What do we mean when we talk about “compression” of the spine?

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.

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, disc herniations may well just be a part of our natural aging process.

What does “decompression” of the lower back look like then?

We cannot actively create space between our vertebrae. While there is widespread belief that we can lengthen our spine i.e. actively move the vertebra further apart from each other and grow taller, we simply can’t.

There are no muscles that work to draw the vertebrae apart. When we use gravity, for example in a standing forward fold, it’s unlikely that additional space is created here either. The jury is still out on this one. (What we can do however is elongate the spine by diminishing our natural curves i.e. attempting to straighten our spine.)

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.

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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.