Stretching tight hamstrings can feel like a lot of effort with little reward. Yoga is often suggested as a great practice for stretching tight hamstrings.  The hamstrings are big, strong muscles that function to bend the knee and extend the hip. And because they cross both the knee AND the hip joint, it is necessary to stretch them with both of these joints considered, or risk overstretching one aspect of the muscle and completely neglecting another portion. This will result in the feeling of the hamstrings not really feeling lengthened at all.
The hamstrings are a group of muscles on the back of the thigh. They are comprised of three muscles: the semimembranosus, the semitendinosus and the biceps femoris. All three muscles attach to the ischial tuberosity, commonly known as the SIT bone, which is part of the pelvis. The muscles then continue down the back of the leg and insert below the knee on both the tibia and fibula. The three muscles are all innervated by a branch of the sciatic nerve, which originates in the low back at the levels of L5-S2. The hamstrings are often mistaken as pulled or injured when the true injury is in the low back. No amount of stretching of the hamstrings will fix a low back injury that is referring pain to the hamstrings.
So how do we stretch tight hamstrings effectively during our yoga practice? There are several poses that specifically stretch the hamstrings. First, to assess just how tight the hamstrings are and begin stretching, sit on the floor in staff pose, Dandasana.  
Sit up against a wall with your back fully supported and your knees bent slightly. Keep a small curve (hollow) in the low back as you fully extend (straighten) the knees, and gently pull the toes back toward you. Can you extend the knees while maintaining the curve in the low back?
If the hamstrings are too tight to allow the knees to fully extend, breathe in the position you start to feel the stretch. Inhale and release the tension, then exhale and work to extend the knees. If you can extend the knees, start to hinge at the hips as you fold forward.  
Once a stretch is felt, hold and breathe. With each inhale, let go of the tension a bit, then lengthen as you fold forward once again. Whether you are folding at the hips or not, the stretch should be just slightly uncomfortable, in the middle of the muscle and not painfully intense. You want to stretch, not injure. Play with bending and straightening the knees to modify where you feel the stretch in the muscle. 
Now make your way into standing to work on a wide-angle forward fold, Prasarita Padottanasana.  Have a block or two close by in case you need to bring the floor to you. Place the feet parallel or slightly toed in.  Maintain a slight lumbar curve, and bend forward, keep the spine long and perpendicular to the floor until a gentle stretch is felt in the hamstrings. To intensify the stretch contract the front of the thighs. This will inhibit the hamstrings and allow them to relax further. The hands now come to the floor directly under the shoulders,  or use the blocks to keep the spine long. Inhale and lengthen, exhale and release for 10 to 20 breaths, then slowly return to standing. 
A third pose that provides an intense hamstring stretch is pyramid pose, Parsvottanasana. Start by placing two blocks in the tall position at the front of your mat. From mountain pose, Tadasana, step one foot straight back, about a legs length distance, and hip width apart to provide a steady base. The knees stay strong and straight, but soft, back toes point slightly out. Press down evenly through the feet, and bend forward at the hips. Pause half way into the fold to assess the hips, check that they are level, then release the hands to the blocks as the spine lengthens forward. Inhale and lengthen, exhale and allow the trunk fold until a gentle stretch is felt. If the pull of the stretch is behind the knee or at the buttock, bend the front knee softly to move the stretch into the middle of the muscle, not at the ends. Repeat for 10 to 20 breaths, then slowly return to standing. Repeat on the other side.
Stretching is considered most effective when the body is warm. Consider doing 3 sun salutations before your hamstring focused practice.   Stretching should feel good, with just a little discomfort in the muscle you are trying to stretch. If it is very painful, or if the pain is not located in the muscle you are trying to stretch, other issues may be present that should be addressed.
~ Andrea Trombley PT, DPT, E-RYT
Join Dr. Andrea Trombley on May 11th for a 1.5 hours hamstring workshop using the Yoga Wall, focused on getting to know the hamstrings and how to stretch them. In addition to the poses mentioned here, you will work on counter-poses to keep you safe, quadriceps stretches to address the front of the thigh, and even more poses to help move you toward your personal goals. Sign up today to reserve your spot – space is limited to 12 participants!

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