I can see John and Hal staying in shape due to their backgrounds and pride (though they probably still shouldn't have Batman's physique, since they, you know, actually have lives and can't dedicate all their time to training), not so sure about Guy, and Kyle would most likely be considerably...'softer.'
I wish comic book artists would be more mindful of that sort of thing. Spider-man, Captain America and Wolverine shouldn't all have the same build.