“Although the world is full of suffering, it is full also of the overcoming of it.” — Helen Keller
What is exercise?
Exercise is defined as “a subset of physical activity that is planned, structured, and repetitive and has as a final or an intermediate objective for the improvement or maintenance of physical fitness [1].”
In this article, we will focus on exercise as a rehabilitative tool to decrease acute and chronic pain.
Is exercise good for acute pain?
In short, no, but this comes with caveats.
Undoubtedly, exercise positively benefits most physiologic systems of the body [2]. With that being said, there is ample evidence that exercise for the treatment of acute pain is at worst inferior to, and at best equal to other forms of treatment [3-5].
Most of the evidence available is with regards to acute low back pain (LBP), and with good reason. LBP is one of the most common musculoskeletal conditions. It is one of the top 5 reasons a patient would visit a doctor, and one of the top 3 causes of disability.
Caveat #1: Some exercises are designed to unload the stress on pain-sensitive structures. For example, patients with sciatica caused by disc bulge or herniation may benefit significantly by performing movements in their spine’s directional preference (your doctor can would help you determine this during examination) [6]. These exercises may physically take pressure off of the nerves, decrease pain, and facilitate a faster recovery.
Caveat #2:
Though not technically exercise, staying physically active appears superior to bed rest, and at the least is not harmful. “It should be noted that exercise therapy and keeping active, the current recommended treatment for acute low-back pain, are not the same thing. Keeping active means moving around as much as possible within the limits of your pain and trying to be more active each day [7].”
Caveat #3:
Both cardiovascular and resistance training has been shown to produce ‘Exercise-induced Hypoalgesia’ (EIH) [8,9]. In studies, participants are exposed to a painful stimulus such as electrical stimulation, a high-temperature object, or a device that applies physical pressure, and are then asked to rate their pain levels. The participants then perform an exercise, repeat the procedure, and rate their pain levels again. Studies have repeatedly found that pain thresholds increase, or pain sensitivity decreases; however you want to look at it.
Unfortunately, the exercises need to be fairly intense to elicit this hypoalgesic response, which may not be feasible with an acute pain patient. On top of that, sensitivity to pain returns to baseline after about 30-50 minutes. The mechanism of EIH is not fully understood.
Is exercise good for chronic pain?
In short, yes, but this comes with a caveat as well.
“Increasing evidence purports exercise as a first-line therapeutic for the treatment of nearly all forms of chronic pain [10].”
Exercise has been shown to decrease pain in several chronic syndromes, including but not limited to osteoarthritis, complex regional pain syndrome, neck and back pain, knee pain, fibromyalgia, and headache [11,12].
“When applied to chronic pain conditions within appropriate parameters (frequency, duration, intensity), physical activity significantly improves pain and related symptoms [13].”
Additionally, exercise has also been well documented to improve psychological factors such as enhancing mood, decreasing anxiety and depression, and improving overall well-being, all factors associated with the chronic pain state [14].
Caveat #1:
There are a few conditions in which exercise may routinely increase pain: chronic fatigue syndrome, fibromyalgia, and chronic whiplash-associated disorders to name a few. These conditions exhibit dysfunctional endogenous analgesia [15]. In other words, their internal pain modulating system isn’t working properly. This doesn’t necessarily mean these individuals shouldn’t exercise altogether, just that they should start lower, take it slower, and allow more time for recovery compared to individuals without this dysfunction.
What kind of exercise is best?
For the general population that doesn’t suffer from chronic pain, you’ve got a broad brush to paint with when it comes to exercise selection. Staying close to the AHS/ACSM Physical Activity Guidelines is a good recommended start.
In chronic pain patients, the form of exercise that is most beneficial may depend on the chronic pain condition itself. For example; low back pain, neck pain, tension headache, and osteoarthritis respond positively to resistance exercise. In contrast, migraine headache and fibromyalgia sufferers respond more favorably to aerobic exercise.
Nonetheless, the beneficial effects of exercise will likely be optimized if it combines aerobic, resistance, and flexibility training.
“Exercise, in general, is therapeutic for a wide variety of chronic pain diagnoses, but it has been difficult to show that one particular approach is superior to another [16].”
