Ahhh, Uttanasana. A welcome rest between poses during an invigorating vinyasa sequence, or a relaxing break after vigorous standing poses. Hang down, relax, let it all go, we're instructed. But to get a deeply relaxing stretch in your legs, back, and neck in Uttanasana (Standing Forward Bend), you have to release your hamstrings. Sadly, those students with tight hamstrings and most in need of the stretch that Uttanasana offers are the ones most likely to tense up and contract the hamstrings rather than let them go.
Ideally, in Uttanasana you're stretching the hamstrings on the back of your thighs and contracting the quadriceps on the front of your thighs. The three muscles that make up the hamstrings—the biceps femoris, the semitendinosus, and the semimembranosus—originate on your ischial tuberosities, or sitting bones, on the bottom of your pelvis and insert below the knee on your lower leg. Like any other muscles, the hamstrings try to pull their points of origin and insertion closer together when they contract. This action results in the knee flexing (bending), or the hip extending (straightening, or bringing the torso and thighs into one line), or both. When you stretch the hamstrings, you are doing the opposite action—the knee is straight and the hip flexed. To get the best possible stretch in Uttanasana, you should be positioned so that the hamstrings can relax and lengthen into the stretch, not hold on tight or contract to do the work in the pose.
Three Kinds of Contractions
To understand how your hamstrings work in Uttanasana, you'll first need to understand the three types of muscle contractions—isometric, concentric, and eccentric. The biceps brachii muscle, on the front of the upper arm, is a good muscle for illustrating the types of contraction. Imagine that you're holding a five-pound weight in your right hand, with your elbow bent at about 90 degrees. If you just hold the weight there, the muscle is doing an isometric contraction. It's definitely working, but not changing length. If you bend the elbow more and lift the weight a little higher, the muscle gets shorter, which is a concentric contraction. Finally, if you set the weight down, the elbow moves from bent to straight, and the biceps lengthens but still contracts to control the descent of the weight. This is an eccentric contraction.
Now, let's look at the action of the hamstrings in Uttanasana. Start in Uttanasana, with your knees straight and your pelvis tilted forward, so your spine and head flow down toward the floor. As you start to rise up out of the pose, the hamstrings contract and pull down on the sitting bones, the pelvis comes into an upright position, and the torso comes into a vertical line with the legs. With this action, you've moved from hip flexion in the pose to hip extension in a standing position, and the hamstrings performed a concentric, or shortening, contraction. On the other hand, if you are standing upright and tilt the pelvis forward to move into the pose, the hamstrings do an eccentric contraction—they are lengthening but working hard to control the descent of the torso as the sitting bones gradually rotate upward.
However, if you decide to stop halfway down (or halfway up if you're coming out of the pose), with your fingertips several inches from the floor, the hamstrings will be contracting isometrically. If they didn't contract, your pelvis would tip all the way over and you'd fall to the floor. So they hold you in position, neither shortening nor lengthening, but working hard. And therein lies the problem for students with tight hamstrings: When they come into the pose, their fingers don't reach the floor, so the hamstrings contract to hold the pelvis in place. Then, as the teacher exhorts the class to relax and let go into the hamstring stretch, the tight students are led astray by thinking that what they feel—actually a contracting muscle—is relaxation. And this is a bad situation for the tight students who may already have trouble learning to relax.
Practicing Uttanasana with your hands dangling toward the ground isn't a good idea, not only because of inaccurate learning but also because of the huge strain it can put on the muscles and disks of your lower back; and while the hamstrings are contracting instead of stretching, their flexibility won't improve.
However, there is an easy fix for the problem. Simply put a yoga block or a folded blanket (or a chair, if you're really tight) under your hands, so the weight of your body is supported through the arms to the prop and then to the floor. Because the hamstrings no longer need to support your torso, they can relax, lengthen, and let go instead of contracting. You can visualize the hamstrings lengthening from the back of your knee up the length of your thigh to the sitting bones as you relax into the stretch.
While you're fine-tuning your Uttanasana alignment, make sure your hips are over, not behind, your ankles. When your legs lean back, you take the stretch out of the calf muscles (gastrocnemius and soleus). This happens because these muscles perform plantar flexion (that is, they raise your body up on tip-toe so your foot is in line with your leg) as they contract and shorten the calf muscles. When your legs are perpendicular to the floor, your ankles are bent about 90 degrees, which lengthens and stretches the calf muscles.
Work Your Quads
In Uttansana, like most other forward bends, the knees should be straight. If left to their own devices, the hamstrings will avoid a full stretch by keeping the knees bent. To counteract the tendency, you must contract the quadriceps muscles. The "quads" are made up of four muscles—the vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris. One of the actions of the quads is to extend, or straighten, the knee. So, in Uttanasana the quads need to contract with moderate firmness to counteract the tendency of the hamstrings to bend the knee.
There is an easy way to test whether your quads are contracting correctly. Sit on the floor with both legs straight out in front of you. Put your thumb on one side of a kneecap (patella) and your fingers on the other side. If your quads are relaxed, you can wiggle the patella up and down and side to side. When the quads contract, they hold the patella firmly and you won't be able to move it. To check the quads' action in Uttanasana, just feel your patella.
When you contract your quads, the hamstrings will automatically relax. That's because the quads are what's known as "antagonists" to the hamstrings. If a muscle has a job to do, the nervous system will tell its antagonist to relax. For example, when you're lifting that five-pound weight, with your biceps bending your elbow, your nervous system will tell the triceps, which straightens the elbow, to let go. Contracting the triceps would interfere with the work of the biceps. Applying that rule to Uttanasana, when you contract your quads, your nervous system tells the hamstrings to relax and let go.
Ease on Back
To understand the final muscular action in Uttanasana, let's look at the erector spinae, the group of smaller muscles that form a thick bundle running parallel up each side of the spine. When you roll down into Uttanasana, your erector spinae contract eccentrically in order to control the descent of your torso. When you roll back up, the erector spinae contract concentrically to bring you upright. Going into or coming out of Uttanasana, your pelvis rotates in the appropriate direction due to the action of the erector spinae.
If you lower into the pose with a straight spine, the erector spinae contract isometrically to hold the normal spinal curves as long as possible while the hamstrings contract eccentrically to rotate the pelvis forward. Coming back up with a straight back, the erector spinae again contract isometrically to maintain the normal spinal curves as the hamstrings pull down on the sitting bones, rotating the pelvis to bring you back to standing.
You can feel the hamstrings and erector spinae working hard in the transitions into and out of Uttanasana. Both can relax into the final pose if you support the weight of your torso by placing your hands on the floor or a prop. Over time the lengthening of the hamstrings will allow the pelvis to tilt a little more, the spine will curve into soft flexion as the erector spinae release their load, and your head will hang heavy. Your belly will be soft, and it will gradually lengthen down the front of your thighs as you release deeper and deeper into the pose. Remember though, in the midst of all that relaxation, your quads should still be working.
A physical therapist and Iyengar Yoga teacher, Julie Gudmestad runs a physical therapy practice and yoga studio in Portland, Oregon. She cannot respond to requests for personal health advice.