John: Hello, I'm John Hilton, senior editor at Cochrane. Chronic low back pain is a very common health problem and there are many relevant reviews in the Cochrane Library. A new review, of nearly 250 studies of the effects of exercise, was added to the Library in September 2021. Toby Lasserson, Deputy Editor in Chief of the Library spoke with lead author, Jill Hayden from Dalhousie University in Halifax, Canada about the review and its findings.

Toby: Hello Jill and thanks for talking to us about your review, which is one of the largest in the Cochrane library. Perhaps you could begin by telling us a bit about the question tackled by the systematic review?

Jill:  Thanks Toby. What we set out to do was determine if exercise improves pain and functioning for people with chronic low back pain when compared to no treatment, other common treatments or usual care, which is the type of care you would commonly receive when you visit your family doctor.

Toby: We've all had aches and pains in our back, which might explain the large number of trials of exercise for low back pain and so why is this review so important?

Jill: Low back pain is a leading cause of disability across the world and when it's chronic or long-lasting, it's expensive in terms of healthcare costs and lost working hours. Exercise is promoted in many guidelines and is often recommended for and used by people with chronic low back pain, but past systematic reviews have found only small treatment effects, with considerable variation across individual trials. In recent years, there have been many new trials on the topic, with some concerns about study quality, so it was important to systematically identify and synthesize all this evidence to come up with up-to-date conclusions.

Toby: That was clearly a large task with so many included trials. Can you tell us a bit more about those trials?

Jill: To start, there were even more trials than the 249 we included. We actually found 279 eligible randomized trials but excluded 30 because of research integrity concerns.
The 249 trials that we did include represent over 24,000 people, with an average age of just under 44 years and 59% were women. More than half the trials compared exercise to a non-exercise treatment, with a typical program being a standardized core strengthening program delivered 1-on-1 with a healthcare provider or in a group, with a median treatment time of 12 hours over 8 weeks. Most studies measured pain and disability outcomes, but only 12 studies reported detailed data about adverse effects. 

Toby: I'm sure there are a lot of interesting findings from a review of this size. What do you see as the key 'take home' messages?

Jill:  First and foremost, we found that exercise is likely to be effective for chronic low back pain. Overall, three months after the start of treatment, people receiving exercise treatment rated their pain an average of 15 points better on a scale of 0 to 100 and their disability 7 points better compared to people who had no treatment or usual care. Looking into subgroups: we found that exercise treatment is probably more effective than advice or education alone, or electrotherapy; but there were no differences observed for manual therapy treatments.
In the few studies that reported on adverse events, these were mostly minor adverse effects of exercise, most commonly increased low back pain and muscle soreness, and the non-exercise groups also reported similar types and numbers of adverse effects. 

Toby: People might think that the evidence would be completely clear with 249 available trials but are there still gaps?

Jill: Most certainly. Although there is a lot of research in this field, there is a problem with quantity over quality. Our confidence in the evidence is limited due to lack of consistency in how the trials were done and the very small size of many of them, some with fewer than 10 participants per group. We think that researchers should stop doing these small trials and focus instead on larger, better designed studies, for example considering potential working mechanisms and cost-effectiveness of exercise compared to other treatments with similar effects. We also need implementation studies to understand how to increase compliance with the exercise programmes.

Toby: So, what is the next step for this review topic?

Jill:  I'm glad you asked… we're really excited about the next steps for this review. There have been no signs of slowing of trials being published on this topic - in addition to the 249 trials that we included, we also identified 172 recent studies and expect even more when we run an updated search in early 2022. This very large number of trials has led us to propose a new collaborative approach to evidence synthesis in which we will work collaboratively, and smarter, with several systematic review teams doing the update!

Toby: That sound very exciting and thanks again for speaking with me today, Jill. If people what to read the review and the future updates, where can they find it?

Jill:  Thanks Toby. Our review is online at Cochrane Library dot com. If people go to the website and type 'exercise for chronic low back pain' in the search box, they'll see it near the top of the list.