Does sitting cause back pain? Flipping and flopping over the years

Back in the day, I believed that sitting a lot was definitely a risk factor for back pain.

Why did I think that? It was entirely based on my “common sense” as a massage therapist, seemingly confirmed by observation of my (very skewed) patient data sample. And so, for more than a decade, I warned a great many PainScience.com readers to beware of too much sitting.

Eventually I noticed that the evidence really didn’t back up my common sense. Does it ever? And so, in 2017, I officially changed my mind. Flip-flop! I followed that evidence, like any self-respecting science journalist should do! I made a bit of a blogging meal out of confessing my mistake. (Mea culpa posts are always popular.)

I got to work citing the science, which remains fairly persuasive to this day: many studies all showing no correlation whatsoever between sedentariness and back pain. And so my warning tune was changed …

Before: Warning people about the dangers of sitting.

After: Warning people about the dangers of believing in the dangers of sitting! Specifically, of believing backs are so fragile that they can be hurt by mere sitting.

But it wasn’t over. I had missed a study. A good one. Something that was probably better than anything else I was citing. And, curses, it supported my original bias, and contradicted my new, evidence-based bias.

Ruh roh! Flop-flip?

Measuring total laziness with accelerometers

Gupta et al was the first-ever study of the relationship between back pain severity and objectively measured total sitting time — not just sitting at work, and not just measured by self-report, but by accelerometers. They collected data back pain intensity from 200 blue collar workers in the month before the experiment, and then they measured their typical sitting behaviour over four days.

There’s some heavy-duty number crunching in this one, which makes it harder to evaluate. There’s plenty of room for flaws to hide in all that math, but there’s certainly nothing obviously wrong with the study. Seems like good methodology to me, likely to produce more reliable results. Unfortunately, a decade later, it is still the only study using this methodology, so it still really needs to be replicated — all the more so because it is reporting results that are at odds with all the other studies, even if their methodology was obviously inferior.

Innovation in this kind of research is rare, and doesn’t always give us a better answer. Maybe this experiment was the happy exception: a new way of studying the problem that finally produced a better answer than previous research could. It certainly looks that way.

Or maybe it’s just more noise. And that is why we (still) need some replication.

Sitting too much at work versus sitting too much anywhere: an odd contradiction

The study showed a clear risk of back pain from lots of sitting of any kind. For instance, for the serious sitters, the risk of strong back pain was three to five times greater than it was for the lounging lightweights. That’s a strong signal! But that strong signal is missing in action for people who sit a lot at work. Not just less risk, but no statistically significant risk at all for those folks. Odd!

I’m not sure what to make of that. Every dataset has weird subsets, but why would that subset be anomalous like that? Work tends to aggravate problems, not help them (for instance, see Pronk, showing that activity that’s helpful at home tends to more injurious at work). Regardless, if sitting in general really does greatly increase the risk of back pain, then you’d expect to see at least some risk in any sample of sitters.

Not saying this is a deal-breaker, but it is a bit of a head-scratcher. And another reason replication is (still) needed.

Flop-flip or not?

Gupta et al continues to annoyingly but credibly contradict the shiny new evidence-based position that I made a public fuss about adopting back in 2017. If these results can eventually be reinforced by other studies, then it will be my first-ever example of following the evidence back to a previously abandoned position — undoing my flip-flop.

So far I’ve been spared that embarrassment by the lack of replication.

It’s not truly embarrassing, of course. This is just more of the legendary uncertainties in the pain business. Obviously, the only correct “position” here is to report the uncertainty — rather than overconfidently declaring either that it’s a myth that sitting causes back pain … or that it does. We just don’t know.

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This study was long ago cited in an update to PainScience.com’s huge science-based guide to back pain, which is like a compilation of twenty years’ worth of blog posts like this, a 200,000-word beast … but more organized than just a pile of posts. It’s written for both patients and professionals, like all my content. Read the large, free introduction.