Yoga Basics: How to Keep Your Hamstrings Happy in Forward Bends

Protect your Hamstrings While Doing Yoga!

“Bend your knees!” is a common cue used in yoga classes to protect the back when bending forward. Even though Uttanasana (Standing Forward Fold) is traditionally done with straight legs, many people’s bodies are unable to bend forward from the hips with their knees straight. 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. But attempting to bend forward with straight knees may cause harm. In our effort to bow to the sun, we risk overstretching our hamstrings and compromising our intervertebral discs unless we bend our knees.

What Are Hamstrings Anyway?

The hamstrings muscles consist 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 shin bone (tibia). The biceps femoris originates at the ischial tuberosity 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 risk factors for hamstring injuries such as hamstring weakness or decreased lumbopelvic stability1.  

The effects of gravity should not be discounted while lowering the body towards the floor. Strength is required to lower your body into forward bending poses rather than simply collapsing.  

The normal range of motion of the hamstring group is 80 to 90 degrees with 90 degrees being a right angle to your torso. Visualize the motion required in Parsvottanasana (Intense Side Stretch Pose). One leg is extended forward, while the other one is two to three feet behind it, knees are straight, and both feet are flat on ground. In this stance you then lengthen the spine forward and attempt to lower the hands toward the floor. When you begin to bend forward in this stance, your front leg will flex well past 90 degrees. To get your hands to the floor (or blocks) while still hinging from the pelvis requires not only greater than normal hamstring flexibility, but also lumbar spine flexibility, strength and the ability to control this movement while moving toward the floor.   

In poses whose names have the word “intense” (utthita in Sanskrit) in them, warm-ups and preparatory poses are essential. I recommend incorporating a variation of a hamstring stretch such as Supta Padangustasana (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?

Study with YogaUOnline, Doug Keller’s amazing course:  Yoga for Healthy Hamstrings, Unraveling the Knots.

Another great article and interview with Doug Keller read more on: Hampered by Hamstrings? Tips and Tricks for Healthy Yoga Stretches.

Reprinted with permission from

Christine CarrChristine Carr is the owner of Synergy Physical Therapy and Yoga, Inc. in Evergreen, Colorado.  She incorporates both physical therapy and yoga in her work helping clients ( She has been a physical therapist for 18 years and a yoga therapist for 11 years. Christine has studied with various yoga teachers and styles being drawn most to the Iyengar lineage and therapeutics in general.  She now assists workshops in therapeutics for both the Professional Yoga Therapy Studies and Rachel Krentzman’s Yoga for a Happy Back Program. Her passion for learning and contributing to her field led her to Dr. Matthew Taylor, PT, PhD,   E-RYT 500 for whom she is now contributing articles for his SMARTSAFE yoga blog



  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.

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