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Yoga Anatomy

Flexibility and Yoga 101: What it Means to be Flexible and Why It’s Not Always a Good Thing

New science tells us that our body’s connective tissue, or fascia, determines our baseline flexibility. But practicing yoga can change our muscles’ functional length and our joints’ range of motion. Here's how to use yoga to find a safe level of flexibility and stabilize your joints.

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Despite some of its contortionist asana, yoga isn’t about whether you can get your foot behind your head. Instead, it’s about the process of building awareness and using that awareness to make decisions that help you find health and happiness. . Wisdom is part of the process. But so is biology. Here are three things you should know about flexibility before practicing bendy poses that may, or may not, be right for you.

How Fascia Influences Baseline Flexibility

Your body’s fibroblasts, the worker cells of your fascia— the collagenous web throughout your body— determine the baseline for your flexibility, according to recent research involving fascia. Some people have flexible fascia, while others don’t. That means that Uttanasana (Standing Forward Bend), for example, is more accessible for some people, no yoga practice required.

Fibroblasts also help determine the baseline for how stable your joints are. Flexibility and stability are both important to the health of your tissues and joints. You want them in balance with each other. “Stretch without stability, not so much fun,” says author of Anatomy Trains, co-author of Fascial Release for Structural Balance, and a bodyworker and teacher of bodywork for 45 years. “Stability without stretch, not so much fun.”But first, take a minute to figure out how loose or tight your own fascia is around your muscles, ligaments, tendons, and joints.

How to Measure Flexibility

Ask someone if they are flexible, and they probably will reach for their toes. But there’s a more accurate way to gauge baseline flexibility: Beighton tests. To perform one of the key measures, hold one arm ahead, bend your elbow, and then drop your hand toward your forearm, palm down. Now gently use your other hand to draw your test arm’s thumb toward the corresponding forearm.

The closer your thumb gets to the forearm, the more intrinsically flexible you are, tending toward a “temple dancer” body type. The farther your thumb is from your forearm, the less intrinsically flexible you are, tending toward a “viking” body type, according to Myers.

“It seems to be a genetic thing,” says Myers. “There’s lots we don’t know about this yet because the research is new.” Generally, “we all live on a spectrum” between the two types, he says.


Temple Dancer Body Type

A temple dancer has looser fascia that builds more slowly. The fascial net tends to be less capable of keeping joints stable. This body has fewer fibroblasts. “People who are very bendy are going to have to rely on their muscles for stability,” Myers says. It’s better for people with this body type to do minimal passive stretching. For example you want to avoid lingering in postures such as Upavista Konasana (Wide-Angle Seated Forward Bend)..

Instead, practicing strength-building poses, such as Plank, will increase stability in order to counteract too much flexibility. “The muscles will take over the job that the ligaments simply can’t do because they are too elastic, too loose,” Myers says.

Viking Body Type

A viking has denser fascia that builds more quickly. The connective tissue is stiffer, which makes the body more stable, but less permissive of movement. This body type has more fibroblasts. Vikings tend to be more rigid in postures such as Wide-Angle Seated Forward Bend, perhaps struggling just to sit upright with their legs barely straddled. They have to work toward becoming more flexible, and yoga postures focused on stretching can help.

“The type of fascia you have is not right or wrong,” Myers says. “You just can’t expect the same behavior out of these two body typesf.” Also, both ends of the spectrum can be dangerous: Extreme fascial looseness, for example, is seen in Ehlers-Danlos syndrome, and extreme fascial stiffness can show up as calcification of the spine, such as in ankylosing spondylitis.


Types of Fascia and How They Each Affect Flexibility

Yoga practice can increase flexibility over time, from the range of motion of joints to functional length in muscles. Some theories say that gains in flexibility come from an increased tolerance for stretching tissues. Others point to increases in the functional length of muscle fibers. It is clear that movement organizes fascia. But “there is no definitive science on stretch,” Myers notes. But there is science on how different types of fascia affect muscle movement and length:

The five types of fascia (myofascia) are within and around your muscles, affecting muscle movement and length, are:

  1. Endomysium Fascia: This is the smallest fascia in muscle. It surrounds each individual muscle cell and fiber. Fascia can be held long or short, meaning it can stretch and contract with your muscles. “Trouble comes when the muscle is held short and stays held short,” Myers says. “The fascia gets stuck in this position.” Yoga postures help release the stickiness, increasing your muscles’ ability to to stretch (acting as antagonists)–or contract (acting as agonists) when you may tend toward loose ligaments and unstable joints.
  2. Perimysium Fascia: This is the fascia that is between different parts of a muscle and between cells and fibers. When hydrated, the perimysium allows different parts of muscles to slide against each other, creating more functional length. Yoga and exercise hydrate the perimysium.
  3. Epimysium Fascia: This is the fascia that surrounds each muscle and separates it from anything near it (fat in the skin, for example) but also is continuous with the endomysium and the perimysium. The epimysium determines the length of each muscle. “That’s the part everyone knows as fascia, the Saran Wrap around the muscle,” Myers says. “It’s really readily visible.”
  4. Intermuscular Fascia and Extramuscular Fascia: This is the fascia between muscles. Intermuscular fascia allows, but also limits, glide between two muscles. Think of intermuscular fascia as the rungs between the two stanchions of a movable ladder, where the stanchions are the muscles. The muscles can move only as far as the rungs let them.
  5. Intermuscular septum: This is the fascia that surrounds groups of muscles. The intermuscular septum separates muscle groups from each other.

Study more with Tom Myers in his online courses with Yoga Journal: Science of Stretch: Anatomy Training for Stability and Resilience with Tom Myers and Anatomy 101 with Tom Myers.