The ancient Olympic sportsmen (all men, by the way) ran, wrestled, and fought buck naked. The ancient Greeks had a tradition of doing things nude (they walked around in the buff in the bedroom and at parties called sympsia*, and they exercised without any clothes on) - indeed, the word gymnasium came from the Greek word gymos, which means "naked."
Why naked? Well, to appreciate and celebrate the male physique, of course, and as a tribute to the gods. Participants regularly anointed themselves with olive oil to enhance their looks ... and to keep the skin smooth!
In the sixth century, there was an actually attempt to make athletes wear loincloths, but this proved to be unpopular and soon afterwards nudity regained its status as fashion in athletics.
If you are not sure who the photo is of click on it and most of the time I have included the names!
Giant Rowing Bulge! (USA's Henrik Rummel)
