For a long time, the human spine has been viewed as a machine: if you overloaded it with a single excessive force or repetitive loading, there would be ‘wear and tear’ (structural damage, e.g., disc degeneration) and consequently, symptoms such as back pain and sciatic pain.
But is it that simple?
With the emergence of spinal magnetic resonance imaging (MRI), we have been able to investigate spines in greater detail and to further research disc degeneration.
Twin studies (research involving pairs of twins) and spinal MRIs have been particularly helpful in exploring the factors that influence disc degeneration. A key advantage of twin studies is that they remove confounding influences, including age, sex and genetics. So, specific influences, such as the physical nature of occupations, on disc degeneration can be isolated from other influences and thus, more easily studied.
If physical loading causes spinal changes, then people with more physically-demanding jobs (relative to their corresponding twins) should have more disc degeneration.
However, researchers found that pairs of twins tended to have similar spines despite having jobs with different physical demands (44-year-old farmer vs. journalist, 48-year-old plumber vs. programmer, etc.) These findings do not support the idea that spinal changes are just ‘wear and tear’ from use. What appeared to have a greater influence on spinal changes was genetics.
While we are still learning more about the relevance of structural changes in the spine, many changes are common, normal, and not always associated with pain. When built up gradually, movement and loading are safe and healthy for your spine.
- Battié et al. (2009) (PMID: 19111259)
- Brinjikji et al. (2015) (PMID: 25430861)
- Urban & Fairbank (2020) (PMID: 32000991)
- Image from https://commons.wikimedia.org/wiki/File:Team_Lifting.jpg