Stuart McGill, a professor and director of the Spine Biomechanics Laboratory at the University of Waterloo, and renowned authority on lower back disorders, has for over 30 years been researching the way problems can arise in the spine, and how best to prevent, heal and strengthen the back. I have been aware of his work for some time, having read his books long ago. (See my review on his first book Low Back Disorders.) When the chance came to study with him in person, I jumped: I attended a weekend workshop with Stu and about 120 or so physiotherapists, chiropractors and other health care professionals. Much of what I learned reinforced what his books described, but three key teachings stood out for me. [1]

1) Intentions Matter!
2) Bracing and Spacing
3) The answer to every health question is, “It depends…”

1) Intentions matter!

One of the great treasures of physical yoga practice is the strength and mobility developed in the spine. We have all seen amazing yogis who can drop back from standing into the Wheel Pose and come back up again. There are several advanced back-bending asanas that are accessible only to people who have developed this great range of motion for the spine, and being advanced postures, they are sought after by yoga students who are working their way deeper into their physical practice. But this pursuit of mobility implies a very different intention than creating physical health: for many students the intention of their practice has transformed into performance and aesthetics. Is this wise? Is this safe?

Most of Stu’s “patients” [2] are either seeking to regain normal, daily function of their lower back or seeking to regain elite status in their specialized sport. He rarely sees average people. In yoga we find the same range of intentions – from people using yoga therapy to regain everyday function to athletes, dancers and performers seeking to get the last possible bit of ability out of their bodies. But Stu’s teaching has made me question yet again – what is so special and magical about enhanced range of motion for the spine? Is it safe? Is it healthy? For the most part, the answer is “no.” Stu has analyzed yoga teacher with serious back problems who cannot, or rather, will not understand that their yoga practice is the cause of their problem.

The spine defined: The spine is the link between the appendicular structures of the arms and legs. It is inherently an unstable column of bones, stabilized by the guy wires of muscles, ligaments and fascia, and stopped ultimately by bone on bone compression of the vertebral facets and processes. It may surprise you to know, but elite athletes are not the strongest athletes nor the ones with extreme ranges of motion of their spine: they gain their power and explosive speeds through working to mobilize their hips and shoulders and stabilize their core. Large ranges of motions are not required for elite performance in sports nor in everyday life. So, why do yoga students crave it so much? Because it looks cool? That is the intention of aesthetics, not optimal health.

All tissues in our body thrive on stress, but at a cost. As we stress tissues their inherent tolerance for stress diminishes. If we continue to hold the stress or repeat the stress constantly, the tolerance of the tissues may reduce to below the applied levels of stress. When this happens, as show in figure 1, injury occurs. The area under the tolerance curve is our capacity to deal with stress. Our tolerance is our ability to withstand a load right now. Our capacity is our ability to withstand a load over time. To be healthy we need to increase both tolerance and capacity to optimal levels, and we can increase these, as shown in figure 2, by allowing a refractory period between stresses. Rest and stress together are the magic formula for regaining and maintaining a healthy spine.

Figure 2: Tolerance decreases as stress is maintained.
Figure 2: Tolerance decreases as stress is maintained.

This theoretical framework works very well for our muscles, fascia and even the bones and cartilage. All our tissues need an optimal amount of stress and rest, but! And this is a big but! Stu believes that this formula does not apply to the intervertebral discs! This may not be 100% accurate, all tissues have some ability to heal, but if we act as if this was true, and thus deliberately try to avoid stressing the discs, we will avoid injury and will hasten our return to normal movement after injury.

Figure 3: With rest, tolerance increases again
Figure 3: With rest, tolerance increases again.

If your intention is to build or maintain a healthy spine, here are two important realizations to build into your yoga practice:

  1. The spine does far better when non-neutral positions are held without any load or accompanying movements
  2. When the spine is loaded or moving, it should be stabilized.

We are safe to move the spine when there is no loading. Thus, in our yoga asana practice, reclining or sitting twists should be safe for most students. Similarly, seated or reclining side bends should be fine for the spine. We can work on acquiring larger ranges of motion for the spine when it is unloaded. Once we require the spine to support the weight of the body, however, we are advised to stabilize the spine before applying the load or making any movement. Wheel Pose, Camel, Bow Pose – all the postures that require us to extend the spine while it is under load – must be done with concerted attention on stabilizing the core of the body before the movement begins. We can expand this consideration to any movement of the spine: flexion, side flexions and twists – stabilize first; stress and move second. Unfortunately for yogis who practice with the intention of performance, this stabilization may reduce their range of motion: it is a trade-off – we can not have both stability and large movements in the spine. Intentions matter, and you will have to choose between performance and health, between mobility and stability. But if health is your goal, then sacrificing the ability to do a drop back into Wheel may be a small price to pay for maintaining a healthy spine for the rest of your days.

Clearly, there are those who can safely do these deep back bends, but they have a genetic predisposition that allows them to do so: they are rare. Most people are not so generously genetically endowed and should not be trying to emulate those who have the right shaped vertebral bones. However, even very flexible people need to take care to make sure that they do not go too far without supporting their spines.


