Is There A Laziness Gene?

Have you ever wondered why you can't get off the couch and exercise despite paying for an expensive gym membership, despite your New Year's resolutions, even despite the doctor's scolding at your last check-up? Turns out that your inertia may be coded right into your genes. Based on some intriguing, preliminary studies in animals, J. Timothy Lightfoot, a kinesiologist, and his team at University of North Carolina, Charlotte, suggest that genetics may indeed predispose some of us for sloth.

Using mice specially bred and selected according to their activity levels, Lightfoot identified 20 different genomic locations that work in tandem to influence activity levels in mice specifically, how far the animals will run. Lightfoot's team is the first to identify these genetic areas, and the first to figure out that they function in concert. The researchers say the areas they found on the mouse genome may have analogs in humans, and the UNC team is now gearing up to conduct a similar study in men and women. "We have put forward a fairly complete genomic map of the areas that are associated with regulation of physical activity," says Lightfoot, whose study is published in the current issue of the Journal of Heredity.

Lightfoot, who originally wanted to coach college basketball and is himself an avid athlete, began studying activity levels as a way to try to figure out why, given all we know about the overwhelming health benefits of physical activity, so many people still choose not to exercise. A lecture at Johns Hopkins about genetics and lung disease served as Lightfoot's eureka moment, and he became interested in studying genes as our prime mover. For the new study, Lightfoot and his team bred two strains of mice active and inactive. Researchers then cross-bred two generations of the active and inactive mice, ending up with a study group of 310 genetically mixed offspring. At about 9 weeks old, each mouse was housed in an individual cage and given an exercise wheel. Researchers measured how far, how long and how fast the animals ran every day for three weeks, at the end of which the mice were genotyped.