I was watching the FINA championships on tv when I was in Barcelona. They were taking place there so I should have tried to go to some events in person. I noticed the swimmers and divers had different physiques. None had any discernible body fat, but the swimmers had larger muscles than divers, who are built for agility in the air. Every kind of athlete has the typical physique of that athlete. Sprinters have large upper bodies but marathon runners are slight. Decathletes are athletic in a more generic way. They have to do shot put, jump, and run various distances. Offensive lineman weigh 300 pounds. Tennis players do not look like body builders. In fact, athletes in general do not have the engorged, hypertrophied muscles of those who build up their bodies for show. They are ripped, but without those grotesque-looking, bulging muscles.
So what does an "athletic physique" look like? Generally, low body fat, no large stomachs (except maybe for some weightlifters) and muscles that are functional for that particular sport. Muscles will be large when they need to be, but they have to be strong and efficient for the particular event. Guys who spend a lot of time in the gym won't be necessarily impressed by Ronaldo's physique, or Nadal's. There are plenty of average Joes in my gym with bigger biceps, but who don't earn millions playing a sport either.*
I'm just a 53-year old guy trying to get back into shape, look slightly ripped-er** than I am. I don't need to look like an elite athlete, (nor is there any danger of that!) but I think I'd rather look like that than like a body builder with humongous but essentially functionless muscles.
*I've written this post with masculine bias, obviously, though the same principles apply to women, who also do body-building, swimming, diving, track, etc... I was noticing Stosur's marvelous upper arms in her loss to the young Victoria Duval the other day at the US Open.
**Yes, I now you can't make a comparative out of participle. Why not? What's the rule? Why can you say "shapelier" but not "differenter." ??