“It may be that factors common to all exercises have the greatest mediating effect on pain and disability [17].”
How does exercise treat chronic pain?
The primary aim of exercise is to increase some measure of fitness, whether it is range of motion, strength, endurance, or some other aspect of physical function. One might reason that an improvement in one or more of these metrics is what decreases a person’s pain. Evidence is to the contrary.
“Research has also shown that specifically targeted exercise programs can improve chronic pain and function, but changes in pain do not correlate well with improvement in physical measures, suggesting that it may be something other than the change in musculoskeletal function that is mediating the pain relief [18].”
It is likely that the greatest effects of exercise on chronic pain take place in the brain, and not the musculoskeletal or cardiovascular systems. Pain modulation takes place in multiple areas of the brain, and through multiple mechanisms. These descending (top-down, from the brain to the body) pain modulatory systems use hormones and neurotransmitters to accomplish the task of pain reduction.
How exercise can reduce pain is being studied but has not been fully elucidated. Mechanistic studies have been and are currently being performed on the subject. More importantly, the empirical evidence is overwhelming at this point; physical exercise is a, if not the most, powerful tool for managing chronic pain.
Who can help?
Supervised and individually tailored exercise programs, especially those that take into account the physical limitations of the individual, have shown to be more beneficial than general exercise recommendations alone [19,20].
Exercise physiologists, recreational therapists, physical therapists, strength and conditioning coaches, and personal trainers, among other professionals, are well equipped to design and implement such programs. Any chronic pain patient not being referred to one of these specialists is woefully underserved.
Summary, Key Points:
Exercise doesn’t work well for acute pain.
Exercise is an excellent option for managing chronic pain.
The type of exercise that is best may depend on the type of chronic pain treated.
Exercise reduces pain regardless of physical improvements.
Glossary
Physiologic: a science that deals with the ways that living things function.
Hypoalgesia: Hypo (below, less than normal) algesia (sensitivity to pain).
Stimulus: something that causes something else to happen, develop, or become more active
Modulate: to change or adjust (something) so that it exists in a balanced or proper amount.
Resistance exercise: exercise that improves muscle strength and endurance.
Aerobic exercise: exercise that improves cardiorespiratory fitness.
Mechanistic study: A study or test designed to analyze the biologic or chemical events responsible for, or associated with, an effect observed, and to provide information concerning the molecular,cellular or physiological mechanisms by which substances exert their effects on living cells and organisms.
Empirical evidence: Empirical evidence is information that is acquired by observation or experimentation.
Works Cited
1. Blair, S, and D Jacobs. Physical Activity, Exercise, and Physical Fitness: Definitions and Distinctions for Health-Related Research. 1985.
2. Anderson, Elizabeth, and J. Larry Durstine. “Physical Activity, Exercise, and Chronic Diseases: A Brief Review.” Sports Medicine and Health Science, vol. 1, no. 1, Dec. 2019, pp. 3–10, 10.1016/j.smhs.2019.08.006. Accessed 7 Mar. 2022.
3. Chou, Roger, and Laurie Hoyt Huffman. “Nonpharmacologic Therapies for Acute and Chronic Low Back Pain: A Review of the Evidence for an American Pain Society/American College of Physicians Clinical Practice Guideline.” Annals of Internal Medicine, vol. 147, no. 7, 2 Oct. 2007, p. 492, 10.7326/0003-4819-147-7-200710020-00007. Accessed 8 Mar. 2022.
4. Van Tulder, Maurits, et al. “Exercise Therapy for Low Back Pain a Systematic Review within the Framework of the Cochrane Collaboration Back Review Group.” SPINE, vol. 25, no. 21, pp. 2784–2796. Accessed 8 Mar. 2022.
5. Park, Jung Yul. “Nonsurgical Management of Chronic Low Back Pain.” Journal of the Korean Medical Association, vol. 50, no. 6, 2007, p. 507, 10.5124/jkma.2007.50.6.507. Accessed 8 Mar. 2022.
6. Long, Audrey, et al. “Does It Matter Which Exercise?” Spine, vol. 29, no. 23, Dec. 2004, pp. 2593–2602, 10.1097/01.brs.0000146464.23007.2a.
