Summer sizzle separates men from women.

If a man's out running and gets hot, he loses the shirt. No problem. Doesn't matter if he's a Clydesdale with a bit of a gut: when humidity closes in, time for bareback running.

For women, the question of running shirtless is more complex. Women don't impulsively shed their shirts. To run with just a bra is a decision a woman makes in advance, taking many variables into consideration first.

A woman gives a lot of thought to how she'd look running in just a bra and shorts before doing it. It's not an impulse decision based on bodily comfort. Her personal bra history and past traumas figure into the choice she makes.

My most-memorable bra trauma was in 1971 when I was 15. My 60- something male track coach told my mother I needed a "more supportive" bra. This meant he actually noticed I had breasts. To say I was mortified would be a severe understatement.

My mother marched me through the department store asking all the clerks in the lingerie department if they had a "running bra" that would help me "stay put." The clerks must have found this a novel question, because they all gathered 'round, eyeballing my breasts and scratching their heads. I walked out of the store in a bra with six hooks in the back, straps an inch wide and made of some non-breathable, non-stretching fabric. My mother looked pleased.

This is the kind of bra trauma a woman does not forget. It lingers and colors all future bra decisions. Even when the first colored and patterned running bras came on the market, wearing just a bra to run in wasn't a choice for me. Like many women my age, I had been programed to view the bra as a white undergarment.

Combine a bra trauma like mine with most women's fear of falling short of the media ideal of the perfect-shaped woman, and you've got a whole lot of women who won't shed their shirts.

So what's the big deal? Shirt, or no shirt. The big deal is women should feel that they have a choice. Women should feel OK about impulsively whipping off the shirt when they're hot. We should be free to focus on comfort, rather than fear of being seen as "too little" or "too big." This is the one time women should think more like men.

It's time to stop over-thinking the shirt issue and embrace the many shapes of women runners. Stop zeroing in on that stretch mark: it's a natural sign of motherhood. Stop zeroing in on that little, or even big, roll around your middle: you're a runner, a strong, fit woman runner, who has the choice - shirt or no shirt.

Next time you're feeling the summer sizzle, know that if you feel like it, you can shed the shirt. MR

Ann Forshee-Crane, a freelance writer who has been running for 35 years, occasionally sheds the shirt.