Could exercise be unhealthy for some people?

New research suggests a radical idea – that in some cases, exercise could actually be bad for healthy people, the New York Times reported.

Using data from six exercise studies involving 1,687 people, a well-known group of researchers found 10 percent of people actually got worse on at least one of three heart disease-related measures: blood pressure, insulin levels or HDL cholesterol.  Seven percent got worse on two of the measures.

The researchers told the New York Times they didn’t know why this happened, calling the results “bizarre.”

While some, such as Dr. Michael Lauer, director of the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute, applauded the study as “interesting and well-done,” others worried the study may give people another excuse not to exercise.

"I think what's important to take from this study, is that for the majority of the people - over 90 percent - improve the parameters they’re looking for," Dr. Ragno, the director of cardiovascular health and wellness at Winthrop Hospital in Long Island, N.Y., told  "Although 10 percent may have had some deleterious effects, there could be other confounding factors.  I don’t think this should dissuade anyone from exercising."

"It should really convince people to follow up with their physicians and have their markers checked regularly –  such as blood pressure, cholesterol, etc.," Dr. Ragno continued. "But overall, many studies have shown that people who exercise 20 minutes just three times a week can reduce heart attack risk by 25 percent - and forty minutes five times a week decreases that risk even further."

According to the New York Times, some critics also noted that these people who had an ‘adverse’ reaction to exercise did not appear to have higher rates of heart attacks or other bad outcomes.

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