Detailed guides to painful problems, treatments & more

Three painful science snacks: weekend warriorism, exercise for back pain, and calcific tendinitis

 •  • by Paul Ingraham
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Weekly nuggets of pain science news and insight, usually 100-300 words, with the occasional longer post. The blog is the “director’s commentary” on the core content of a library of major articles and books about common painful problems and popular treatments. See the blog archives or updates for the whole site.

Quick looks today at three randomly selected recent studies with interesting results:

  1. The “weekend warrior” exercise pattern is just as good at delivering health benefits as regular exercise.
  2. Exercise does not show much benefit for acute back pain.
  3. Lavage (scraping) of calcific tendinitis didn’t beat a sham.

DISCLAIMER: My science snacks are summaries, just reporting what was reported in a journal, not analyzing (yet), and not getting into the context (yet). Many caveats apply! House rules: Please do not shoot the messenger, but please do point out study flaws if you see ’em.

If you can’t exercise all week long … going to “war” on the weekend is probably good enough

There’s a long-running debate about how often we need to exercise in order to mitigate the substantial harms of sedentariness (“sitting is the new smoking”), and specifically whether the “weekend warrior” pattern is enough. This new study of 150,000 Mexicans by O’Donovan et al showed literally identical risk of dying from any cause in both weekend warriors and regular exercisers. (“All-cause mortality” being the usual way of measuring general exercise benefits.)

This is a persuasively large data set, with quite reassuring implications for weekend warriors!

However, they also noted that — regardless of timing — there was much more benefit if workouts were “at least 30-60 minutes.”

Screenshot of abstract for Odonovan et al. 2024, with several phrases highlighted in yellow, and one in red: “even busy adults could benefit from taking part in one or two sessions of exercise per week.”

Despite the junky evidence, there’s very little sign that exercise helps back pain

This Cochrane review of exercise for back pain may still have some useful implications, despite “very low quality evidence” it had to work with. Garbage in, garbage out? Certainly a concern with all reviews like this, but it’s also just kind of interesting how crappy the evidence is on this topic! “Many RCTs had a high risk of bias, were small in size and/or there was substantial heterogeneity [all over the place].”

Bias in trials tends to lead to overstating results, so if you can’t produce a positive result with your thumb on the scale, that’s somewhat telling in itself. And these studies, despite being biased in a pro-exercise direction (likely), showed … bupkis, just no effect at all.

This is just one analysis, and obviously the It Depends factor here is huge, but presumably all of these studies looked at some kind of exercise that was a good idea for back pain in some way. While a lack of short term results isn’t exactly shocking, it’s still at odds with the popular idea that exercise is good for back pain. Bear in mind that people are routinely prescribed all kinds of exercises for acute back pain, and everyone — realistically or not — hopes for results within days or weeks, not months. And this is not the first data pointing this way.

Screenshot of abstract for IJzelenberg et al. 2024, with several phrases highlighted in yellow, and one in red: “Exercise therapy compared to sham/placebo and no treatment may have no clinically relevant effect on pain or functional status in the short term in people with acute non-specific low back pain.”

Fake surgery for crispy tendons the same as the real deal

Calcific tendinitis is an unusually painful kind of tendinitis — as I know all too well. I had it a few years ago, and I suspect it will hold the record for my most painful experience for a long time. 0/10, do not recommend.

The tendon gets a bit “crispy” with deposits of calcium, and a common treatment approach has been to surgically “clean” the tendon (lavage). But more and more common orthopaedic surgeries are being tested against shams and losing … and now you can add this one to the list. The details of their methods are a bit of a brain-teaser (they also mixed some steroids into the recipe), but the bottom line is that real lavage didn’t beat fake lavage.

If we have learned anything from the last three decades of rehab research, it’s that we often can’t fix “obvious” problems by trying to remove the obvious part. The likely implication here is that calcification is just the tip of the pathological iceberg that makes the condition suck.

Screenshot of abstract for Moosmayer et al. 2023, with several phrases highlighted in yellow, and one in red: “no benefit for ultrasound guided lavage with a corticosteroid injection … compared with sham treatment.”

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