DAVID GREENE, HOST:
For those of you living with chronic pain, getting up and moving around could be the last thing you feel like doing because physical activity is just going to make the pain worse, right? Well, researchers now say the opposite is true. Exercise can help reduce the pain. Here's NPR's Patti Neighmond.
PATTI NEIGHMOND, BYLINE: Emma Dean (ph) is 44 years old. And until recently, she pretty much avoided exercise. Just climbing stairs was painful.
EMMA DEAN: Sometimes to the point where I would have to hold onto the banister to help and couldn't even extend my leg. It almost feels like a tearing of the ligaments in the knee, and that's what causes the pain.
NEIGHMOND: Dean was diagnosed at a fairly young age with osteoarthritis in both knees. Lucky for her, she says, she worked at the Thurston Arthritis Research Center at the University of North Carolina. The woman in the cubicle next to hers ran a program that encouraged people with osteoarthritis to get out and start walking to help reduce their pain. Dean was skeptical but agreed to give it a try.
DEAN: I felt stiff. And I felt tired, out of breath. But after a few days - I mean, literally, after a few days, I started to feel looser in my joints. I wasn't as out of breath, and my mood started to improve.
NEIGHMOND: Today, she walks about 40 minutes, five times a week. She feels great - out in nature, breathing fresh air, talking to neighbors. And her knee...
DEAN: My knee feels like it did when I was young. It doesn't hurt me anymore.
NEIGHMOND: So how does this happen? It's partly mechanical. Exercise builds muscle strength, reduces joint stiffness and inflammation. All help reduce pain. But neuroscientist Benedict Kolber with Duquesne University in Pittsburgh says exercise can also cause changes in the brain.
BENEDICT KOLBER: Exercise engages your, what we call, endogenous opioid system. So our bodies make opioids, and we use these opioids, or your body uses these opioids, to decrease pain.
NEIGHMOND: These natural opioids bind to the same receptors in the brain as narcotics but without the complications or potential for addiction.
KOLBER: There are some circumstances, like a runner's high, in which your body can produce so much of these natural opioids that you actually get some sense of euphoria or, as we call it, runner's high.
NEIGHMOND: And he says exercise also seems to activate parts of the brain that are involved in decreasing pain.
KOLBER: It's these parts of your brain that seem to be activated in exercise, and that then turns down the pain system.
NEIGHMOND: And Kolber says exercise also seems to decrease stress, and stress can make people more sensitive to pain. Now, Emma Dean's initial hesitancy to start walking is pretty typical, says exercise physiologist Kirsten Ambrose, with the University of North Carolina.
KIRSTEN AMBROSE: Chronic pain is debilitating, and a lot of people don't want to be physically active because they're afraid it will make their pain worse.
NEIGHMOND: Ambrose heads the Osteoarthritis Action Alliance at UNC, which promotes walking programs.
AMBROSE: Everybody knows how to walk. It's inexpensive. You need a pair of shoes and a safe location, and off you go.
NEIGHMOND: And she says most people who try it react like Emma Dean. After exercising routinely for a while, their pain diminishes. Neuroscientist Kolber wanted to know if the amount of exercise makes a difference. Can people reduce their pain even more by increasing the amount of time they exercise?
KOLBER: Anyone develops any drug, they have to go through hundreds of different tests and trials looking at dose. But in exercise, there's almost no data, especially in the context of pain.
NEIGHMOND: Kolber did a study measuring people's sensitivity to pain before and after exercise using heat and pressure. Healthy individuals walked briskly on a treadmill for 30 minutes. Some exercised three times a week. Others, five or 10 times. And while there was no difference in pain perception after exercise for those who walked three times a week, it was a whole different story for the people who exercised five times or more.
KOLBER: At the end of the study, they rated the same pressure as 60% less painful than they did at the beginning.
NEIGHMOND: So if you're going to try this, don't just do it once or twice a week. To get the most benefit, Kolber says, shoot for exercising at least five times a week or more.
Patti Neighmond, NPR News. Transcript provided by NPR, Copyright NPR.