Bad news for couch potatoes that thought they were going to game themselves into brilliance (or at least game into old age, safe from senility). Researchers now say that crosswords (and other brain games) and all that are fine, but nothing works quite as well as three hours a week of aerobic excercise, according to the Wall Street Journal.

"As little as three hours a week of aerobic exercise increased the brain's volume of gray matter (actual neurons) and white matter (connections between neurons), they report in the November issue of the Journal of Gerontology: Medical Sciences. "After only three months," says Prof. Kramer, "the people who exercised had the brain volumes of people three years younger."

In other words, don't count on Dr. Kawashima to keep your wetware healthy. You'll have to get off your toucas and move more than just your thumbs. Of course, there's no reason why you can't whip out a DS while on the stairmaster and enjoy compound benefits (see World of Warcraft + exercise bike setup above).

This article was originally published on Joystiq.