From all comics I have read, characters from the Marvel and DC universes are shown to have a generic muscular build. Usually male characters have similar muscular structures, only to vary in size. By generic build, I mean male characters have broad shoulders, a pumped-up chest and biceps, ripped abs and so on. Also female characters have a generic physique with a slender torso, slim hands and so on.
I know there are many main characters who don't fall under this category, characters like, Quicksilver, Blob, Kingpin and so on. Some characters don't have buffed up physique because of a certain disability or condition (Charles Xavier). They all have an exceptional reason for this however.
I mean in reality, if soldiers or sports personalities are to be considered, they are strong and hyper active. But many of them don't have the same bodybuilder-perfect physique.
For example, Cyclops could use his superpowers and still be of normal physique, as he can rely on shooting eye-beams to defeat enemies. Wolverine, on the other hand needs a good physique as he has to fight using raw strength even while using claws, but not the bodybuilder-perfect physique we often see him with such as below: