This is one of the main physical benefits people want from their yoga practice.  Often they specifically mean hamstring flexibility.

Most people have tight hamstrings because they spend so much time sitting.  This is especially true for children who develop the habit of sitting at the tender age of 6 when they enter school.  I am often amazed at how tight some young people can be.  (I taught a goat yoga class this weekend and there were three young boys who came with their mother.  They looked like they were about 11 years old.  Not a single one of them could sit on the ground without their back rounding!)

A lot of people engage in physical activities that may strengthen and shorten their hamstrings such as running or cycling.  If you are interested in flexibility it is important to stretch after these, or any other physical activities.

Tight hamstrings are not just a problem in your yoga practice; they also can have an effect on your everyday life.

The hamstrings are a group of three muscles located on your posterior thigh that connect your sitting bones to the back of your knee.  They are responsible for extending the hip and flexing the knee.  If these muscles are tight, you may feel pain in your lower back, buttocks, legs and knees.  If you have these symptoms it is worthwhile spending some significant time stretching to loosen and lengthen these muscles.

Stretching the hamstrings means moving the sitting bones away from the back of the knee.  Lengthening and loosening your hamstrings could take several weeks or several months, or sometimes even longer.  The exact amount of time depends on your degree of tightness, your diligence in stretching and your technique.

In yoga, there are three main categories of poses that will stretch your hamstrings: standing, seated and lying down.  It isn’t necessary to do all of the stretches, pick one or two stretches that you like to do and try to do them every day.  If possible try to do theses stretches more than once a day, they way you would do your physical therapy exercises.  Stretching once or twice a week isn’t enough to change your flexibility.  You have to be willing to commit to at least three times a week to see a noticeable change.

No matter which stretches you choose to do, there are just a two guidelines to follow.

The first one is to keep your legs straight and your quadriceps engaged.  The hamstrings stretch when the sitting bones move away from the back of the knees. The quadriceps straighten the legs moving the back of the knee away from the sitting bones. If you bend the knees, you are shortening the hamstrings at the knee.  Also, muscles work in reciprocal pairs; tightening one muscle signals the brain to let the other muscle stretch.

The other guideline to keep in mind is to keep your back straight.  If you round your back, you are shortening the hamstrings at the sitting bones.  In addition, forward bending should happen where your thigh bone meets your pelvis – this is your hip joint.  Flexing by rounding your spine puts a lot of pressure on your lumbar vertebrae and discs.  Think about keeping the front of the body long as your fold.

Standing Poses

The main way to stretch your hamstrings is through the straight leg standing poses such as:  Triangle, Revolved Triangle, Standing Wide Leg Forward Fold, Pyramid, Standing Forward Bend, Half Moon and Revolved Half Moon.  These are the basic standing poses.  I like this category of poses best for tight hamstrings because the pull of gravity on your torso helps with the stretch.  You can do these poses almost anytime and anywhere.  When you first start to practice these poses on your own, look at yourself in a mirror.  This was you can see if your back and legs are straight.  There is a stage of every forward bend called concave spine. I cannot emphasize enough how important this stage is.  Getting your hands to the floor with your back rounded can create patterns and problems with your low back.

Seated Poses

If you can easily sit on the floor with your back and pelvis at 90 degrees and your legs stretched straight out in front of you, then the seated poses are good for you.  If you find that it is difficult to sit on the floor this way because your pelvis is falling backward and your back is rounded, then stick with the standing poses until you are more flexible, or you can sit up on a folded blanket that helps you get your spine straight.

The most common seated poses for stretching your hamstrings are Staff Pose, Seated Tree, Seated Wide Legs – stretching forward and sideways towards each leg, and Seated Forward Fold.

Supine Poses

The main supine pose is Hand to Big Toe Pose.  Of course, if you cannot reach your big toe with your hand, use a yoga strap to help you.  You can do this stretch actively or passively. 

To do this stretch passively, lie on your back on the floor next to a wall. With your arms outstretched at your sides, extend one leg up the wall so it forms as close to a 90-degree angle with your body as possible. Make sure your torso is flat on the floor and you have a normal low back curve.  The leg that is on the floor should be straight with the back of the thigh reaching towards the floor and not buckling up toward the ceiling. Hold this position for 15 to 30 seconds and then repeat on the other leg. Perform this stretch three to four times total every day.

To do this pose actively, lie on your back in the middle of the floor.  Raise one leg to 90 degrees and hold it up there with your hand or a yoga strap (or any alternative). Make sure the leg is straight.  Keep your back straight with a normal lumbar curve.  Make sure you are not lifting your shoulder off of the floor to reach the foot.  And keep the inner thigh of the other leg  reaching towards the floor.  Hold this for 30 seconds to 1 minute and then switch legs.  For extra added benefits, do it 3 times on each leg.