I’m sure you’re well aware of the overwhelming amount of information that tell us we have to be physically active to be healthy, right?  It’s true being sedentary is not good for us.  And indeed the evidence to demonstrate the wide-reaching benefits of physical activity on health is irrefutable. From depression to blood pressure, insulin resistance to the risk of falls, the evidence all points to getting off yer backside and moving!

Incidentally, I love this video by Dr Mike Evans that illustrates perfectly the benefits of exercise.  I recommend it whenever I can; it has nearly 6 million views now!  Can you limit sitting for just 23.5 hours a day…?

How Much Exercise Is Enough?

This is a great question, and not just how much, what type of exercise? Dr Evans shows the evidence for just 30 minutes of activity a day is enough to bring about health benefits (compared to being sedentary!). So does it count if you have a physically active job?

Well it might, however, it might not!  I read a really interesting article in the British Journal of Sports Medicine recently called the Goldilocks Principle (click to access article).  The authors discuss the variables, such as activity intensity, type, frequency etc. that are important to achieve the ‘just right’ (hence the Goldilocks principle) dose of exercise to elicit a health promoting effect. Importantly, they look at this from a work perspective.  Whilst some of us sit on our arses for a living (well not quite, but you get the gist), many have a job that requires a lot more physical work than tapping at the keyboard.

Why Physical Labour Might Be Bad For You

There’s the obvious risk of musculoskeletal injury and accidents in professions such as construction etc. but I’ll leave this for another time. The really thought-provoking bit for me was the higher levels of poorer health in workers in jobs that involve a lot of physical activity compared to workers with very little physical activity at work. They gave a great example of a cleaner. Whilst cleaners have long continuous periods of physical activity, it’s at low metabolic intensity, this means the activity is insufficient to promote cardiorespiratory fitness gains but absolutely long enough to cause fatigue. The worst combination!

It also reminded me of some of the key papers that directed my PhD work. An eminent professor, Moshe Solomonow (look him up!), cleverly demonstrated back the late 1990s / early 2000s the detrimental effects of low level tissue loading, such as leaning over a conveyor belt on an assembly line, on ligament and muscle performance. It’s no wonder these workers suffer from low back pain. Loading over a period of time causes the tissues to stretch (called creep) and the muscles to fire in a disordered pattern, which over an 8-hour shift is unlikely to recover. These effects cumulate over a working week.

What’s The Answer?

Unfortunately there isn’t a single resolve to this problem. However, at the very least I hope it provides food for thought. Physical activity is most definitely good for health, but repetitive and prolonged, low level loading probably isn’t. As such we have a responsibility to think more carefully about how we can minimise the stresses to those who perform the under-valued yet highly valuable work that keeps the economy going.

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