Are Dangling and Rolling-up Safe?

Excerpted from Your Spine, Your Yoga
By Bernie Clark
March 22, 2024

Must the knees be bent whenever we do a forward fold? Let’s start with the definitive answer: yes, no and maybe! This question leads to a lot of discussion and controversy. The problem begins with the fact that there is no right answer that works for every body. The main concern centers around the amount of stress occurring in the spine when a yoga student performs a forward fold. On the one hand, we have the belief that if the lumbar spine is flexed, the stresses along the spine are much greater than if the lumbar remains in a neutral position. (Interestingly, there is more stress in the spine when we come up from a forward fold than when we go down.¹) That concern leads to the commonly heard cue, “Bend your knees when you fold forward.” The logic behind this suggestion is that when the legs are straight, tight hamstrings will reduce the amount of hip flexion available, forcing students to round their backs to fold forward.

Due to a spinopelvic rhythm, almost everybody begins a forward fold with some flexion of the spine, and then flexion of the hips.³ But there are several problems with the logic that we must bend our knees when we fold forward or come up:⁴

1. Bending the knees is no guarantee that the lumbar spine will retain its neutral, lordotic shape. (See figure 2.)
2. Some students’ hamstrings are loose enough to allow them to do full flexion at the hips without bending the knees.
3. Having the legs straighter creates and maintains tension in the hamstrings and adductor muscles, which will help to extend the hips when we come up again.
4. Most healthy students have spines strong enough to tolerate the stress of folding forward with a fully flexed spine.
5. But in any case, a fully flexed spine disengages the erector muscles, allowing the fascial tissues to take up the stress without any compression penalties.
6. Having less bend to the knees can be protective for people with knee problems.
7. If you don’t allow students a chance to strengthen the spine through this movement, when will you let them work their back muscles?

WHEN BENDING THE KNEES IS A GOOD IDEA

Not everyone needs to worry about bending their knees or even keeping the spine neutral when performing a forward fold—it depends upon the person, her biology and biography, how flexible she is in the hips, how many times she is doing the movement and over how many years, how quickly she moves, where the arms are (reached out overhead, to her side or holding her hips), whether she has a slight build or is heavy in the upper body, how much core muscle co-contraction she uses and several other factors.⁵ But how do you know whether this movement is safe for you? Forget all the theoretical arguments, studies and demographics—is folding forward with a flexed spine a good thing for your body? Should you bend your knees and keep your spine straight? There are definitely situations where bending the knees is a good idea. Here are a few of them:

1. When you have back problems;
2. When you cannot flex from the hips enough to get your hands to the ground;
3. When engaging the thighs to keep the legs straight creates impingement during a forward fold;
4. When you are picking up a heavy object;
5. When you are tired or have done a number of forward folds already; and
6. When you are preparing for a quick movement.

ROLLING UP AND ROLLING DOWN

An issue related to the question of whether we should bend our knees and keep our spines straight in forward folds arises in the yoga practice of rolling up (or down) from a forward fold. Many teachers warn their students to “never do this!” The same fear is expressed as with using straight legs during forward folding: there will be too much stress in the spine. But again, when the spine is fully flexed, the fascial tissues and ligaments hold the upper body; when the fascial tissues are taking up the stress, they do not create compression along the axis of the spine.⁶ Another reason this is less stressful than a forward fold with a straight upper body is that the moment arm of the upper body is reduced compared to with a straight spine; with a notable curve to the spine, the distance from the L5/S1 joint to the top of the head is shorter, which reduces the amount of stress the spine experiences. Additionally, the roll-up or roll-down is done very slowly, which has been shown to be less likely to injure or damage ligaments and discs.⁷ Indeed, in the Pilates world, the roll-down and roll-up, as shown in figure 3, are often offered as first and last exercises in the practice.⁸ A beginner’s Pilates version of the roll-down is to have a slight bend in the knees, but a more advanced version is to have the legs increasingly straighter.

One safer variation of rolling up or down is to keep the hands behind you as you roll, sliding them down the backs of the legs; this will further reduce the upper body’s moment arm and thus the stress along the spine. Most normal, healthy spines can slowly roll up and down without risk, but this may not be a great practice for someone with spinal problems. The key, once again, is to determine whether this is a good idea for you, given your biology and biography. It is a low-risk, low-reward movement that should be fine for most people, but if you decide you don’t want to take any risk and prefer to forgo this movement, that is quite fine too. Just make sure you select some of the other ways to strengthen and mobilize your back that are low risk and have higher rewards.