7. https://www.iwh.on.ca/. Exercise Therapy and Low-Back Pain. 2007.
8. Koltyn, Kelli F. “Analgesia Following Exercise.” Sports Medicine, vol. 29, no. 2, 2000, pp. 85–98, 10.2165/00007256-200029020-00002. Accessed 11 Mar. 2022.
9. Lee, Han Suk. “The Effects of Aerobic Exercise and Strengthening Exercise on Pain Pressure Thresholds.” Journal of Physical Therapy Science, vol. 26, no. 7, 2014, pp. 1107–1111, 10.1589/jpts.26.1107. Accessed 17 Mar. 2022.
10. Polaski, Anna M., et al. “Exercise-Induced Hypoalgesia: A Meta-Analysis of Exercise Dosing for the Treatment of Chronic Pain.” PLOS ONE, vol. 14, no. 1, 9 Jan. 2019, p. e0210418, 10.1371/journal.pone.0210418. Accessed 9 Mar. 2022.
11. Kroll, Heather R. “Exercise Therapy for Chronic Pain.” Physical Medicine and
Rehabilitation Clinics of North America, vol. 26, no. 2, May 2015, pp. 263–281, 10.1016/j.pmr.2014.12.007. Accessed 15 Mar. 2022.
12. Daenen, Liesbeth, et al. “Exercise, Not to Exercise, or How to Exercise in Patients with Chronic Pain? Applying Science to Practice.” The Clinical Journal of Pain, vol. 31, no. 2, Feb. 2015, pp. 108–114, 10.1097/ajp.0000000000000099. Accessed 17 Mar. 2022.
13. Ambrose, Kirsten R., and Yvonne M. Golightly. “Physical Exercise as Non-Pharmacological Treatment of Chronic Pain: Why and When.” Best Practice & Research Clinical Rheumatology, vol. 29, no. 1, Feb. 2015, pp. 120–130, 10.1016/j.berh.2015.04.022. Accessed 22 Mar. 2022.
14. Hassmén, Peter, et al. “Physical Exercise and Psychological Well-Being: A Population Study in Finland.” Preventive Medicine, vol. 30, no. 1, Jan. 2000, pp. 17–25, 10.1006/pmed.1999.0597. Accessed 17 Mar. 2022.
15. Daenen, Liesbeth, et al. “Exercise, Not to Exercise, or How to Exercise in Patients with Chronic Pain? Applying Science to Practice.” The Clinical Journal of Pain, vol. 31, no. 2, Feb. 2015, pp. 108–114, 10.1097/ajp.0000000000000099. Accessed 17 Mar. 2022.
16. Kroll, Heather R. “Exercise Therapy for Chronic Pain.” Physical Medicine and Rehabilitation Clinics of North America, vol. 26, no. 2, May 2015, pp. 263–281, 10.1016/j.pmr.2014.12.007. Accessed 22 Mar. 2022.
17. Smith, Benjamin E, et al. “Musculoskeletal Pain and Exercise—Challenging Existing Paradigms and Introducing New.” British Journal of Sports Medicine, vol. 53, no. 14, 20 June 2018, pp. 907–912, 10.1136/bjsports-2017-098983. Accessed 15 Mar. 2022.
18. Kroll, Heather R. “Exercise Therapy for Chronic Pain.” Physical Medicine and Rehabilitation Clinics of North America, vol. 26, no. 2, May 2015, pp. 263–281, 10.1016/j.pmr.2014.12.007. Accessed 17 Mar. 2022.
19. Hayden, Jill, et al. “Exercise Therapy for Treatment of Non-Specific Low Back Pain.” Cochrane Database of Systematic Reviews, 20 July 2005, www.cochrane.org/CD000335/BACK_exercise-therapy-for-treatment-of-non-specific-low-back-pain, 10.1002/14651858.cd000335.pub2. Accessed 15 Apr. 2019.
20. Ambrose, Kirsten R., and Yvonne M. Golightly. “Physical Exercise as Non-Pharmacological Treatment of Chronic Pain: Why and When.” Best Practice & Research Clinical Rheumatology, vol. 29, no. 1, Feb. 2015, pp. 120–130, 10.1016/j.berh.2015.04.022. Accessed 17 Mar. 2022.
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