medifag here, not from US and so far we haven't had any class directed on physical training/optimal nutrition balance, we know baseline stats, but that's why sports medicine is a medical specialty I suggest you go see a certified personal trainer, Internal medicine and cardiology specialists know some stuff about cardiovascular pathology and whatever could be related with sports and them, traumatologists know how to treat bone and muscle strains but not much more than that, also some nutritionists are as smart as a fucking chimp they never split macros or analyze and personalize a dietary program, you'll end up learning more from a Lyle McDonald book
tl;dr go see a personal trainer