This is my favorite artistic time period. The Greeks were so open and relaxed with not only their own but other peoples bodies as well. Of course the male figure was reverenced more so then the female, probably because they saw the men as being the power (or head) of the household. Their mythology is extremely fascinating and their Gods and Goddesses were so beautiful that I think that the men especially wanted to be seen as beautiful as the Gods. I can certainly understand why they would participate in their sports in the nude. I can see why clothes would get in the way and also be hot while participating. Of course I have no idea what the temperatures were like in those days, but I would assume it was very warm if not down right hot.
I think it's a shame that people today find the human form obscene, I know that doesn't apply to all people, but to enough that we will never have that freedom again. I don't think we are all that different today except that it's the female form that has taken precedence to the male. Strip bars with nude dancers, or at least partially nude, magazines, movies, television, and even web sites show nudity. The biggest difference in us today and the Greeks is that the Greeks were open with nudity. Nudity was a way of life, something they saw everyday from just about everyone, and no one thought anything about it.
Just about any artisan that you study today has some nudes in their work. The human body, no matter in what shape or size it is, is beautiful and wonderfully made. I wish everyone would have a open mind, there are people who talk about all the beautiful things God has made; sunsets, sunrises, mountains, oceans, etc., but the most beautiful thing God ever made were people, men and women and children, we need to learn to appreciate them in all their glory.