Exercise and Activity in Pain Management

Introduction[edit | edit source]

The International Association for Study of Pain (IASP) defines pain as: "An unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage."[1] It further states that: "Pain is always subjective. Each individual learns the application of the word through experiences related to injury in early life."[1] IASP also argues that "[a]ctivity induced in the nociceptor and nociceptive pathways by a noxious stimulus is not pain".[1]

For people experiencing pain, their initial response may be to avoid activity and seek rest. However, exercise therapy can be an important treatment for pain. There are many other additional benefits of exercise and regular physical activity, including:[2]

  • Controls weight
  • Reduces risk of cardiovascular disease and metabolic disease
  • Reduces risk of some cancers
  • Strengthens bones and muscles
  • Improves mental health and mood
  • Improves ability to perform daily activities and prevent falls
  • Increases chances of living longer

Exercise and physical activity not only have benefits for healthy individuals - they also have proven benefits in various patient populations.[3][4][5] Because of this, some authors have explored the idea that exercise acts as a drug.[6]

Exercise Induced Hypoalgesia (EIH)[edit | edit source]

Exercise induced hypoalgesia (EIH) is phenomenon which has been extensively studied in the literature, but the mechanisms behind EIH are not fully understood.[7] EIH is characterised "by elevations in pain threshold and tolerance as well as reductions in pain intensity ratings during and following exercise."[8]

"The most commonly tested hypothesis for EIH is that exercise induces a release of endogenous opioids at either peripheral, spinal, and/or central sites: all of which contribute to pain modulation."[8] Koltyn et al.[8] note the following about the endogenous opioid mechanism:

  • Muscle contractions activate A-delta and C fibres in skeletal muscle, the stimulation of which can lead to the activation of the endogenous opioid system
  • Exercise can increase blood beta-endorphin contractions in males
  • Peripheral afferent neuron stimulation might modulate pain by activating spinal / supraspinal inhibitory mechanisms

It is important to note, however, that early research in EIH and the opioid mechanism focused on pain-free adults/animals and the research on humans is "equivocal".[7] There are also examples of "EIH that is insensitive to opioid antagonists".[7]

  • The endocannabinoid system[7][8] - it is argued that exercise increases serum concentrations of endocannabinoids which may contribute to control of pain transmission. There may also be an association between the endocannabinoid and opioid systems where the activation of one system is mediated by the other.[7]
  • Animal experiments suggest that there may be an interaction between opioid and serotonergic mechanisms to cause EIH[7]

Other theories behind EIH are discussed in detail in Exercise-induced hypoalgesia in pain-free and chronic pain populations: state of the art and future directions.

Effects of Different Types of Exercise in Pain Management[edit | edit source]

Pain control is achieved differently with different types of exercises. Prescribing appropriate intensity and frequency of exercise is important in achieving the desired effects of hypoalgesia. However, it has been found that many physiotherapists "lack knowledge and training to provide physical activity advice, and to prescribe aerobic exercise and resistance training to people with musculoskeletal pain."[9] The following sections provide some information on different types of exercise for pain management.

Aerobic Exercise/Endurance Training[edit | edit source]

The effects of aerobic exercises on pain have been extensively studied in the literature. The intensity of the exercise should be well tolerated for the exercise to be effective. It is argued that aerobic exercise should target larger muscle groups, involve repetitive muscle contraction and elevate the resting heart rate to the target heart rate for at least 20 minutes.[10] The therapeutic window for aerobic training is extremely important, as some individuals may exhibit worsening of symptoms secondary to exercise. Musculoskeletal pain is one of the side effects of exercise, thus achieving the right balance is very important. Too little exercise is not beneficial, but too much exercise can aggravate symptoms.

Various prescribed workloads have been suggested to result in EIH:

  • Hoffman et al.[10] found that 30 minutes of treadmill exercise at 75% of VO2max resulted in a significant decrease in pain ratings. However, they found that there were no significant changes with 10 minutes of treadmill exercise at 75% VO2max or 30 minutes at 50% VO2max.
  • A review by Koltyn[11] found that hypoalgesia consistently occurs after high-intensity exercise, particularly with workloads of 200 W and higher. It also occurs with exercise at prescribed at 65 to 75% of VO2max. Koltyn[11] notes that results were not conclusive when percentage of a heart rate maximum was used a prescribing criteria or when subjects were allowed to select their own exercise intensity.

