ould exercise actually be bad for some healthy people? A well-known group of researchers, including one who helped write the scientific paper justifying national guidelines that promote exercise for all, say the answer may be a qualified yes.
By analyzing data from six rigorous exercise studies involving 1,687 people, the group found that about 10 percent actually got worse on at least one measure related to heart disease: blood pressure and levels of insulin, HDL cholesterol or triglycerides. About 7 percent got worse on at least two measures. And the researchers say they do not know why.
“It is bizarre,” said Claude Bouchard, lead author of the paper, published on Wednesday in PLoS One, and a professor of genetics and nutrition at the Pennington Biomedical Research Center, part of the Louisian State University system.
Dr. Michael Lauer, director of the Division of Cardiovascular Sciences at the National Heart, Lung, and Blood Institute, the lead federal research institute on heart disease and strokes, was among the experts not involved in the provocative study who applauded it. “It is an interesting and well done study,” he said.
Others worried about its consequences.
“There are a lot of people out there looking for any excuse not to exercise,” said William Haskell, emeritus professor of medicine at theStanford Prevention Research Center. “This might be an excuse for them to say, ‘Oh, I must be one of those ten percent.’ “
But counterbalancing the ten percent who got worse were about the same proportion who had an exaggeratedly good response on at least one measure. Others had responses ranging from little or no change up to big changes, seen in about 10 percent, where risk factor measurements improved anywhere from 20 to 50 percent
“That should make folks happy,” said Dr. William E. Kraus, a co-author of the study who is professor of medicine and director of clinical research at Duke. He was a member of the committee providing the scientific overview for the Department of Health and Human Services’ national exercise guidelines, which advise moderate exercise for at least 150 minutes a week.