How does exercise training reduce pain?
We’re often told that exercise is good therapy for chronic pain. While evidence shows this to be true, a new study by IPAN researchers has revealed surprising findings about placebo treatments.
IPAN researchers Dr Clint Miller and Dr Patrick Owen, in collaboration with national and international colleagues, wanted to examine how effective exercise is to treat musculoskeletal pain conditions such as chronic back pain, Osteoarthritis and fibromyalgia.
The research team conducted a systematic review of the literature with a meta-analysis of 79 studies including 4719 patients.
Their findings, recently published in Sports Medicine journal, were surprising: exercise training improves chronic pain, but the effect is similar to that of a placebo treatment.
Chronic musculoskeletal conditions affect up to 20% of Australians. Pain is the most disabling characteristic of these conditions. Exercise therapy is strongly recommended as treatment for chronic musculoskeletal conditions. But the positive effect of exercise is not well understood – is it associated with a placebo effect or does pain naturally improve over time?
Dr Miller explained the placebo effect as where an improvement in symptoms is seen without a known effective treatment, such as when tablets without the active medication are given.
“The placebo effect is a fascinating phenomenon and occurs as part of all healthcare consultations,” he said.
“In clinical practice we refer to these as contextual factors. This is because positive or negative factors associated with the context of the clinical interaction can influence the outcomes – especially for subjective outcomes like pain.”
Dr Miller said outcomes such as pain can improve or worsen depending on the participant’s or clinician’s expectations of treatment effectiveness, or previous experience. It could even be moderated by learning of the experiences and outcomes of other people who have received treatment for the same condition.
“According to our findings, the effect of exercise training is the same as a placebo treatment. However, only four of the 79 studies we reviewed compared exercise to a placebo treatment – so the evidence base is not yet strong enough to make firm clinical recommendations,” Dr Miller said.
“It’s important to stress that evidence shows exercise therapy is effective – more effective than standard medical care for chronic musculoskeletal pain – but that more work is needed to understand how it works so that we can improve and optimise therapies to get the best possible outcomes for patients,” he said.
The research team continue to explore the relative effects of exercise treatment, placebo effects, and natural fluctuations in musculoskeletal pain conditions.
While the evidence in this study and the team’s previous work confirm that exercise is better than both no treatment and standard medical care, the decision about the most effective treatment for an individual is best discussed with a patient’s healthcare professional. In Australia, this means speaking with an Accredited Exercise Physiologist or Physiotherapist.
Dr Miller said future research should consider exercise therapy, placebo and a no treatment, or usual care in randomised controlled trials.
“This is the only possible way to assess how important each component is for reducing chronic musculoskeletal pain,” he said.
Miller CT, Owen PJ, Than C, Ball J, Sadler K, Piedimonte A, Benedetti F, Belavy DL (2021) Attempting to separate placebo effects from exercise in chronic pain: A systematic review and meta-analysis. Sports Medicine, doi: https://doi.org/10.1007/s40279-021-01526-6