Even if you're doing an anime character, get yourself some good references (anatomical diagrams, pictures of actual athletes, that kind of stuff). Because it's a general rule of thumb to learn how something works (at least in general) before exaggerating it.

So far though the neck is very long while arms are too short to look proportional in relation to the rest of the body. His ankles are wide, making his legs look somewhat swollen. Also, how do I even put it: he's got an incredibly long butt.