For the study, Pandey's team assessed fitness levels of more than 9,000 middle-aged men and women with an average age of 48 who were tested twice, eight years apart.
After 18 years of follow-up, the researchers matched the results with Medicare claims for heart failure hospitalizations.
They found that people who weren't physically fit at the start of the study had a higher risk of heart failure after age 65. But those whose fitness improved on the tests had a lower risk of heart failure later on than those whose fitness remained poor.
Using a treadmill test to measure what are called "metabolic equivalents," the researchers found the risk for heart failure dropped 20 percent for each improvement in metabolic equivalents.
If a 40-year-old improved from jogging a 12-minute mile to a 10-minute mile, an increase of two metabolic equivalents, the risk for heart failure would have dropped 40 percent, Pandey said.
Data and conclusions presented at meetings should be considered preliminary until published in a peer-reviewed medical journal.
For more information on heart failure, visit the American Heart Association.
SOURCES: Ambarish Pandey, M.D., internal medicine resident, University of Texas Southwestern Medical Center, Dallas; Gregg Fonarow, M.D., spokesman, American Heart Association, and professor, cardiovascular medicine and science, and director, Ahmanson-UCLA Cardiomyopathy Center, David Geffen School of Medicine, University of California, Los Angeles; May 15, 2013, presentation, American Heart Association Quality o
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