why does lower back pain occur?

In understanding why back pain occurs it helps to think of three different scenarios – an acute injury, back pain that has gradually gotten worse over time, and chronic/recurrent lower back pain. In all cases underlying factors relating to your anatomy, specific muscle weakness/tension, general health, age related changes and biomechanics may also contribute to your lower back pain. However, a general explanation can be provided in each case:

1. Acute injury to the lower back results when a force (e.g. something you are lifting, an impact in an accident or an incident on the sporting field) causes a strain or damage to tissues of the spine. Depending on the mechanism, one or more tissues of the spine may be injured, including muscle, ligament, nerves, discs/joints or even the vertebrae themselves. In many cases of acute lower back injury movements that involve a twisting or bending motion are involved. Like spraining an ankle, this acute injury results in some tissue damage, inflammation and swelling, resulting in pain and limited movement.

2. In cases where your back pain has built up over time it is usually related to a habitual or repetitive posture or activity. This may be related two work, sport or recreation. Repeating a movement or posture that stresses your back in an unfavourable fashion can lead to changes in the tissues of the spine, such as repetitive inflammation, adaptive tightening of muscles, thickening of connective tissues or even stress fracture. Over time, and combined with age related changes, the tissues may eventually be injured as the repetitive stresses have a cumulative effect, and the way we move our back may become abnormal, both contributing to pain.  Back pain of this nature is like a runner with poor technique – eventually their poor technique results in an overuse injury to their ankle/hip/knee.

3. In cases of chronic/recurrent lower back pain, there is usually an injury (acute or gradual onset ) that lead to pain beginning. However, rather than resolving in the usual timeframe of a few months at most, pain persisted. This persistent pain is driven by changes in our nervous system (brain, spinal cord, nerves). The analogy here is that our body is like a computer, and our nervous system is the software. When we hurt our back our hardware (body tissue) is damaged, and we feel pain. Our body heals this damage, and pain should resolve. However, in some cases the software (nervous system) changes too and we re-program our body to move differently, avoid certain activities and we develop beliefs, fears or anxiety about pain. This can make our pain responses more sensitive, or even produce ongoing pain after our injury has healed! So even after the hardware (body tissue) has been repaired, we are stuck with this glitch in our software (nervous system) that causes problems to remain. This can manifest as chronic or recurrent lower back pain. 

The longer you are living with back pain, the involvement of the tissues reduces, and the involvement of your nervous system increases.


Image credit MPC 2016 (1); adapted from Butler and Moseley 2003 (2).



Whilst discussing why lower back pain occurs, the idea of ‘hip and back alignment’ and ‘slipped discs’ should be addressed. Many people are told that they have lower back pain because their back or hips are out of alignment or they have slipped a disc, and it needs to be adjusted back. If you think back to the anatomy and strength of the spine, this idea of a mis-alignment seems strange. Aside from specific cases of significant trauma, fracture or developmental abnormality (such as a large scoliosis curvature, abnormally shaped vertebrae or true leg length discrepancy) the spine will not be out of alignment. It is too robust and adaptable for this to happen. Furthermore, discs do not slip! The tissues that comprise a disc (nucleus and annulus) can be injured, and the disc may bulge or change in shape slightly, but it never slips. Our backs may be sore and display altered movement, muscle tension or changed postures as a response to pain, but they are almost never mis-aligned as a primary problem in all but extreme and unique circumstances.


Age does not necessarily mean your back will be weak. Jean Stewart (pictured) began weights training at age 83, seen here dead lifting 153lbs. Photo credit: Huntersville Crossfit

From a similar stand point ageing of the spine should also be discussed when talking about the origin of back pain. Many people are also told that their backs hurt because they are old, and their spine is degenerating, and that this is expected. It is true that our backs change as we age – ligaments tend to become thicker, our muscles become less extensible and our intervertebral discs lose height and become less supple. The joints in our spine may also display arthritic changes (3). However, some of these anatomical changes are quite normal – like grey hairs and wrinkles (4). Whilst they can certainly contribute to back pain or injury developing, they should not be considered the sole cause. As the old saying goes, ‘people don’t age, they rot’ – back pain with ageing is also related to changes in physical activity, habitual lack of movement and exercise and the resultant loss of strength, mobility and tissue vitality in the spine. To say that someone’s back is sore purely because they are old would be like saying a car engine broke because it is no longer new. It is the lack of proper servicing and rough driving that breaks a car engine, not its age.


1. Kargela, M. (2016). Science Based Theatrics in Physical Therapy. Retrieved from

2. Butler, D.S, Moseley, G.L, Sunyata. (2003) Explain Pain. Adelaide. Noigroup Publications.

3. Adams, M., Bogduk N., Burton K., Dolan P. (2013). The Biomechanics of Back Pain 3rd Ed. Churchill Livingstone.

4. Brinjikji, P.H., Luetmer, B., Comstock, B.W., Bresnahan, L.E., Chen, R.A., Deyo, S., Halabi, J.A., Turner, A.L., Avins, K., James, J.T., Wald, D.F., Kallmes & Jarvik, J.G. (2015). Systematic Literature Review of Imaging Features of Spinal Degeneration in Asymptomatic Populations. American Journal of Neuroradiology, 36 (4), 811-816. DOI: