33 Possible Ways Exercise Relieves Chronic Low Back Pain

Source: Mohamed Hassan/Pixabay

Even though exercise is regularly prescribed for the management of chronic low back pain (CLBP), a new review of 110 research papers was unable to pinpoint exactly why fitness training alleviates CLBP. As the title of a Dec. 17 news release from the University of New South Wales in Australia sums up: "Exercise for Low Back Pain Is Beneficial, but No One Agrees on Why."

This systematic review (Wun et al., 2020) led by James McAuley and senior author Matt Jones was recently published in Musculoskeletal Science and Practice. Annika Wun of UNSW Medicine is the paper's first author. All told, the 110 clinical studies included in this review spanned decades (1989-2019) and involved thousands of participants with CLPB from different countries around the globe.

"Exercise is one non-pharmacological intervention commonly used to manage CLBP. Exercise also provides modest improvements in pain and function for people with CLBP and is cost-effective. Consequently, exercise is recommended for CLBP by most clinical guidelines, with no clear recommendation for one type of exercise over another," the authors explain.

"This broad recommendation probably reflects uncertainty about the mechanism(s) through which exercise exerts positive effects on pain and function," they add.

"[We] were surprised to find there was no clear agreement between scientists about why they think exercise works for CLBP," Jones stated in the news release. "Therefore, despite decades of research in the area and more than 100 studies we analyzed in our review, we still do not have a good idea of why exercise might be effective for CLBP."

That being said, the researchers did identify 33 unique mechanisms—grouped into five themes (neuromuscular, psychosocial, neurophysiological, cardiometabolic, tissue healing)—that, taken together, lay out a wide range of factors that may work in various combinations to alleviate low back pain via exercise.

For each of these five themes, Wun et al. provide text samples from the various studies in their review that support why a proposed mechanism may help people with chronic low back pain. Here are some examples from their paper:

1. Neuromuscular: "Effective in decreasing the incidence and duration of low back pain episodes by improving strength and endurance of trunk muscles, by increasing flexibility of soft tissue, by correcting postural alignment."
2. Psychosocial: "Reductions in fear, avoidance, anxiety, emotional distress, and perceived pain and disability and self-efficacy."
3. Neurophysiological: "By influencing the dysfunctional descending pain inhibitory mechanism" and "the release of pain-relieving neuropeptides (endorphin and serotonin)."
4. Cardiometabolic: "Improvement in the aerobic capacity is clinically and statistically correlated to a decrease in the pain."
5. Tissue Healing: "Blood flow and nutrients which accelerate the healing process and reduce stiffness that results in back pain."

33 Unique Mechanisms May Explain Why Exercise Works for CLBP

Here's a summary (Table 2) of 33 ways exercise may work for low back pain ranked in descending order (based on how many times each mechanism was proposed) in the 110 studies analyzed for this review:

1. Muscle strength (30)
2. Motor control (21)
3. Muscle endurance (18)
4. Fear-avoidance (15)
5. Pain self-efficacy (14)
6. Mood (12)
7. Flexibility (11)
8. Endorphins (11)
9. Kinesiophobia (10)
10. Aerobic fitness (9)
11. Stabilization (9)
12. Pain tolerance (8)
13. Disability perception (7)
14. Mastery (6)
15. Biomechanics (6)
16. Blood flow (6)
17. Social support (5)
18. Proprioception (5)
19. Catastrophizing (4)
20. Body composition (4)
21. Descending inhibition (4)
22. Stress response (4)
23. Inflammation (3)
24. Gate control (3)
25. Coping strategies (3)
26. Muscle tension (2)
27. Postural alignment (2)
28. Body weight (2)
29. Bone/ligament (2)
30. Mindfulness (1)
31. Muscle power (1)
32. Tissue restoration (1)
33. Sleep (1)

"[CLBP] is the kind of pain that extends beyond the expected healing time of the body tissue. We also know that for many people, it is part of their daily lives and can significantly impact their quality of life," Jones said in the news release. "A lot of treatments have stemmed from studies for people with CLBP (for example, medications, manual therapy, cognitive behavioral therapy), but the one with the most consistent evidence of benefit is exercise."

"Future primary studies could involve randomized controlled trials designed to investigate the mechanisms of benefit identified in our review," James McAuley of Neuroscience Research Australia and NeuRA's Centre for Pain IMPACT concluded. "If we can identify why exercise works, then we can design treatments to maximize its benefits. Pain is very complex—so, in all likelihood, it will be a combination of many factors that lead to consistent improvements in pain and function after exercise for people with CLBP."