Resistance Exercise/Strength Training[edit | edit source]

In 1998, Koltyn and Arbogast[12] found that a single bout of resistance exercise resulted in a hypoalgesic response from resistance training. The exercise session lasted 45 minutes. Exercises included the bench press, leg press, pull downs and arm extensions. The following parameters were used: 3 sets of 10 repetitions at 75% of 1 repetition maximum.[12]

While EIH has a proposed central mechanism, it has also been found that the EIH response is greater in the exercising body part than non-exercising body parts.[13] Vaegter et al.[13] asked participants to perform two isometric contractions of their dominant biceps brachii and quadriceps at 30% and 60% maximum voluntary contraction. They found that high intensity isometric contraction of these muscles had a larger local EIH effect than low intensity contraction.

Condition Specific Information[edit | edit source]

Therapeutic exercises are the primary non-pharmacological treatment for chronic neck pain, chronic low back pain, complex regional pain syndrome, fibromyalgia, osteoarthritis and similar other unremitting pain syndromes.[14][15]

O'Leary et al.[16] report an immediate local mechanical hypoaglesic response with specific cervical spine exercises in individuals who have had neck pain for at least 3 months. The exercises included were (1) cranio-cervical flexion with a 10 second contraction for 10 repetitions with 10 second hold in between, and (2) cervical flexion endurance exercise of head lift in supine for 3 sets of 10 repetitions at 12 repetition maximum with a 30 second rest in between sets (each repetition lasted for 3 seconds with a 2 second interval between repetitions).[16]

A systemic review by Hayden et al.[17] concluded that supervised exercise therapy which consists of stretching and strengthening, and which is individually designed, improves pain and function in chronic non-specific back pain.

Martin et al.[18] designed an exercise programme which has shown to be an effective management for fibromyalgia in short term. This exercise programme included aerobic training, flexibility exercises and strength training.

Adverse Effects of Exercise[edit | edit source]

If exercise is considered a drug, like another other drug, there may be adverse effects.

It is typically accepted that exercise results in myofiber damage, and substances like lactate are released which provide nociceptive input in response to exercise. Thus, there is a risk of a flare up of symptoms after exercise. Exercise is considered a physical stressor and it has been known to activate the stress responses in the neuroendocrine system. Hence, clinicians should be careful when prescribing exercises to individuals with pain.[8] Applying physical stress in small amounts with an adequate rest-recovery period may be optimal, while excessive stress may increase pain sensitivity.[19]

Physical Activity[edit | edit source]

Bed rest and immobility for more than two days are known to have detrimental effects.[10] Physical activities like Tai Chi and Yoga can result in significant improvements in pain control/prevention. The ancient practice of Tai Chi appears to be an effective intervention for osteoarthritis, low back pain and fibromyalgia.[12] Yoga, which has been practised since 500-200 BCE, is considered an effective adjunctive treatment for chronic low back pain.[16] Regular physical activity helps prevent joint stiffness, muscle tightness and improves blood circulation. Other physical activities like swimming and walking can also be effective in decreasing pain and improving function. A study by Ickmans et al.[20] highlights the important role that rehabilitation programmes can have in the long-term management of people with chronic pain.

Conclusion[edit | edit source]

When prescribing exercise for pain management it is important that we:

  1. Understand the parameters (i.e., mode, frequency, duration, intensity) of therapeutic exercise for pain relief.
  2. Describe how to modify exercise parameters as they relate to the pain condition, age, psychosocial factors, and an individual's health status.
  3. Recognise the importance of implementing adjunct therapies to address issues related to exercise prescription (i.e., biopsychosocial, fear avoidance behaviour, catastrophising, cognitive behavioural therapy).
  4. Understand the importance of patient education in prescribing therapeutic exercise, including the concept of motivation, pacing) to enhance overall treatment effectiveness and compliance.

