Exercise Presents Double-Edged Sword in Addressing Opioid Addiction

In Brief


What’s the current best way to treat patients addicted to painkillers? You might be surprised to learn the answer is exercise. Scientists are finding out that exercise may be of benefit when it comes to decreasing opioid addiction. Opioids are pain-relieving drugs that doctors can prescribe when patients are in severe pain due to surgery, illness, or injury. They are very addictive however, meaning some patients end up relying on these drugs even after their physical pain has passed. It’s very risky for patients to take more opioids than needed because they may become increasingly tolerant. This means the effects of a drug are decreased after prolonged use, so patients need to take more of the medication in order to obtain the same effect.

Where does exercise come in? Dr. Mark Smith of Davidson College studies addiction and the behavioral effects of opioids and cocaine. He says studies have shown “there is no medication out there that reduces drug intake as much as exercise.”

The journal of Pathophysiology published a study showing Wistar rats exercising for 11 days prior to jugular surgery self-administer less morphine (using a lever) than rats that never exercise at all. “Exercise does reliably reduce drug intake including the intake of heroin and other opioids… as long as the individual continues to exercise,” Dr. Smith explains.

Clinical studies in humans already addicted to other drugs have shown similar results. In these studies, Dr. Smith says people who exercise “report big decreases in craving” compared to a control group of patients who do not exercise. However, Dr. Smith warns, once the study is over, patients go one of two ways. He says those who “continue to exercise after treatment do beautifully. They run a very low risk of relapse.” But patients who stop exercising don’t see considerable progress.

The impact of exercise on opioid use isn’t entirely clear cut however. In another research study, Dr. Smith found rats that frequently exercise are exposed to endogenous opioids released by the brain. Morphine and other opioids have a similar makeup to these endogenous chemicals, so a person may become tolerant to morphine and other opioids in response to frequent exercise. 

Some scientists speculate tolerance from exercise may mean human athletes require higher doses of opioids. However, studies in rats should be viewed with caution, particularly when previous findings have shown conflicting results. Nevertheless, the exciting avenue of research into the impacts of exercise on opioid use has the potential for assisting patients in their recovery from addiction and helping athletes understand the natural pain-relief process that occurs when they exercise.

Content Experts

Dr. Mark Smith, Ph.D., is a professor of psychology at Davidson College in North Carolina. Dr. Smith is an expert in addiction, and his research investigates the behavioral impacts of opioids and cocaine. He focuses on variables that influence drug sensitivity in individuals.

Works Cited

  1. Shokraviyan, M., Miladi-Gorji, H., & Vaezi, G. H. (2014). Voluntary and forced exercises prevent the development of tolerance to analgesic effects of morphine in rats. Iranian Journal of Basic Medical Sciences, 17(4), 271–277.
  2. Smith, M.A. & Yancey, D.L. (2003). Sensitivity to the effects of opioids in rats with free access to exercise wheels: Mu opioid tolerance and physical dependence. Psychopharmacology, 167, 426-434. doi:10.1007/s00213-003-1471-5
  3. De Coverley Veale, D. M. (1987). Exercise Dependence. British Journal of Addiction, 82(7), 735-740. doi:10.1111/j.1360-0443.1987.tb01539.x
  4. Hosseini, M., Alaei, H. A., Naderi, A., Sharifi, M. R., & Zahed, R. (2009). Treadmill exercise reduces self-administration of morphine in male rats. Pathophysiology, 16(1), 3–7. doi:10.1016/j.pathophys.2008.11.001


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This article was written by Celeste Basken. Celeste and the cSw student editing team would like to thank Donald Schwartz for serving as a mentor on this story. Donald Schwartz is executive director of Merial’s US Business Operations.

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