spinal twists “wring out toxins.” However, your liver efficiently deals with toxins automatically. Although mechanically compressing the organs may be beneficial, evidence does not show that this contributes to “detoxification.” You can instead visualize wringing out negative energy as you twist, for psychological benefit. Your liver naturally detoxifies Rotation of torso VARIATION For a gentler twist, keep one leg extended and consider not crossing the lifted leg over the midline. Use your arm wrapped around the leg to help you sit tall as you twist. Ilium Sacroiliac joint (SI) Ischial tuberosities (sitting bones) Food moving through the digestive tract POSTERIOR–LATERAL VIEW Leg not crossed over Knee extended Sacrum Deep to the erector spinae, the multifidus is dynamically engaging US_070-071_Seated_twist_02.indd 71 25/09/2018 17:03 72 THE ASANAS Seated Reminiscent of the fetal position and with your weight supported by the floor, the restorative forward bend of Child’s pose can be a deeply relaxing, restful posture for many. It provides a deep but gentle stretch for your back muscles, calming both body and mind. THE BIG PICTURE With as little muscle engagement as possible, your body releases down. In particular your back muscles, buttocks, and ankles stretch out. As you breathe de