I've never ran on a team, so maybe that's why I don't get it, but where I live there are several college / high school cross country teams. When I see groups of guys running together, they all have their shirts off.
What's the deal?
Seems like some sort of peer pressure to be manly or something. Or does running with other guys make them feel more confident?
Either way, I like having a shirt to wipe off sweat. More laundry I suppose.