Should we lengthen the spine in every yoga asana?
“Lengthen your spine” is a popular cue amongst yoga teachers. It is something that I used to say all the time when I was teaching, but when I started to look more closely at the biomechanics of this action, I quickly realised that it wasn’t as simple as I had once imagined.
Firstly, it can be easy to assume that we can indeed lengthen our spine, i.e., actively move the vertebra further apart from each other and grow taller as a result, but there are in fact no muscles that are able to make this action happen. It is also unclear if traction, for example using gravity in a long-held standing forward fold, can increase the space between adjacent vertebrae either. We can however diminish the curves of the spine (attempt to straighten it), and this will have the effect of elongating it. But what benefits are to be had from constantly doing this throughout a yoga class and why has this become such a popular cue?
The obsession with “lengthening” the spine has probably arisen because so many people tend to slouch when they sit or stand. While it doesn’t tend to be effective to initiate spinal movements from a slouched position, it isn’t particularly effective to initiate spinal movements from an elongated position either. Moving from a more neutral position is often a better place to start. You can explore your neutral range by slouching followed by straightening and settle with a position in between these two extremes.
I imagine that the desire to continuously lengthen the spine is also associated with the idea of “decompressing” the low back. However, our spines naturally compress and decompress within each 24-hour period. The intervertebral discs that are located between our vertebrae have the dual role of providing the primary support for the vertebral column while possessing enough elasticity to permit the required mobility of the spine. The discs accounts for 25% to 30% of the overall height of the spine. We are tallest first thing in the morning when the discs are their most plump. This isn’t necessarily a good thing because when the discs are this plump they are not as efficient at offering support. This is one reason why (often intuitively) it is not a great idea to make excessive movements of the spine as soon as we crawl out of bed. We slowly become shorter during the day as the discs subtly flatten under our body weight (Botsford et al 1994) and the discs are able to offer more support and facilitate the movements that we choose to make. In this sense a degree of compression of the discs throughout the day is completely natural.
Neck stretch in yoga
Do people equate spinal compression with herniated discs? An intervertebral disc herniation occurs when part of a disc pushes outward beyond its normal boundaries. The prevalence of prolapsed discs has been shown to increase with age (Brinjikji et al 2015). While in some cases a disc herniation can lead to spinal cord compression, in the majority of cases there is no correlation between a herniation and lower back pain (Beattie 2008). We now realise that up to 50% of prolapsed discs can spontaneously repair (Chiu et al 2015). Therefore, many cases of disc herniations are simply part of our natural aging process.
Apart from the fact that I haven’t even been able to get clear about what people mean when they talk about compression of the spine, what would “decompression” of the spine even look like? We have already discussed that we cannot actively create space between our vertebrae. Attempting to decompress the spine passively doesn’t appear to be effective either. A systematic literature review by Macario and Pergolizzi (2006) concluded that the efficacy of spinal decompression achieved with motorized traction for persistent discogenic low back pain remains unproved. A double-blind, randomized controlled trial by Demirel, Yorubulut and Ergun (2017) showed that patients with lumbar disc herniation had no significant improvement based on clinical and radiologic evidence following non-invasive spinal decompression therapy compared to the control group.
Personally, I strongly believe that the best thing that we can all do for our spines is to move them with control, through their full range as often as possible. This is where yoga can be so powerful. Movement is often the precise medicine that we need. Try spending less time focusing on lengthening your spine and more time moving it!
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References:
Beattie, P. 2008. “Current Understanding of Lumbar Intervertebral Disc Degeneration: A Review With Emphasis Upon Etiology, Pathophysiology, and Lumbar Magnetic Resonance Imaging Findings.” Journal of Orthopaedic & Sports Physical Therapy 38(6): 329–340.
Botsford, D., Esses, S. and Ogilvie-Harris, D. 1994 “In Vivo Diurnal Variation in Intervertebral Disc Volume and Morphology.” Spine 19(8): 935–940.
Brinjikji, W., et al. 2015. “Systematic Literature Review of Imaging Features of Spinal Degeneration in Asymptomatic Populations.” American Journal of Neuroradiology 36(4): 811-816.
Chiu, C. et al. 2015. “The Probability of spontaneous regression of lumbar herniated disc: a systematic review.” Clin Rehabil 29(2): 184-195.
Demirel, A., Yorubulut, M. and Ergun, N. 2017. ”Regression of lumbar disc herniation by physiotherapy. Does non-surgical spinal decompression therapy make a difference? Double-blind randomized controlled trial.” Journal of Back and Musculoskeletal Rehabilitation 30(5): 1015-1022.
Macario, A. and Pergolizzi, J. 2006. “Systematic Literature Review of Spinal Decompression Via Motorized Traction for Chronic Discogenic Low Back Pain.” Pain Practice 6:171-178.