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Only quantity of exercise for back pain produces better results

PainSci » bibliography » Ferreira et al 2010
Tags: back pain, exercise, counter-intuitive, pain problems, spine, self-treatment, treatment

One page on PainSci cites Ferreira 2010: The Complete Guide to Low Back Pain

PainSci commentary on Ferreira 2010: ?This page is one of thousands in the bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.

Studies of exercise for low back pain are often a bit underwhelming: some of them show some benefit, but it’s never a big deal. We’re always left wondering if another way of exercising (or testing) might have worked out better. There are so many ways to exercise, and the science of exercise therapy is generally plagued by this complexity: no matter what the research says, there’s always the real possibility that you might get better results by dialing up a different combination of variables.

This statistical analysis of a whole bunch of exercise experiments tried to identify not only if exercise works for back pain, but (importantly) which variables matter. This is quite different than testing to see what kinds of exercise work (and we already know there is no obviously superior exercise for back pain). The point was to see which variables affect study outcomes the most, including things like customization of the exercises and supervision. They found only one that stood out: “only dosage was found to be significantly associated with effect sizes.” Nothing else mattered very much, just how much exercise was done. Specifically, the number of exercises sessions. Quantity, not quality?

And even that didn’t matter much. The effect of exercise was small in any case — real, but small. In fact, the effect on pain was barely there: “arguably these effects were too small to be of clinical significance.” The effect on disability was a little more promising, thankfully.

These results suggest that second guessing what kind of exercise therapy to do for what patients might be bit of a fool’s errand: it doesn’t much matter who does what, just that you do it. If you do enough, you’ll probably get some benefit. But there’s also a real problem of diminishing returns: a large dose of exercise doesn’t (usually) produce a large benefit. But it will probably secure a modest benefit, at least.

~ Paul Ingraham

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

BACKGROUND: Exercise programs may vary in terms of duration, frequency, and dosage; whether they are supervised; and whether they include a home-based program. Uncritical pooling of heterogeneous exercise trials may result in misleading conclusions regarding the effects of exercise on chronic low back pain (CLBP).

PURPOSE: The purpose of this study was to establish the effect of exercise on pain and disability in patients with CLBP, with a major aim of explaining between-trial heterogeneity.

DATA SOURCES: Six databases were searched up to August 2008 using a computerized search strategy.

STUDY SELECTION: Eligible studies needed to be randomized clinical trials evaluating the effects of exercise for nonspecific CLBP.

OUTCOMES: Of interest were pain and disability measured on a continuous scale.

DATA EXTRACTION: Baseline demographic data, exercise features, and outcome data were extracted from all included trials.

DATA SYNTHESIS: Univariate meta-regressions were conducted to assess the associations between exercise effect sizes and 8 study-level variables: baseline severity of symptoms, number of exercise hours and sessions, supervision, individual tailoring, cognitive-behavioral component, intention-to-treat analysis, and concealment of allocation.

LIMITATIONS: Only study-level characteristics were included in the meta-regression analyses. Therefore, the implications of the findings should not be used to differentiate the likelihood of the effect of exercise based on patient characteristics.

CONCLUSIONS: The results show that, in general, when all types of exercise are analyzed, small but significant reductions in pain and disability are observed compared with minimal care or no treatment. Despite many possible sources of heterogeneity in exercise trials, only dosage was found to be significantly associated with effect sizes.

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