It seems that they might as well run naked, with their skimpy tops and bottoms. Is skimpy dressing really much more efficent against wind resistance. ~ over the typical running wear?

Yes, they dress light to keep cool. They also dress light to get the attention of their male peers. It may sound stupid, but it's true.

The guys are practically naked too, your just a man and notice the women...

Well less layers helps the women run faster. More layers will slow them down.

i don't think so. where are their titis?

It makes them run faster.If I was dressed like that I would be running as fast as I could.

You would be surprised at the difference that having light clothing makes. The less clothing you wear, the less weight you're carrying and the less quickly your body heats up.

When you run, especially in the heat, your body naturally produces sweat. Sweat in turn evaporates off of your skin, which significantly cools it. When clothing covers that skin, it prevents the sun from evaporating that sweat as quickly.

Perhaps even more crucial, more clothing means extra weight. Even a fraction of an ounce can mean a precious second or two in a race; that's part of the reason racing shoes are built as light as possible.

Now, when you're training, the light clothing isn't necessary. But when you're racing, it helps, and it's worth it.

And I can guarantee you that the majority of runners do not wear the clothes for practical reasons, not to show off.