Exercise therapy for chronic low back pain
Low back pain has been the leading cause of disability globally for at least the past three decades and results in enormous direct healthcare and lost productivity costs.
The primary objective of this systematic review is to assess the impact of exercise treatment on pain and functional limitations in adults with chronic non‐specific low back pain compared to no treatment, usual care, placebo and other conservative treatments.
We searched CENTRAL (which includes the Cochrane Back and Neck trials register), MEDLINE, Embase, CINAHL, PsycINFO, PEDro, SPORTDiscus, and trials registries (ClinicalTrials.gov and World Health Organization International Clinical Trials Registry Platform), and conducted citation searching of relevant systematic reviews to identify additional studies. The review includes data for trials identified in searches up to 27 April 2018. All eligible trials have been identified through searches to 7 December 2020, but have not yet been extracted; these trials will be integrated in the next update.
We included randomised controlled trials that assessed exercise treatment compared to no treatment, usual care, placebo or other conservative treatment on the outcomes of pain or functional limitations for a population of adult participants with chronic non‐specific low back pain of more than 12 weeks’ duration.
Data collection and analysis
Two authors screened and assessed studies independently, with consensus. We extracted outcome data using electronic databases; pain and functional limitations outcomes were re‐scaled to 0 to 100 points for meta‐analyses where 0 is no pain or functional limitations. We assessed risk of bias using the Cochrane risk of bias (RoB) tool and used GRADE to evaluate the overall certainty of the evidence. When required, we contacted study authors to obtain missing data. To interpret meta‐analysis results, we considered a 15‐point difference in pain and a 10‐point difference in functional limitations outcomes to be clinically important for the primary comparison of exercise versus no treatment, usual care or placebo.
We included 249 trials of exercise treatment, including studies conducted in Europe (122 studies), Asia (38 studies), North America (33 studies), and the Middle East (24 studies). Sixty‐one per cent of studies (151 trials) examined the effectiveness of two or more different types of exercise treatment, and 57% (142 trials) compared exercise treatment to a non‐exercise comparison treatment. Study participants had a mean age of 43.7 years and, on average, 59% of study populations were female. Most of the trials were judged to be at risk of bias, including 79% at risk of performance bias due to difficulty blinding exercise treatments.
We found moderate‐certainty evidence that exercise treatment is more effective for treatment of chronic low back pain compared to no treatment, usual care or placebo comparisons for pain outcomes at earliest follow‐up (MD ‐15.2, 95% CI ‐18.3 to ‐12.2), a clinically important difference. Certainty of evidence was downgraded mainly due to heterogeneity. For the same comparison, there was moderate‐certainty evidence for functional limitations outcomes (MD ‐6.8 (95% CI ‐8.3 to ‐5.3); this finding did not meet our prespecified threshold for minimal clinically important difference. Certainty of evidence was downgraded mainly due to some evidence of publication bias.
Compared to all other investigated conservative treatments, exercise treatment was found to have improved pain (MD ‐9.1, 95% CI ‐12.6 to ‐5.6) and functional limitations outcomes (MD ‐4.1, 95% CI ‐6.0 to ‐2.2). These effects did not meet our prespecified threshold for clinically important difference. Subgroup analysis of pain outcomes suggested that exercise treatment is probably more effective than education alone (MD ‐12.2, 95% CI ‐19.4 to ‐5.0) or non‐exercise physical therapy (MD ‐10.4, 95% CI ‐15.2 to ‐5.6), but with no differences observed for manual therapy (MD 1.0, 95% CI ‐3.1 to 5.1).
In studies that reported adverse effects (86 studies), one or more adverse effects were reported in 37 of 112 exercise groups (33%) and 12 of 42 comparison groups (29%). Twelve included studies reported measuring adverse effects in a systematic way, with a median of 0.14 (IQR 0.01 to 0.57) per participant in the exercise groups (mostly minor harms, e.g. muscle soreness), and 0.12 (IQR 0.02 to 0.32) in comparison groups.
We found moderate‐certainty evidence that exercise is probably effective for treatment of chronic low back pain compared to no treatment, usual care or placebo for pain. The observed treatment effect for the exercise compared to no treatment, usual care or placebo comparisons is small for functional limitations, not meeting our threshold for minimal clinically important difference. We also found exercise to have improved pain (low‐certainty evidence) and functional limitations outcomes (moderate‐certainty evidence) compared to other conservative treatments; however, these effects were small and not clinically important when considering all comparisons together. Subgroup analysis suggested that exercise treatment is probably more effective than advice or education alone, or electrotherapy, but with no differences observed for manual therapy treatments.
Jill A Hayden, Jenna Ellis, Rachel Ogilvie, Antti Malmivaara, Maurits W vanTulder
Plain language summary
Exercise for treatment of chronic low back pain
Is exercise an effective therapy to treat long‐lasting low back pain?
‐ Exercise probably reduces pain compared to no treatment, usual care or placebo in people with long‐lasting (chronic) low back pain.
‐ Exercise may reduce pain and improve disability compared to common treatments such as electrotherapy or education.
‐ There is a lot of research in this field but we need bigger and better designed studies to allow us to draw firm conclusions.
How might exercise help people with long‐lasting low back pain?
Long‐lasting (chronic) low back pain is a common cause of disability across the world and is expensive in terms of healthcare costs and lost working hours. Exercise therapy aims to increase muscle and joint strength, and improve muscle function and range of motion. This should reduce pain and disability, and speed recovery and return to usual activities. Exercise therapies are designed or prescribed by health professionals and cover a range of exercise types, durations, and delivery methods. Examples of exercise therapies include general physical fitness programmes delivered in a group setting, aerobic exercise in the form of walking programmes, and strengthening of specific muscles or groups of muscles to increase core stability.
What did we want to find out?
We wanted to know whether exercise improves pain and disability for people with chronic low back pain more than no treatment, usual care, placebo or other common treatments. In our review, chronic low back pain is pain that lasts three months or longer or that goes away but returns more than twice in one year. It does not have a specific cause such as a tumour or injury. Examples of common treatments are spinal manipulation, or psychological therapy. ‘Usual care’ is care provided by a family physician.
What did we do? -We searched for studies that assessed the effects of exercise therapy on pain or disability compared to no treatment, usual care, placebo or other common treatments. People in the studies had to be adults with chronic low back pain.
We compared and summarised the results of the studies and rated our confidence in the evidence, based on factors such as study methods and sizes.
What did we find?
We found 249 studies with a total of 24,486 people. Most studies took place in Europe (122 studies); other common study locations were Asia, North America, and the Middle East. Study participants’ average age was 43.7 years; 59% were women. Participants’ average pain intensity at the start of the studies was 51 points on a 100‐point scale, where 100 is the most pain. They had back pain for 12 weeks to 3 years (78 studies) or longer than 3 years (72 studies); 99 studies did not report how long their participants had low back pain.
Sixty‐one per cent of studies (151 studies) examined the effectiveness of two or more different types of exercise, and 57% (142 studies) compared exercise therapy to a non‐exercise treatment. The most common types of exercises were core strengthening (127 study groups), mixed exercises (>2 types) (109 study groups), Pilates (29 study groups), general strengthening exercises (52 study groups), and aerobic exercise (30 study groups). Exercise sessions were one‐on‐one with a healthcare provider (163 study groups) or in a group exercise class (162 study groups). More than half of studies included another treatment alongside exercise (247 study groups), including education or advice (137 study groups), electrotherapy (46 study groups), or manual therapy (21 study groups).
Most studies measured pain (223 studies) and disability (223 studies). Only 12 studies reported data that we could use on unwanted effects of treatments. Studies followed people in the short term (6 to 12 weeks; 184 studies); medium term (13 to 47 weeks; 121 studies) and long‐term (48 weeks or more, 69 studies).
We also identified 172 more recent studies that we will add to the next version of our review.
People receiving exercise therapy rated their pain on average 15 points better and their disability 7 points better, on a scale of 0 to 100, three months after the start of treatment compared to people who had no treatment, usual care or placebo. Exercise is probably more effective for pain (35 studies, 2746 people) and probably slightly more effective for disability (38 studies, 2942 people) than no treatment, usual care or placebo at all follow‐up periods.
Exercise may be more effective for pain (64 studies, 6295 people) and is probably more effective for disability (52 studies, 6004 people) than common treatments in the short and medium term.
Few studies reported mostly minor unwanted effects of exercise, most commonly increased low back pain and muscle soreness. However, the non‐exercise groups reported similar types and numbers of unwanted effects.
What are the limitations of the evidence?
Our confidence in the evidence is limited. The studies used exercise therapy in different ways and so reported different results from each other. Some studies were very small – the average number of participants was just 98. It is possible that the design of some studies may have made the benefits of exercise seem larger than they are.
How up to date is this evidence?
The evidence is up to date to 28 April 2018.
Jill A Hayden, Jenna Ellis, Rachel Ogilvie, Antti Malmivaara, Maurits W vanTulder
Implications for practice
Clinicians often turn to systematic reviews and the resulting guideline recommendations to inform their treatment of patients. This review fills an identified gap, the need for updated, high‐quality review of general exercise (Almeida 2020). We found moderate evidence that exercise probably provides a small benefit for pain outcomes in treatment of chronic low pain compared to no treatment comparisons (including usual care and placebo). The observed treatment effect for functional limitations outcomes was small and was not considered clinically important. Exercise treatment was found to have improved pain and functional limitations outcomes compared to other conservative treatments, however, these effects are small and not considered clinically important. We are not able to make recommendations about specific exercise types based on the results of this review, nor on the work of others to date; however, a related publication by this team will address this topic.
Due to insufficient reporting of adverse events in included trials, we are not able to confirm the safety or harms related to exercise treatment for chronic low back pain; however, the trials that did measure adverse events report few and mostly minor adverse effects, such as muscle pain. Based on available evidence, exercise is likely a good option to manage chronic low back pain. However, when determining if exercise is right for their patient, clinicians can take into consideration a wide range of factors including patient preference, suitability, access, and costs.
Implications for research
We have identified 451 RCTs on exercise treatment for chronic low back pain (279 assessed, 172 awaiting assessment). Low back pain researchers need to avoid further research waste by ensuring future trials contribute to the evidence base by thoughtful planning, robust conduct, large sample size, complete protocol and manuscript reporting, sharing trial data for validation and future meta‐syntheses, and publication to properly archive results.
One of the primary benefits of systematic review and meta‐analysis is combining studies of small sample sizes. However, the field is now saturated with small exercise trials many of which suffer from poor planning, conduct, and reporting due to limited resources. Efforts and research funding may be better spent on the co‐ordination of multi‐site studies, and the development of supports for good conduct and reporting.
It is our position that there needs to be more co‐ordinated and thoughtful planning of trials in the field. This includes the identification of existing gaps and the planning of exercise treatments and assessment of outcomes based on the proposed mechanisms of effect (Bird 2020; Wood 2020a).
Future trials should assess the recommended core outcome set (Chiarotto 2018), including health‐related quality of life and perceived effect; we found these important outcomes were only available for a small subset of studies. Trials should include the systematic measurement of harms, such as adverse events. There is also a need for careful selection of comparison groups to best contribute to evidence about the effective management of low back pain.