References[edit | edit source]

  1. 1.0 1.1 1.2 International Association for the Study of Pain (IASP). Making a definition of pain work for us. Available from: https://www.iasp-pain.org/publications/relief-news/article/definition-pain/ (accessed 17 January 2023).
  2. Centers for Disease Control and Prevention (CDC). Benefits of Physical Activity. Available from https://www.cdc.gov/physicalactivity/basics/pa-health/index.htm (accessed 17 January 2023).
  3. D'Ascenzi F, Anselmi F, Fiorentini C, Mannucci R, Bonifazi M, Mondillo S. The benefits of exercise in cancer patients and the criteria for exercise prescription in cardio-oncology. Eur J Prev Cardiol. 2019 Oct 6:2047487319874900.
  4. Kim Y, Lai B, Mehta T, Thirumalai M, Padalabalanarayanan S, Rimmer JH, Motl RW. Exercise training guidelines for multiple sclerosis, stroke, and Parkinson disease: rapid review and synthesis. Am J Phys Med Rehabil. 2019 Jul;98(7):613-21.
  5. Maestroni L, Read P, Bishop C, Papadopoulos K, Suchomel TJ, Comfort P, Turner A. The benefits of strength training on musculoskeletal system health: practical applications for interdisciplinary care. Sports Med. 2020 Aug;50(8):1431-50.
  6. Vina J, Sanchis‐Gomar F, Martinez‐Bello V, Gomez‐Cabrera MC. Exercise acts as a drug; the pharmacological benefits of exercise. British journal of pharmacology. 2012 Sep 1;167(1):1-2.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 Rice D, Nijs J, Kosek E, Wideman T, Hasenbring MI, Koltyn K, et al. Exercise-induced hypoalgesia in pain-free and chronic pain populations: state of the art and future directions. J Pain. 2019 Nov;20(11):1249-66.
  8. 8.0 8.1 8.2 8.3 8.4 Koltyn KF, Brellenthin AG, Cook DB, Sehgal N, Hillard C. Mechanisms of exercise-induced hypoalgesia. The Journal of Pain. 2014 Dec 31;15(12):1294-304.
  9. Barton CJ, King MG, Dascombe B, Taylor NF, de Oliveira Silva D, Holden S, Goff AJ, Takarangi K, Shields N. Many physiotherapists lack preparedness to prescribe physical activity and exercise to people with musculoskeletal pain: a multi-national survey. Physical Therapy in Sport. 2021 May 1;49:98-105.
  10. 10.0 10.1 10.2 Gloth MJ & Matesi AM. Physical therapy and exercise in pain management. Clinics in Geriatric Medicine. 2001. 17(3): 525-535.
  11. 11.0 11.1 Koltyn KF. Exercise-induced hypoalgesia and intensity of exercise. Sports Med. 2002;32(8):477-87.
  12. 12.0 12.1 12.2 Koltyn KF, Arbogast RW. Perception of pain after resistance exercise. British journal of sports medicine. 1998 Mar 1;32(1):20-4.
  13. 13.0 13.1 Vaegter HB, Handberg G, Graven-Nielsen T. Similarities between exercise-induced hypoalgesia and conditioned pain modulation in humans. PAIN®. 2014 Jan 31;155(1):158-67.
  14. Zampogna B, Papalia R, Papalia GF, Campi S, Vasta S, Vorini F, Fossati C, Torre G, Denaro V. The role of physical activity as conservative treatment for hip and knee osteoarthritis in older people: a systematic review and meta-analysis. Journal of clinical medicine. 2020 Apr 18;9(4):1167.
  15. Skou ST, Roos EM. Physical therapy for patients with knee and hip osteoarthritis: supervised, active treatment is current best practice. Clin Exp Rheumatol. 2019 Sep 1;37(suppl 120):112-7.
  16. 16.0 16.1 16.2 O’Leary S, Falla D, Hodges PW, Jull G, Vicenzino B. Specific therapeutic exercise of the neck induces immediate local hypoalgesia. The Journal of Pain. 2007 Nov 30;8(11):832-9.
  17. Thorén P, Floras JS, Hoffmann P, Seals DR. Endorphins and exercise: physiological mechanisms and clinical implications. Medicine & science in sports & exercise. 1990 Aug. 22(4): 417-428
  18. Koltyn KF, Brellenthin AG, Cook DB, Sehgal N, Hillard C. Mechanisms of exercise-induced hypoalgesia. The Journal of Pain. 2014 Dec 31;15(12):1294-304.
  19. Niemeijer A, Lund H, Stafne SN, Ipsen T, Goldschmidt CL, Jørgensen CT, Juhl CB. Adverse events of exercise therapy in randomised controlled trials: a systematic review and meta-analysis. British journal of sports medicine. 2020 Sep 1;54(18):1073-80.
  20. Ickmans K, Voogt L, Nijs J. Rehabilitation Succeeds Where Technology and Pharmacology Failed: Effective Treatment of Persistent Pain across the Lifespan. J Clin Med. 2019 Nov 21;8(12):2042.