Kids’ Exercise Predicts Adult Income

I’ll admit, this is one of those studies I clicked on because I figured I would probably like the results. And also because, as a relatively new father, I’m still trying to sort out the relative importance of all the various things I’m supposed to do to ensure my daughters become future world-beaters (or, better yet, end up happy).

The study, by researchers at several universities in Finland and published in Medicine & Science in Sports & Exercise, looked at data from 3,000 kids whose physical activity levels were assessed in the 1980s when they were 9, 12, and 15 years old. That data was then linked to Finnish tax records to determine their average income over the 10 years ending in 2010.

Among men, the results were clear: Boys who were more active by one standard deviation went on to earn about 30 percent more as adults. That relationship remained robust even after controlling for various factors like family background (including parental levels of physical activity) and weight.

Among women, on the other hand, there was no significant link between childhood exercise and future earnings. It’s not clear whether this reflects some deep difference, or whether there’s some other explanation—for example, the fact that the years when income was measured corresponded to when the subjects were in their 20s and 30s, when some women take time out of the labor market to have children.

The authors discuss several possible causal explanations for the link in boys: exercise leads to better health, which results in greater labor productivity; playing sports creates lasting networks that later help job advancement; exercise improves non-cognitive skills like teamwork, sociability, and discipline; and having athletic experience may “signal” to employers that you have good health, motivation, ambition, and so on.

There’s also the possibility that non-causal underlying factors make people more likely to be active as kids, and also lead to higher earnings as adults—for example, personality traits like ambition and motivation. The researchers tried to control for that by dividing physical activity into leisure-time play and competitive sports, but even leisure-time activity continued to predict future earnings.

One thing the authors don’t discuss is the possibility that exercise actually boosts your cognitive abilities—an idea supported by a fascinating Swedish study back in 2009 that linked increases in cardiovascular fitness as a teenager to better cognitive test scores.

Whatever the mechanisms, we probably don’t need additional reasons to think that kids (whether they’re boys or girls) should be getting lots of physical activity. Still, it’s kind of nice to think that every time I get my daughters to run around in the park, I’m contributing to my future financial security.

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