SUMMARY

An answer of “yes, no and maybe” is not very helpful when addressing questions about whether we should allow our spine to flex or not, but it is true that “it all depends” upon the student and the movement. However, if you want some generalized rules of thumb, here is a list based mostly on the work of Greg Lehman, a physical therapist based in Ontario, Canada.⁹ These are not without controversy, so pay attention to how you feel, and if these rules don’t work for you, adapt.

• • When flexion is accompanied by a low load, there is no flexion fear. This includes bending over to pick up a light object off the floor, to tie your shoes or to do a forward fold (Uttanasana) in a yoga class.
  • When flexion under low load is repeated a lot, there is no flexion fear. Think here of doing 108 Sun Salutations—while there may be many other reasons not to do them,¹⁰ a fear of hurting your back should not be one.
  • For flexion under a heavy load, regardless of how many repetitions are required, use a neutral spine. In these cases, hone your technique so that your spine remains as close to neutral as possible, for as long as possible, and engage your abdominal brace—but don’t overdo it!¹¹
  • Avoid jerky movements and fold smoothly. Slower is safer and reduces peak forces generated by the muscles.
  • When pain arises during flexion, then don’t do any flexion, at least not while you have pain. Heal. When you are healed, reintroduce flexion with no load and few repetitions until you have regained strength and endurance.

If you are lifting an object, rather than simply managing your own body weight, here are a few more suggestions:

• • Whenever possible, have the feet apart, not together. Feet shoulder width apart or slightly wider works better than having the feet together. This provides greater stability for the body overall and reduces the risk of falling when picking up heavier objects. (Thus, the idea that our feet must be together when we do a forward fold doesn’t work for everybody; please consider whether it is best for you.)
  • Reduce the distance between you and the object being lifted. The closer the object is to your core, the shorter its moment arm and thus the less stress there is along the spine. Ideally, the object is between your legs (and not far away as shown in figure 2).
  • Avoid twisting the spine while lifting. Adding a twisting torque to the discs while they are already being compressed is not a great idea.
  • When the load is high, keep the spine as close to neutral as possible. Too much flexion risks damaging the discs, while too much extension risks damaging the facet joints.

The last point refers to either flexion or extension, but again let’s be clear—this may not be a problem for every body in every situation. For some people, a moderate amount of flexion may be protective, as it can reduce the compression generated by the big back extensor muscles. A moderate amount of extension may also be protective because the facet joints are in their closed-packed position, which makes them more able to resist stress. However, the key is “moderate”; once the amount of flexion or extension approaches maximum, these benefits are lost and risk increases.¹²

So, should you bend your knees when you lift something or fold forward? Yes! No! Maybe? It depends…

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Footnotes:

[1] See G.A. Mawston and M.G. Boocock, “The Effect of Lumbar Posture on Spinal Loading and the Function of the Erector Spinae: Implications for Exercise and Vocational Rehabilitation,” New Zealand Journal of Physiotherapy 40.3 (2012): 135–40.

[2]> The photo is courtesy of Mawston and Boocock, “The Effect of Lumbar Posture on Spinal Loading and the Function of the Erector Spinae: Implications for Exercise and Vocational Rehabilitation,” New Zealand Journal of Physiotherapy 40.3 (2012): 135–40.

[3] In the literature, the spinopelvic rhythm is sometimes known as the lumbopelvic rhythm, as when the pelvis moves, so does the lumbar spine and vice versa. Limitations in lumbar range of motion will quite often affect the range of motion available to the pelvis at the hips

[4] Each of the following seven points are elaborated in the book, Your Spine, Your Yoga.

[5] See Mawston and Boocock, “The Effect of Lumbar Posture.”

[6] Ibid.

[7] See Michael A. Adams, Kim Burton, and Nikolai Bogduk, The Biomechanics of Back Pain, 3rd ed. (London, UK: Churchill Livingstone, 2012), 152.

[8] See Allan Menezes, The Complete Guide to Joseph H. Pilates’ Techniques of Physical Conditioning, 2nd ed. (Alameda, CA: Hunter House, 2004), 63.

[9] Greg Lehman is a physiotherapist and chiropractor treating musculoskeletal disorders within a biopsychosocial model. See his website at www.greglehman.ca/bio.

[10] I personally am not a fan of 108 Sun Salutations due to the repetitive stress under load on the wrists during the transitions to Up Dog and Down Dog, but not because of fear for the spine.

[11] For a description of how to do bracing and spacing in the core, see the article 3 Things I Learned From a Weekend with Spine Biomechanic Stuart McGill.

[12] See Neumann, Kinesiology of the Musculoskeletal System, (Maryland Heights, MO: Mosby, 2002), 349.