Statins, common cholesterol-lowering medications, may actually counteract certain benefits of exercising, according to a new study.

Statins undoubtedly help people with high cholesterol and a family history of heart disease, the study's lead author warns.

"There's no doubt that statins save lives," John P. Thyfault, senior author of the study, and professor of nutrition and exercise physiology at the University of Missouri, told the New York Times.

But the study's findings, published online in The Journal of the American College of Cardiology, present a dilemma for doctors and patients.

Sedentary, overweight people who stand to benefit considerably from exercise are the most likely to be put on statins. Those drugs could have life-saving effects, including reducing the risk of heart disease.

However, researchers found that among their overweight test subjects, those who did not take the medications saw significantly better results than those who did.

After three months, aerobic fitness increased by more than 10 percent for those not taking statins. For those taking statins, aerobic fitness increased barely 1 percent, and some patients taking statins were worse-off than when they started.

The study, performed by researchers at the University of Missouri and other institutions, looked at subjects with elevated but not dangerously elevated cholesterol. The men and women who participated in the study had multiple symptoms of metabolic problems, including wide waistlines, high blood pressure, and excess abdominal fat.

None had exercised regularly during the past year.

The participants underwent a 12-week exercise program. Five times per week, they visited the university lab and walked or jogged on a treadmill for 45 minutes, at a moderately vigorous pace (65 to 70 percent of individual aerobic maximum).

Half the group began taking a statin, simvastatin, sold under the brand name Zocor. The daily dose was 40 milligrams.

The health of participants was tested at the beginning and end of the study, via muscle biopsy and treadmill testing.

Common sense suggests that patients taking statins would do better, because the cholesterol-fighting benefits of statins are well-documented.

However, researchers discovered the surprising result that patients who took statins fared worse.

This is the first study that examined the effects of statins in people who exercise.

The reason for the discrepancy between statin users and those who exercised without the use of statins was not immediately clear. After investigating, however, the researchers determined that an enzyme related to the health of mitochondria was being affected by the statins.

Mitochondria are organelles that produce ATP, the energy currency of the cell. ATP is consumed at an especially high rate during vigorous activities, such as jogging on a treadmill.

By the end of the experiment, for participants taking statins, enzymes related to mitochondrial health had fallen 4.5%. For those not taking the drugs, the same enzymes increased by 13%.

Participants taking statins "were not getting the same bang from their exercise buck" as the other exercisers, Thyfault told the New York Times.

Recently, several studies have emerged outlining how statins negatively affect our body's response to exercise. Rodents given statins in the lab cannot run as far as unmedicated rats. For human marathon runners, statin use can cause increased muscle damage following a race.

The implications are important, Thyfault suggested, because "low aerobic fitness is one of the best predictors" of premature death. If statins work counter to people's aerobic fitness goals, then "that is a concern."

One possible approach to the dilemma, Thyfault said, is to improve fitness before taking the drug. He recommends discussing the possibility with a doctor before taking action.

"There's still a great deal we don't understand," he said.

If you are considering whether statins are right for you, the Mayo Clinic outlines guidelines at its website.

Statins work by blocking a substance that your body needs to make cholesterol. The Mayo Clinic advises that people with high cholesterol might consider taking statins, as might those with other risk factors for high cholesterol, including:

  • Family history of high cholesterol or cardiovascular disease
  • Inactive (sedentary) lifestyle
  • High blood pressure
  • Poor general health
  • Having diabetes
  • Overweight or obesity
  • Smoking
  • Narrowing of the arteries in your neck, arms or legs (peripheral artery disease)

Discuss with your doctor whether taking a statin is right for you. Whether or not you decide to take statins, the Mayo Clinic recommends other actions that can be taken to reduce cholesterol.

  • Quitting smoking
  • Eating a healthy diet that's low in fat, cholesterol and salt
  • Exercising 30 minutes a day on most days of the week
  • Managing stress

Common, but less serious side effects of statins include muscle and joint aches, diarrhea, nausea, and constipation.

More serious side effects, listed at the Mayo Clinic's website, include liver damage, serious muscle problems, increased blood sugar or type-2 diabetes, and neurological side effects.