How to safely stabilize the spine was the second key teaching of the weekend for me. Stabilization comes from bracing; a neutral shape comes from spacing. This is an important lesson that I have been applying to my practice and teaching – before moving the spine, build a brace and create space.

Imagine a fishing rod standing on its end: left on its own, it would fall over. To keep it upright, guy wires are needed to brace it, but it would not be very stable if only 2 wires were used: better is to have several arranged all around the pole, as shown in figure 3. Also, the wider the base, the more stability would arise – thus, if you hollow out your belly and reduce the width of your core (by performing a deep uddiyana bandha while doing a posture), you will be reducing stability and risking injury. The ideal brace is wide and equally tense all around the spine. If the guy wire in the front were too tight (the rectus abdominis, for example) it would bend the pole. It is quite common for many fit people to have overly developed rectus abdominis. They worked on their 6-pack abs in the hopes of protecting their lower back, but the result is an increase in stress on the spine because they have reduced the lordosis in the lumbar spine. All sides of the core need to be strengthened, not just the abs in front.

Figure 4: A fishing pole needs guys wires to support it standing upright
Figure 4: A fishing pole needs guys wires to support it standing upright.

The amount of tension in the guy wires can also affect the stability of the spine. We do not need to crank up the intensity to maximum: Stuart’s findings show that around 15 ~ 20% engagement of the core muscles is sufficient to create stability. Going above that level is counterproductive and may inhibit movement. In his book he notes: While stiffness is always stabilizing, force may stabilize or destabilize. The relationship is non-linear. Large increases in stiffness occurs quite early as activation begins, but if the force keeps rising, little additional stiffness is created and the force of the muscles may become large enough to create buckling. Better is to coordinate and balance the stiffness in all contributing muscles [guy wires] than focusing on a single group. [3] This fits with the wisdom of yoga teachers who advise that our bandhas be “subtle” – not rock hard. As we investigate building a brace, remember to ensure that your core is not hard, just firm.

Building the brace while creating space: stand up tall and place your hands on the sides of your belly. (See figure 5.) Arrange your thumbs so they are touching the lowest ribs, and extend your fingers so your little finger is touching the top of your pelvis (technically called the iliac crest.) Try to create as much distance between your thumb and little finger as you can without tilting your pelvis or overly straightening your lower back. That is your space. Now, with your middle 3 fingers, push into the side of your stomach. Next, using your stomach muscles push your fingers away. That is the brace. Again, no need to be rigid; but be firm.

Figure 5: Create a brace and space by placing your hands on your belly, press the fingers into the stomach and push the stomach out against the force of the fingers.
Figure 5: Create a brace and space by placing your hands on your belly, press the fingers into the stomach and push the stomach out against the force of the fingers.

Maintaining your brace with space as you move: Often yoga students will bend their spine when they move the body. A safer approach is to learn how to maintain the firmness and length in their core while moving, but that takes technique and practice. To build technique, it is useful to practice bracing and spacing with very simple movements until the habit is formed. Then you can move safely into more complicated movements while keeping the bracing and spacing. We can learn the basics with a simple movement that de-links motion of the hips and the spine. Start by standing on your knees and begin bracing and spacing (figure 6). Now, slowly, without losing your brace or space, flex at the hips lowering your seat to your heels (figure 6). Again, keeping the spacing and bracing and only moving from the hips, stand back on your knees. You have just done a 90 flexion of the hips without any movement of the spine. Repeat several times to make this habitual. Practice it every day.

Figure 6: Maintain the brace as you flex the hips and sit back on your heels, and then while rising again.
Figure 6: Maintain the brace as you flex the hips and sit back on your heels, and then while rising again.

Bracing and Spacing under Load: When you can keep the spine neutral and firm (but again not hard! Remember 15 ~ 20% engagement) try the next exercise as shown in figures 7 & 8. This “Side Bridge” is one of the “Big Three” that Stuart McGill recommends to develop a strong core without risking the lower back. (See the review of his book Low Back Disorders for a description of the other two.) Just as we did with the first exercise, all movement is coming from the hips, not from the spine. If you feel the spine start to move or lose its brace, you should stop for today and rest. Practicing the wrong technique does not make things better! There is a misconception in the fitness and sport’s field that practice makes perfect – this is not true: practice makes permanent! Only perfect practice makes perfect. Once you lose form, which happens when we get just a little bit tired, you are making permanent poor technique and this leads to injury.

Side Bridge – Level One: Learn the technique first by doing the easy version of this posture. Lie on your side, propped up on one arm with that hand clenched firmly in a fist. If you have any shoulder issues, cap the shoulder firmly with your free hand as shown in figure 7, and pull down. That will help to stabilize the shoulder. If you do not need to use the free hand, position the hand on the side belly and start spacing and bracing. With knees bent, move your hips forward. As you do this, the hips will naturally come up, but do not try to lift the hips up because that will result in a side flexion of the spine, which is what we do not want. Your hips here are the only things moving, just as was the case in figure 4. Practice this movement several times and then hold with your hips forward for 15 seconds. Rest for a moment and then try the other side. Repeat this again with only 10 seconds holds. After resting try one last time for 5 seconds each side. In time, as you get stronger, you can work towards 20/15/10 second holds for each of the three sets, then 30/25/20 etc until you can hold for 60 seconds. {Do not increase the number of sets, increase the time in each set.] Once you can do that, you can try level two of the Side Bridge.

