TUESDAY, Aug. 9, 2005 (HealthDay News) -- Researchers have identified a genetic trait that may help to explain why some older people get fewer benefits from physical activity than others.
It's a variant form of the gene that controls a molecule called angiotensin-converting enzyme (ACE), which is involved in blood pressure regulation. A British study had previously found that the variant gene affected the physical response of Army recruits who carried it, said Stephen B. Kritchevsky, professor of gerontology at Wake Forest University School of Medicine.
So Kritchevsky and his colleagues did genetic testing on the more than 3,000 older people in the Health Aging and Body Composition Cohort Study.
Those people, ages 70 to 79 when the study started in 1997, have made periodic reports of their physical activity -- not only exercise but also everyday activities such as walking and stair climbing. They also have reported any mobility problems they might have.
The researchers said the study was the first to show that the gene that controls levels of ACE may be associated with physical function in older adults.
The scientists found that older exercisers who inherited a gene combination associated with the lowest ACE production were 45 percent more likely to develop difficulties with climbing stairs or walking a quarter-mile, compared to exercisers with gene combinations associated with higher levels of ACE.
The most active people, those who burned more than 1,000 calories a week in physical activity, were 33 percent less likely to report mobility problems, said the report in the Aug. 10 issue of the Journal of the American Medical Association.
"One of our most important findings was that everybody did better with exercise," Kritchevsky said. "But people with this genotype did not get the best response."
This is "one of the first studies to observe such an interaction between genes and behavior," he added.
Colin Milner, chief executive officer of the International Council on Active Aging, said, "We've known that some people are genetically predisposed to getting greater results than others. All you have to do is look at the athletes out there. Some people can just run, jump or whatever better than others."
Milner said the study has a personal meaning for him, one that other people might take to heart.
"My buddy and I work out regularly, and he gets better results than I do," he said. "I can get frustrated, and I have to keep that feeling from interfering with my exercising."
Similar genetic studies might have a great impact in the future, Milner said. "In the next decade or two, we might do programming around someone's DNA," he said. "A fitness center could extract a bit of DNA and figure out what someone's exercise program should be."
But that future might be distant, Kritchevsky said, because the new study "is in many ways still preliminary and requires confirmation."
Yet the message today is clear, he said: "Keep exercising. That's the bottom line."
The American Academy of Family Physicians offers exercising tips for older people.