According to a new study, reported on here by the American Physiological Society, long-term cardiovascular exercise may be more beneficial to women's hearts than to men's. The researchers separated a group of mice by gender and gave some access to exercise wheels and left the other ones to be the rodent equivalent of couch potatoes. For five and a half weeks, the researchers recorded each mouse's daily distance, time spent on the wheel and average running speed. They also used echocardiographs to monitor the mice's hearts and analyzed their RNA to see if the exercise produced any molecular changes.

The result? The female mice ended up with bigger hearts (their left ventricles increased by 15 percent, compared with the males' 5 percent), better exercise performance than the guys and a 20 percent decrease in a protein that's normally associated with heart disease (the male mice showed no decrease), according to Reuters Health. The study's lead researcher, Sebastian Brokat, says the findings "bring us a step closer to explaining the sex bias in physical activity that protects the heart."

Reading about the exercise differences between mouse genders reminds me of another article I meant to write about a while back (warning, this has nothing to do with mice or heart disease) -- it's a piece by Cynthia Gorney in Runner's World about a transsexual named Janet Furman Bowman who used to be Jim Furman. Why is this piece in Runner's World? Because Bowman -- a serious runner -- is one of the only people in the world who knows firsthand how one's athletic performance would be affected if one were the opposite sex.

I won't go into too much detail here (the article makes a great procrastination break), but the gist is this: Despite keeping the same training regimen, Bowman is slower than Furman was -- becoming female left her athletically disadvantaged compared with where she was as a guy. Interestingly, her rank has remained basically the same; she tended to have times in the 75th percentile for men, and she now is roughly at the same percentile as a woman. It's just that the absolute numbers are a lot slower.

Bowman says the drop in times is "the one regret" she has about becoming a woman. But hey, if the mouse study is right, at least Bowman's sex change may have left her with a healthier heart.