Get to Know Your Hamstrings: Why Both Strength & Length Are Essential

Flexible and strong, hamstrings are key to a healthy, happy yoga practice. Here's what you need to know in order to lengthen and strengthen these muscles.
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hamstring anatomy

When I was in my early 20s, I had a vigorous Ashtanga Yoga practice, and I loved that my hypermobile body could easily contort into even the most advanced postures. Yet my drive to feel a deep stretch, particularly in all of the forward folds in the Ashtanga series, caused microtears in my hamstrings, which led to knee and hip pain—plus so much soreness that when I got out of bed each morning, I wasn’t able to straighten my legs for at least an hour.

Like me, many yoga practitioners learn lessons about their hamstrings the hard way. After all, having the ability to achieve all kinds of complex yoga poses due to hypermobile hamstrings is a common, if unspoken, goal. On the flip side, a lack of flexibility is often associated with not being able to practice yoga at all. How many times have you heard someone say, “Yoga isn’t for me; I can’t even touch my toes!”?

In fact, optimal hamstring health lies somewhere between the two ends of this spectrum. If your hamstrings don’t have a lot of motion, gaining flexibility can help keep your knees, hips, and legs healthy. If your hamstrings are hyperlax, controlling their range of motion will also help you stay injury free. It took me two solid years of avoiding forward bends in order to heal my hamstrings and learn the importance of both stretching and strengthening this muscle group. Here’s how you can create strong, pliable hamstrings, wherever your starting point.

See also Anatomy 101: Understand + Prevent Hamstring Injury

Strengthen to lengthen

It seems paradoxical that if your hamstrings are tight, you should strengthen them. However, hamstrings are healthiest when all of their fibers are able to fully lengthen and contract, which is what prevents muscle tears and promotes optimal muscle health. The following exercise is like medicine for both hypermobile and restricted hamstrings. It’s a concentric exercise (read: it shortens the hamstrings). If you dislike this move as much as I do, take it as a sign that you’ve got some hamstring-strengthening work to do.

The Move: Hamstring Slides

Why Touching Your Toes Is Overrated

Remember the toe-touch test in grade school, where your teacher gauged your flexibility based on how far you could reach your fingers toward your feet? This “test” has been used as a measure of musculoskeletal health for decades. However, hamstring limberness without strength shouldn’t be anyone’s goal. Placing too much focus on stretching your hamstrings can shorten your hip flexors, creating a muscle imbalance that can contribute to an anterior (forward) pelvic tilt—and back pain as a result. 

Body of Knowledge: Anatomy of the Hamstrings

Your hamstrings are a collection of four muscle bellies (with only three names) on the posterior (back) thigh. They originate (attach) on the ischial tuberosities (sit bones) and run down the backs of your thighs. There are two hamstrings in each medial thigh (the inner back side) and one in each lateral (outer) thigh. All three attach by long tendons crossing the back of the knee to the lower leg—and they’re all bi-articular, meaning they connect and affect the function of two joints: the hip and knee. Your hamstrings work to flex (bend) your knees, extend (straighten) your hips, and posteriorly tilt your pelvis.

Biceps Femoris 

This two-headed muscle is in the outer portion of your thigh. The long head begins on the ischial tuberosity (bottom of the pelvis), and the short head is nestled against the lower half of your femur. Both converge at a tendon on your outer knee (at your fibula). This muscle externally rotates your hip. It also externally rotates your bent (flexed) knee.

Semimembranosus

This muscle begins as a thick membranous tendon (hence its name) on your ischial tuberosity (sit bone) and attaches just behind your inner knee. It also serves as
a fascial anchor for the largest of your inner thigh muscles: the adductor magnus.
The semimembranosus muscle internally rotates your hip. It also internally rotates your lower leg at the flexed knee.

Semitendinosus

This muscle begins on your ischial tuberosity and tapers into a long tendon that attaches on the innermost portion of the front of your knee. This muscle internally rotates your hip, and when your knee is bent, it internally rotates your lower leg.

See also Not ALL Hips Need Opening: 3 Moves for Hip Stability

3 Poses to Keep Your Hamstrings Healthy

About Our Pros
Writer Jill Miller is the creator of Yoga Tune Up and The Roll Model Method, and author of The Roll Model: A Step-by-Step Guide to Erase Pain, Improve Mobility, and Live Better in Your Body. She has presented case studies at the Fascia Research Congress and the International Association of Yoga Therapists Symposium on Yoga Therapy and Research, and she teaches at yoga conferences worldwide. Learn more at yogatuneup.com. 

Model Colleen Saidman Yee is a yoga instructor with more than 30 years of practicing experience. She is the owner of Yoga Shanti studios in New York City and author of Yoga for Life.