Exercise Induced Hypoalgesia
Exercise is an important component of effective chronic pain management and has a number of potential benefits. Long term exercise training has been shown to relieve pain, across many chronic pain conditions. However, the response is often variable and exercise induced flares in pain are common. Exercise typically leads to an acute reduction in pain and pain sensitivity for up to 30 minutes afterwards. This is called exercise induced hypoalgesia (EIH).
Typically we see reduced pain sensitivity both close to the exercising muscle (local EIH), and remote sites, away from the exercising muscle (global/remote). Local EIH is greater than Global/Remote EIH.
In pain free adults, the dose response for aerobic Exercise is moderate to high intensity, achieving 65-70% or more of max heart rate. Longer durations better. With resistance Exercise, both isometric and dynamic (isotonic) exercise can achieve an effect. High intensity resistance exercise should be 60-100% 1RM. Low intensity should be 10-30% 1RM with a sufficiency duration of contraction (> 3 mins or to failure).
EIH is variable in those with chronic pain. Rice et al reviewed the evidence and found EIH was generally significantly impaired in chronic pain populations on at least one measure in most studies. The populations were EIH was impaired was in chronic widespread pain, fibromyalgia, whiplash, localised myalgia, chronic neck pain, osteoarthritis, diabetic neuropathy. Normal EIH was achieved in some studies in rheumatoid arthritis, chronic back pain, and osteoarthritis.
Resources
- Rice et al review paper 2019[1]