In addition, a more comprehensive measurement of baseline participant characteristics will allow for future investigation of treatment effect modifiers and mediating characteristics (even when single trials are insufficiently powered for such analyses). Currently, inconsistent availability and measurement of patient baseline characteristics limit the ability to assess the generalisability of the trials and the overall body of evidence. Furthermore, this limits the usefulness of the trial to contribute to future important IPD meta‐analyses. IPD meta‐analyses are the most feasible way to investigate potential treatment effect modifiers. Identifying potential treatment effect modifiers and the phenotypes of patients who are likely to benefit more from a specific treatment is an important goal and a long‐term back pain research priority (Costa 2009b; Henschke 2007).
We support and encourage initiatives to make research data accessible for testing and further analyses. There are several benefits of this, including opportunities to double‐check data (before, during or after publication), which provides a collegial way to ensure the best quality of evidence is disseminated. Data sharing has the additional benefit of enabling analyses of IPD data to identify treatment effect modifiers in a more robust way, without the limitations of ecological bias from study level data.
Finally, we believe there needs to be an increased emphasis on publishing trials in reputable journals with peer review and editorial processes to confirm the robustness of methods, assure complete reporting, and to require the proper archive of results to be included in future evidence reviews. If authors choose to publish their work in predatory journals, there does need to be a transparent system to determine if their trials should be eligible for inclusion in systematic reviews.
Future systematic review methods recommendations
One of the key benefits of a large overarching review, such as this one, is the ability to identify relationships that are not able to be investigated in smaller focussed reviews (e.g. characteristics of delivery, populations). Overarching reviews also have the potential to decrease the duplication of effort that often happens when multiple authors groups extract the same data for the same studies for inclusion in slightly different reviews. Overarching reviews enable the inclusion of trials that do not otherwise meet inclusion criteria for focussed reviews such as mixed exercise treatments (which represented 23% of all exercise groups in this review). However, feasibility of such large reviews is a barrier – they require tremendous time and resources for one team to complete and funding opportunities for systematic reviews are very limited. This presents an opportunity for more co‐ordination of efforts within the limits of the current flawed academic credit and funding system.
This review has highlighted additional methods considerations for future systematic reviews, including attention to issues of research integrity in RCTs. We need further study to understand how to appropriately define and measure problematic characteristics, and to understand the relationships between study integrity characteristics and the reported outcomes. Issues of poor conduct, incomplete reporting, insecure archiving, and outright fabrication or fraud cannot be ignored and may be more problematic in some fields. These issues are important for systematic review authors and warrant investigation and consideration in the selection of studies and in the analyses conducted to summarise a body of evidence.
We particularly draw attention to the issue of outlying and improbable results presented in RCTs. We defined a high threshold to consider results improbable or outlying and conducted sensitivity analyses to exclude these study data. In this review, the results and conclusions did not change in direction with the exclusion of improbable or outlying effects, adding robustness to the conclusions. However, the exclusion of these studies from analyses did impact the interpretation of the clinical importance of results; with a smaller number of studies, individual study results could have more weight in analyses and provide incorrect results and conclusions.
We posit that we should stop doing the same type of trials about exercise treatment. Additional trials are unlikely to add anything to our knowledge, unless they are based on a new and plausible hypothesis for the cause of low back pain and a potential working mechanism of the intervention. Future studies should evaluate whether exercise treatment is cost‐effective compared to other interventions with similar effects. This will help patients, clinicians and policy‐makers to decide which intervention to choose. Implementation studies that evaluate how to best introduce exercise treatment in healthcare settings, and how to increase compliance seem important as well. Additionally, using modern technologies to support exercise treatments, monitor compliance, give positive feedback, and monitor outcomes may be the best way forward.
Finally, progress in the field is unlikely to be feasible with small individual studies, so it will need to be facilitated by increased international collaboration, prospective planning of multi‐site and multi‐country trials, standardising measurement of baseline characteristics, and potentially by sharing of data through accessible repositories. Future prospective co‐ordination and collaboration for more consistent data collection will help researchers identify treatment effect modifiers. This will further advance a personalised management approach for chronic low back pain.