Thursday, May 20, 2010

Phys Ed: Do Our Genes Influence Our Desire to Exercise?

“Is the urge to exercise bred in our bones? That’s the intriguing question that European researchers recently set out to examine by looking at the activity habits of 37,051 sets of twins. Twins are popular with geneticists, because they provide a neat statistical model for determining whether a behavior is influenced by genetics or exclusively by environment. In the study, scientists looked at the decision to exercise or not. They turned to survey data covering twin pairs ages 19 to 40 in Australia, Denmark, Finland, the Netherlands, Norway, Sweden and the United Kingdom. Although the researchers set a very loose standard of one hour per week of light jogging or an equivalent activity to classify someone as an ‘exerciser,’ only about 44 percent of the males and 35 percent of the females met the standard. Across the board, however, the identical-twin pairs were more likely to share an exercise pattern than the fraternal twins. Using complicated statistical formulas, the scientists concluded that differences in exercise behavior were about 60 percent attributable to genes. Learning more about the genetics of active people is important, Mr. Rankinen says, because it may allow for interventions to goose everyone else. ‘Right now, most people don’t exercise, even though we all know that, for health reasons, we should,’ Mr. Rankinen says. Maybe, through our knowledge of genetics, ‘we can find ways to help make exercise easier or more attractive for people.’ If, for instance, it turns out that some people have a genetic predisposition to develop ­especially sore muscles after running, he says, ‘maybe we could start directing those people to other kinds of exercise.’ No matter how much is learned about the genetics of activity, though, the work will never provide carte blanche for physical lassitude. No blaming your DNA if you decide to skip a workout. ‘Even at the highest percentages of likely heritability’ of exercise behavior, Mr. Rankinen says, the choice to exercise is yours.”

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