This book might be a few decades old at this point.

There was a loner high school boy who realized he was good at running, and then he ran a LOT. He was training and ended up running like 20 miles a day. He shaves his head at some point. There is a black track coach at the school who I think gives him some tough love motivation. People are a bit racist in general if I remember correctly. This could be a book from the 80's.
I think he also worked on boats or at a port or something like that? At one point someone tells him his shaved head looked real funny at first because he's super tanned from working outside, but his shaved head was bright white.

Thanks!