Yoga sequences often feature many ‘chest/heart openers’ (backbends) and twists but do not tend to feature so much active flexion of the spine. Often when we forward fold in a yoga class we are encouraged to do so with a “straight back”. A common justification for not focusing so much on spinal flexion in yoga classes can be that since so many us tend to sit in a position of passive flexion for most of the day, at our desks or in our cars, our focus should be on backbends to balance this out. This also goes along with theory that to ‘correct’ slouched sitting posture we must simply stretch the front of the abdomen and chest and strengthen the back body.

In reality things just aren’t that simple. We need to keep moving our spine in its full range of motion in a controlled way to keep it healthy. This includes actively flexing, extending, side bending and twisting our spine. If we avoid flexing altogether our spines can become ‘flexion intolerant’ (meaning that we begin to lose the ability to flex). And in terms of our musculature and soft tissue it is often more effective to stretch and strengthen both the front, the back and the sides of the abdomen and chest.

There is also the widespread belief that flexion is simply bad for our spines and that this movement is the culprit in terms of ‘slipped’ discs and lower back pain. Common phrases in everyday life such as ‘watch your back’ or ‘I’ve got your back’ can add to the incorrect idea that our spines are inherently fragile. This set of fear-based beliefs set people up with negative expectations, which has been linked to poorer outcomes and greater pain (Bialosky et al 2010). Evidence suggests that fear-avoidance beliefs are prognostic for poor outcome in patients with lower back pain and should be addressed in this population to avoid delayed recovery (Wertli et al 2014). A systematic review by Saraceni et al (2020) reported that there is (low quality) evidence that greater lumbar spine flexion during lifting is not a risk factor for lower back pain onset/persistence, nor a differentiator of people with and without lower back pain.

The image below shows and MRI of the lumbar spine in ‘neutral’ on the right versus in flexion on the left. This shows that typically when in a position of flexion, the lumbar vertebrae simply end up stacked directly on top of each other in the vertical plane.

The reality is that spinal flexion is a natural movement that is involved in so many of our everyday activities and it really can’t (or shouldn’t) be avoided. I’m not suggesting that we all suddenly start picking up really heavy objects with fully flexed spines, but if we only ever lift a load with a more neutral spine then we only become efficient at making that particular movement pattern.

While spinal flexion for one student who has a prolapsed disc might not feel so good, it can often feel perfectly fine for another student with the same condition. An individualized approach is key.

It is worth noting that while people who have osteoporosis will benefit from gentle spinal movements, there needs to be a degree of caution here, due to the increased risk of vertebral fracture. Spinal flexion, extension, rotation and lateral flexion should all be practiced in a particularly mindful, gentle and controlled way while limiting the full range of movement. Rolling up from a standing forward fold can put a significant amount of stress on each level of the spine during the transition, so a good option here is to place the hands at the back of the legs to reduce the load or to rise up with a more neutral spine and the hands on the hips.

We are tallest first thing in the morning when the intervertebral discs are their most plump, and we slowly become shorter during day as the discs subtly flatten under our body weight (Botsford et al 1994). Snook et al(1998) suggested that limiting spinal flexion early in the morning is a form of self-care for people with persistent, non-specific lower back pain and can potentially reduce pain. A study by Fathallah et al (1995) reported similar results and concluded that risk of injury was also greater early in the day when disc hydration was at a high level.

Nothing is ever black and white when it comes to movement. The key is to keep exploring all of the movement options that we have available to us, listening to our body and making changes when a movement doesn’t work so well for us or give us the desired outcome.

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References:

Bialosky, J., Bishop, M. and Cleland, J. (2010) ‘Individual Expectation: An Overlooked, but Pertinent, Factor in the Treatment of Individuals Experiencing Musculoskeletal Pain.’ Physical Therapy 90, 9, 1345–1355.

Botsford, D., Esses, S. and Ogilvie-Harris, D. (1994) ‘In Vivo Diurnal Variation in Intervertebral Disc Volume and Morphology.’ Spine 19, 8, 935–940.

Fathallah, F., Marras, W. and Wright, P. (1995) ‘Diurnal variation in trunk kinematics during a typical work shift.’  J Spinal Disord 8, 1, 20-25.

Saraceni, N., Kent, P., Ng, L., Campbell, A., Straker, L. and O’Sullivan, P. (2019) ‘To Flex or Not to Flex? Is There a Relationship Between Lumbar Spine Flexion During Lifting and Low Back Pain? A Systematic Review with Meta-Analysis.’ Journal of Orthopaedic & Sports Physical Therapy 0, 0, 1-50.

Snook, S., Webster, B., McGorry, R., Fogleman, M. and McCann, K. (1998) ‘The Reduction of Chronic Nonspecific Low Back Pain Through the Control of Early Morning Lumbar Flexion: A Randomized Controlled Trial.’ Spine 23, 23, 2601–2607.

Wertli, M., Rasmussen-Barr, E., Weiser, S., Bachmann, L. and Brunner, F. (2014) ‘The role of fear avoidance beliefs as a prognostic factor for outcome in patients with nonspecific low back pain: a systematic review.’ Spine 14, 5, 816-36.