From identical twins to half a million Norwegians: how we misunderstand the impact of physical work on our bodies.
If you had to guess the average time it takes for medical research to make it into everyday practice, how long would you guess?
A year or two? Five? Surely no more than 10!?
Soberingly… the average lag time from discovery (research) to implementation (practice) is close to 17 years¹. A truly glacial pace - one that leaves plenty of opportunity for out of date advice to hang around (like milk being good for bone density!).
Old science and limiting beliefs
In the Western world, we tend to think of our bodies as being somewhat fragile - that they are prone to injury if we don’t move perfectly. We also have an underlying assumption that using our bodies somehow wears them out… that we can only be physical for so long, before our bodies (and joints) give out on us.
You’ll find this belief reinforced strongly in physical industries (construction / manufacturing / resources) where you’ve got multiple generations on the same site. The old blokes are sore. They tell the young ones to suck it up, that it’s just part of the job. For young workers, this cultural attitude can be understandably bleak.
But there’s room to be optimistic. It turns out that wear and tear is not what we think it is. In fact, it may not exist at all.
Studies, humans and common sense
Our attitude to wear and tear is in stark contrast to what we know is true from a large body of evidence on the human condition. We know that exercise is good for us. We know that our body self heals (a bruise fades, a tear heals). We know that lifting weights is deliberately trying to break down muscle, so that it will grow back bigger and stronger.
We also know that sitting around all day is bad for us… so why is physicality seen as the more damaging force? Yes we can point to high injury rates in physical industries, but there is a wealth of literature out there that shows there is more to it than simply job descriptions.
The Norway Study
A 2021 study² of almost 500,000 workers in Norway, spanning 3 decades, showed that men whose jobs required frequent moving and lifting, were more likely to outlive their deskbound counterparts. Interestingly, there was no correlation found for women - those in physical occupations had the same life expectancy of those in sedentary roles.
The Twin Study
The ‘Twin Studies’³ were a series of studies exploring the relationship between occupation and spinal health in identical twins. The goal was to validate whether physically demanding work led to more ‘wear and tear’ on the spine.
Remarkably, these studies demonstrated that a physical job had no meaningful effect on spinal health:
‘The once commonly held view that disc degeneration is primarily a result of aging and "wear and tear" from mechanical insults and injuries was not supported by this series of studies. Instead, disc degeneration appears to be determined in great part by genetic influences. Although environmental factors also play a role, it is not primarily through routine physical loading exposures (eg, heavy vs. light physical demands) as once suspected.’⁴
The problem with scans: Slipped discs and other porky pies
Ok ok, let’s say that you know someone with a bad back. Maybe they had a disc bulge, maybe it’s bone on bone. The scans showed it’s bad. It’s nothing to do with twins or living longer… it was a ‘real injury’ with a scary diagnosis.
It turns out that the majority of us have signs of degeneration in our spines and joints. In fact, a number of studies have clearly shown that this type of spinal ‘wear and tear’ - the one we most fear - has no correlation to pain or injury.
One 2015 study⁵ showed that 68% of people aged in their 40’s (with no pain) showed spinal degeneration. Another study⁶, this time scanning the necks of people without pain, showed a whopping 73-78% of people aged in their 20’s have disc bulges in their necks. The numbers go up with age but again I’ll stress, these scans are not of injured people, nor are they scans of only people in physical jobs. These are normal healthy spines, in normal healthy people.
Often, when someone is in pain, or an injury occurs, old school wisdom is to get a scan. Even if the doctor knows it isn’t necessary, the patient will demand it, assuming they are doing the right thing for an accurate diagnosis. The scan summary comes back, and hey presto, there are signs of degeneration etc. For many of us, this is where the fear really kicks in. It’s where we stop moving and start self medicating.
In reality, these signs of ‘wear and tear’ were present before the injury, will be there after the injury, and are incredibly unlikely to be playing any role in the issue at all, except for scaring us into unhealthy behaviours.
Building resilience, rather than avoidance
These studies (and many others) help us challenge some of our deeply held (and often limiting) beliefs that physicality is in itself a primary risk to the health of employees.
Where once we saw single-minded focus on reducing load, reach, and asymmetry in tasks, we’re now seeing industry leaders calling out the role of culture, communication and de-stigmatisation as being levers for change. A new focus on health literacy & self care is emerging.
As health and safety practitioners, we can lay the foundations of a culture that responds to pain - not just with fear that it may escalate to a claim - but as simply a part of human experience. One that, like anxiety or stress, can be mediated through interventions that focus on better work design, building capacity and increasing resilience.
Happy moving, Matt
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¹Mark S. Bauer, JoAnn Kirchner, Implementation science: What is it and why should I care?, Psychiatry Research, Volume 283, 2020
⁵Brinjikji, W et al. “Systematic literature review of imaging features of spinal degeneration in asymptomatic populations.” AJNR. American journal of neuroradiology vol. 36,4 (2015): 811-6. doi:10.3174/ajnr.A4173
⁶Nakashima H, Yukawa Y, Suda K, Yamagata M, Ueta T, Kato F. Abnormal findings on magnetic resonance images of the cervical spines in 1211 asymptomatic subjects. Spine (Phila Pa 1976). 2015 Mar 15;40(6):392-8. doi: 10.1097/BRS.0000000000000775. PMID: 25584950.