Surely not quite as skimpy as Tom Daley's swimming trunks?
Never quite sure why the athletes wear them, as the girls always seem to be 'removing a wedgie' at the finish line!
some male athletes do wear them, like tom daley, and some of the outfits worn by the runners leave little to the imagination. The bikini's worn by the beach volleyball girls seem daft but then i'm not a bloke.
It's fashion more than anything else . I don't think it helps - you lose a lot of heat from your midriff . I noticed the three medallists in the women's marathon were all wearing traditional running vests .