Practical Ways to Protect the Disks
How can you protect your students from disk injuries or avoid exacerbating existing injuries? The specific asana suggestions that follow are intended only for healthy students. See the next section for advice on dealing with students who have disk injuries.
Never force the spine into a forward bend. This is the most important precaution a yoga teacher must observe to prevent disk injuries. It is especially important never to push on a studentís back to bend it forward, particularly if her legs are straight (straight legs stretch the hamstrings, holding the pelvis fixed, and thereby focus the bend on the lower spine). If for some reason you must perform a hands-on adjustment, place your hands on the posterior-superior part of the ilium bones (on the upper, back side of the pelvis, alongside the top of the sacrum) and guide (don't push!) the student forward in a way that rotates the pelvis around the heads of the femurs. Also, teach students not to force their own spines into flexion by pulling strongly with their arms, contracting their abdominal muscles, bouncing, etc.
Loosen the hamstrings and hip rotator muscles. Stretching the hamstrings and hip rotators reduces risk of disk injury by freeing the pelvis to move independently of the legs. This allows the hip joints to flex more and the spine to flex less when bending forward or sitting upright. Maintaining a regular yoga practice is a great way to free the pelvis, and this is one reason it is so good for the back. But herein lies the rub: the very poses that loosen the hamstrings and hip rotators--forward bends--are also potentially the most dangerous for the disks. It all depends on which postures you choose and how you teach them.
Reclining forward bends such as Supta Padangusthasana (Reclining Big Toe Pose) are easiest on the disks. They provide the safest way for tight students to stretch the hamstrings and hips. Standing forward bends, such as Uttanasana (Standing Forward Bend), although harder on the disks, provide the best trade-off between safety on the one hand and stretch, strengthening, precise alignment, and body awareness on the other. They are suitable for most healthy students, but may need to be modified for tight students. Seated forward bends, such as Paschimottanasana (Seated Forward Bend) are good for improving sitting posture and for stretching deeply, but they are hardest on the disks and so must be practiced with the greatest caution. They usually require modification for all but the most flexible students.
To make forward bends safer, the teacher must be careful to focus the action in the hip joints, not in the lower back. One good rule of thumb is the 90-degree rule: Do not start bending the spine forward until the pelvis appears to be at a 90-degree angle to the legs. If the student cannot achieve 90 degrees, ask him not to bend the spine forward at all, but only to work on the pelvic tilt. Support him with props if necessary to achieve this. For example, he could rest his hands on a block in Uttanasana, and elevate his pelvis on a stack of folded blankets in Dandasana (Staff Pose). Once the pelvis tilts past 90 degrees in relation to the legs, ask him to flex his spine only moderately.
How much flexion is OK? Hereís another convenient rule: Find a photograph of a skilled yoga practitioner with very loose hamstrings practicing Uttanasana (Standing Forward Bend) such as this one. The practitioner should be folding fully forward at the hips, elongating the front of her body, and resting the ribs and forehead on her legs. Look carefully at the degree of rounding of her back. A healthy yoga student whose hamstrings are not as loose as those of the photo model should tilt the pelvis forward until it stops, then, keeping the front of the body as long as possible, round her back only as much as the model does in full Uttanasana.
Lengthen the spine. Actions that put traction on the spine pull the vertebrae apart, increasing space for the nerves and helping the disks soak up fluid. There are simple ways your students can learn to apply traction to their own spines in asanas. One is to press their hands down into the floor while sitting in Dandasana. The downward pressure of the hands lifts the spine away from the pelvis. This action can precede many different seated forward bends or twists. There are also numerous ways to apply traction with wall ropes. One is to sit facing the wall and grasp high wall ropes to pull the trunk diagonally up and forward in partial Paschimottanasana.
Sit well. When we stand, the lumbar spine normally curves inward in what appears to be a slight backbend (lordosis). This is the healthy neutral position for the disks and spinal nerves. Teach your student to maintain this curve (but not increase it) while sitting upright in poses like Baddha Konasana (Bound Angle pose) or Sukhasana (Easy Pose), and in twisting in poses like Bharadvajasana (Bharadvajaís Twist). If his lumbar spine flattens or flexes, elevate his pelvis on enough folded blankets or other props to re-establish the curve. Also, advise your students to maintain the normal curve of the spine while sitting in daily life, and encourage them to take frequent breaks if they must sit for long periods. A good way to take a break is to stand and walk for a while, but the best way is probably to lie down. Reclining gentle backbends may be particularly good for many people. Most non-seated asanas are also helpful. Even seated poses, though not ideal, provide relief from prolonged chair sitting.
Strengthen and stretch trunk muscles. Strong erector spinae muscles are essential to maintaining the lumbar curve, especially while sitting, but if they are too tight, they can compress the disks. Standing poses are ideal for stretching these muscles because they also strengthen them in the stretched position. One of the best actions for achieving this kind of strength is to elongate the front of the body while coming up out of Uttanasana.
Physical therapists recommend strengthening the abdominal muscles to keep the back healthy. They often recommend partial sit-ups with the knees bent, because full sit-ups, or sit-ups combined with straight-leg lifts, as in the yoga pose Paripurna Navasana (Full Boat pose), can be hard on the back. Also, if the abdominals get too tight they can cause excessive flexion in the lumbar and disk compression. Therefore, any abdominal strengthening program should be counterbalanced with a backbending routine to stretch these muscles.
Maintain a well-rounded practice. Disks do not live by forward bends alone. They also need backbends, side bends, and twists. A well-rounded yoga practice is best for preventing disk injuries.
Dealing with Existing Disk Injuries
To teach yoga to a student who already has a disk problem, you need specialized knowledge that is beyond the scope of this article. However, here are a few general suggestions:
Practicing yoga is great for your disks if you do it right, but potentially harmful if you do it wrong. Itís easy to learn how to protect and nourish the disks in yoga. With a little knowledge, you can help your students avoid injury and keep their backs healthy for a lifetime.
Roger Cole, Ph.D. is an Iyengar-certified yoga teacher (http://rogercoleyoga.com), and Stanford-trained scientist. He specializes in human anatomy and in the physiology of relaxation, sleep, and biological rhythms.