Figure 7: Keep the spacing and bracing as you perform the simple version of the Side Bridge.
Figure 7: Keep the spacing and bracing as you perform the simple version of the Side Bridge.

Side Bridge – Level Two: Now, you can try the pose with both legs straight as shown in figure 8, but feet apart. (Note: Stuart asks that we never stack the legs on top of each other. While legs together in Vasisthasana is common in our yoga world, he does not recommend it.) By now you do not need to repeat the movements up and down, just come into the posture and work towards being able to hold the position for 90 seconds each side. There is no rush to get to that level! More important than holding the pose for a long time is maintaining the bracing and spacing while you are in the pose. Stuart has noticed a clear correlation between athletes who suffer injuries to their spine and the length of time that they can hold the Side Bridge: if you can hold for 90 seconds, you have very little chance of suffering back problems.

Figure 8: Side Bridge advanced version
Figure 8: Side Bridge advanced version.
Never is never right and always is always wrong: While Stuart recommends moving with a stable spine at all times and never stacking the legs on top of each other in Side Bridge, clearly there are strong students who will have no problem with these options. You may be such a student, but as you learn these movements, start easy. Eventually you may wish to modify some of these directions, but do so consciously and with awareness. You are making a choice and, depending upon your intention, that may be great for you. But by staying aware of how your back feels during the posture and in the days after your practice, you will be ready to modify your practice if pain arises, before it becomes a debilitating injury.

Taking bracing and spacing to the rest of your yoga practice: Now that moving your spine with stability has become a habit, you will find yourself doing this in all your movements. When you do a Sun Salutation, as you come into the forward fold, initially with knees bent, you will be moving from your hips. There does not need to be any flexion in the spine as you come forward. Similarly, when you rise up at the end of the Sun Salutation, it will be your hips lifting your upper body, not your spine. Beginners should practice the sitting on the heels movements with a stable spine a couple of times before doing Sun Salutations to remind them of what moving from the hips feels like. Practice the same bracing and spacing every time you sit down in a chair or rise up again getting out of a chair. Move from your hips. In time, you will find yourself bracing and spacing as you move into more challenging asanas such as the Warriors, Chair Pose, even Triangle and Side Angle poses. Finally, even as you deliberately allow the spine to flex or extend in advanced postures, such as the Wheel, you will be habitually seeking that space and stability in the core that will protect your back in the deepest poses.

3) It depends …

The good professor is such a wonderful resource of knowledge and experience that naturally the clinicians in the room wanted to share their cases with him. They would ask, “I have a client who has X, Y, and Z problems what can I do for him?” His answer is the third big lesson I learned that weekend: “I don’t know. It depends” If a man with over 30 years of scientific and practical experience does not know the answer to a person’s problem after only hearing a description of the pathology, how can a yoga teacher with no clinical training at all ever hope to, or dare to, offer a solution to our student’s back issues?

The professor with his trademarked bushy moustache explained that before he can suggest anything for a patient he conducts a 3-hour assessment, reads all the referring doctors’ notes, and talks in detail to the patient about the causes of the pain. All that combined with decades of clinical and laboratory experience gives him a pretty good idea of what to test and try. Yoga teachers, however, have none of that experience and, except for yoga therapists who do take the time to assess and get to know their students in depth, we do not have the time to really understand our student’s biography or biology. Part of the reason for the answer “It depends” is due to the natural and large range of human variations that exist. Stu often commented on how unique our bone structures are compared to other people. (He also shared several photos of variation in the bones from Paul Grilley’s web site. What works for one person’s spine may never work for another person. What works for a prima ballerina may not work for a linebacker in the NFL. What worked for you as a child will not work for you as an adult. (As Stu said, “babies are not miniature adults.”)

For yoga teachers, the safest approach is to “do no harm.” This means, work to teach bracing and spacing and leave enhancing ranges of motion to postures where there are no loads upon the spine and no constant movement required. Every body is different and your body is likewise unique. Your spine needs to move, but when under load and tension, the spine needs to be stable. Choose wisely what works for you and your spine. And if you have low back problems or if you are a yoga teacher who has students who have low back challenges, read Professor Stuart McGill’s books and watch his DVDs. It will be a valuable education.

Given Stu’s experience and studies, it may be that you will begin to re-think Hatha Yoga’s emphasis on extreme ranges of motion. It may be that having a healthy, strong spine will become more important than how bendy your spine can be.


  1. — While I have tried to be faithful to what Stuart McGill taught in the workshop and in his books, any errors in this article are down to me, not Stu.
  2. — Normally scientists have subjects; medical doctor’s have patients – while Stu is not a medical doctor, doctors often send him patients when they have run out of ideas for helping them
  3. — See Low Back Disorders (page 119) by Stuart McGill

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