Don’t Let Your Hamstrings Leave You Hamstrung!

Protect them while doing yoga

“Bend your knees!” is a common cue used to protect the back when bending forward.  In yoga, bending the knees in forward folds is also recommended to prevent strain to the back. Uttanasana (standing forward bend) in the traditional version is done with straight legs.   A forward fold (hinging at the hips with the body hanging perpendicular to the ground) can provide traction to the spine and a nice stretch to the hamstrings.  Many people do not have the flexibility to fold forward from the hips, keep the spine straight and keep the knees straight all at the same time.  Attempting to do so may cause harm.  In our effort to bow to the sun, we risk over stretching the hamstrings unless we modify.

What Are Hamstrings Anyway?

The hamstring muscle consists of the semimembranosus, semitendinosus and the biceps femoris.  The former two span from the sit bone (ischial tuberosity which is part of the pelvis) to the inner part of the knee inserting on the chin bone (tibia).  The biceps femoris courses the back of the leg and inserts on the head of the fibula, the outside of knee.   The primary action of the hamstrings is to extend your hip as you flex your knee.   To stretch this muscle, you would do the opposite motion – flex the hip and extend the knee.  This is the precise motion we do in asymmetrical forward folds such as padangustasana (extended hand to toe posture) and parsvottanasana (intense side stretch).  Forward folds such as uttanasana do stretch the hamstrings, but not to the extent that asymmetrical forward folds do.

Risks and Hamstring Ahimsa (non-harming)

Asymmetrical forward bends are more challenging to the hamstring group than symmetrical forward bends. This is due to the pelvis moving slightly (and therefore the attachment site of the hamstrings)  in opposite directions right and left by the force of opposing muscle groups.   These poses include parivrtta trikonasana (revolved triangle), parsvottanasana (intense side stretch) and variations of these poses. These poses are challenging if you have hamstring weakness or decreased lumbopelvic stability which are risk factors for hamstring injury1.  The effects of gravity should not be discounted while lowering the body towards the floor.  Strength is  required to ‘lower’ in poses rather than collapse.

The normal length of the hamstring group is 80 to 90 degrees with 90 degrees being a right angle if you were lying down and lifting one leg towards the sky.  If you visualize the motion required in the intense leg stretch pose (legs staggered one forward and one back, knees are straight, feet flat on ground.  In this stance you then lengthen the spine forward and attempt to lower the hands toward the floor), you can imagine the angle or length required in the hamstrings to lower to the floor is more than 90 degrees.  To get your hands to the floor (or blocks) safely requires not only above ‘normal’ hamstring flexibility, but also lumbar spine flexibility, strength and the ability to control this movement while moving towards the floor.

In poses that by definition have the word ‘intense’ in them, warm ups and preparatory poses are essential.  I recommend incorporating a variation of a hamstring stretch such as padangustasana (or simply lying on floor stretching the leg with the knee straight using a strap) as well as other preparatory poses to warm up the body.

Following are recommendations for alignment in parsvottanasana:

  1. Increase the width of the base of support so you can easily balance and square the pelvis forward.
  2. Line the outer edge of front foot parallel to the edge of the mat.  This will help you to grip the front heel inwards slightly which activates the outer hip muscles.  This action will assist in preventing the front hip from rolling inward and assist in pelvic alignment.
  3. Start with your hands on the hips as you lengthen the spine forward to ensure your pelvis stays level.  Go ⅓ to ½ of the way down at first with a straight spine.  If you feel a hamstring stretch already, it is not advisable to proceed keeping the knee straight.
  4. Allow the tailbone to move towards the back heel and the abdomen to move up and forward toward the front heel.  This motion will prevent over stretching the hamstring tendon.
  5. Push the front leg forward and the back leg back.   This action will cause a reflexive response that relaxes the group.  This is further enhanced if you also lift the knee cap or activate the thigh muscles.
  6. The above action # 5 also engages the lumbopelvic stabilizers. Fascial connections of hip flexors and extensors blend into abdominal and back muscles respectively.  This stabilization effect is enhanced by lengthening the spine forward and controlling the downward motion of the trunk over the forward leg.
  7. Press the ball of the front foot down to unlock the knee, activating the gastroc muscle group (calf) and further assist in preventing over stretching.
  8. Finally, proceed with folding forward with a slightly bent knee. Straighten the knee in the final pose if you do not already feel a stretch in the hamstrings.

Our hamstrings and their testiness can be our teachers in learning to slow down and enjoy the process rather than rushing to the perceived goal.   That is practicing SMART SAFE yoga!

How do you keep your hamstrings smart and safe?


  1. Heiser T. Weber Sullivan G, Clar P, Jacobs R: Prophylaxis and management of hamstring muscle injuries in intercollegiate football players. AM J Sports Med 12:368-370, 1984.


  1. Ida himes on September 19, 2015 at 3:27 pm

    Very informative and clearly written.

  2. Len on October 1, 2019 at 8:19 am

    I just had surgery to repair my hamstring from overstretching in forward bends in yoga. I will practice these cues for the rest of my life!! I wish instructors gave these cues, particularly since there is an overemphasis on forward bends in vinyasa.

    • Dr. Matthew J Taylor on October 1, 2019 at 12:58 pm

      sorry you learned via the school of hardknocks Len. Here’s hoping you have a strong recovery and long practice! ~ matt