Maybe Chill With the Ibuprofen for Muscle Pain

Ultramarathons are hell on your body. That's why endurance runners and other hardcore exercisers are known for dosing themselves with "vitamin I"—the painkiller ibuprofen, that is. But a pair of recent studies support the idea that taking ibuprofen and other over-the-counter painkillers before exercise may seriously strain your kidneys and, ironically, lessen your muscles' ability to recover afterwards.

Ibuprofen blunts pain by suppressing inflammation; it's part of a popular group of painkillers known as nonsteroidal anti-inflammatory drugs, or NSAIDs. (Aspirin is also part of this group.) Athletes often use NSAIDs to push through demanding workouts, and even take them before or during competitions. The New York Times reports that, by some estimates, as many as 75 percent of long-distance runners use ibuprofen or other NSAIDs as part of their training regimen.

That doesn't mean they work. Recent studies have questioned whether taking NSAIDs before exercise actually helps performance; a study comparing pain and soreness reported by runners found no difference between those who used ibuprofen and those who didn't. But the notion persists that NSAIDs work as part of a "pain prevention" regimen, even while doctors say they should only be used to treat inflammation from acute injuries.

That's because besides offering no benefits, NSAIDs may do harm when combined with strenuous exercise. One new study, published Wednesday in the Emergency Medical Journal, looked at ultramarathoners: 89 of them were asked to take either an ibuprofen pill or a placebo every four hours over a 50-mile stretch of their race. Researchers then tested their levels of creatinine, a substance produced as the kidneys filter blood; high creatinine levels can indicate an acute kidney injury.

At the end of the 50-mile stage, about 44 percent of all participants showed creatinine levels high enough to suggest an acute kidney injury—that shows just how much stress ultramarathons put on even seasoned runners' bodies. But more importantly, the runners who'd taken ibuprofen were 18 percent more likely to have developed a kidney injury than those who took the placebo and their injuries tended to be more severe, based on their creatinine levels. Though the study didn't follow up with them, researchers believe the runners recovered normal kidney function.

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The study wasn't designed to answer why the ibuprofen-using runners saw an increased risk for kidney injuries, but the researchers think that it's exactly the drug's anti-inflammatory effects that may be to blame. Ibuprofen and other NSAIDs inhibit the body's production of prostaglandins, a group of biochemicals that respond to injury. Inhibiting them means less pain and inflammation, but it also means that blood vessels don't widen—that could mean less blood flow to the kidneys, forcing them to work hard to filter blood.

Besides making your kidneys work harder, blocking prostaglandins may also make it harder for your muscles to recover. In another recent study, researchers examined muscle cells and tissues from mice with the mouse equivalent of exercise-induced muscle damage. The injured areas filled with a type of prostaglandin that stimulated stems cells to start multiplying; they became muscle cells that repaired the damaged areas, making them stronger than before.

Researchers then used NSAIDs to block prostaglandin production in the muscles. That blunted the healing process: Fewer stem cells were activated, so fewer new muscle cells appeared. The tissue healed, but it wasn't as strong as similar tissues that had gotten their full dose of prostaglandins.

The implication for hard-exercising humans is that NSAIDs aren't helping you manage pain, and they may actually be temporarily impairing kidney function and impeding your body's healing process. Exercise strains the body, and inflammation and pain is part of getting back to normal as well as getting stronger. As Helen Blau, the director of the Baxter Laboratory for Stem Cell Biology at Stanford, who oversaw the mouse-tissue experiment, told the Times, when your body needs to rebuild, "it does look as if no pain means no gain."

The doctor in charge of the study on ultramarathoners suggested acetaminophen for pain, as the active ingredient in Tylenol works differently than NSAIDs. Another option: skipping the pills and dealing.

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