Always remember kids are extremely durable. If not, the human race would have ceased to exist long ago.
My four-year old loves to wrestle with me (he always wins, wink!). Two older girls and his older brother were never real physical or into sports, but this one sure is. It's amazing how he somehow knows to go for the neck and go for it hard. I've never taught him that, and in fact I strongly try and discourage him from it. But when he gets going and really is trying to beat me, he'll grab the neck, stick his elbows in my neck and even stick the point of his chin in my neck. Hard, too! If I rile him up too much, he's even punched me, and of course, it's in the neck. I'd punish him harder for this, but a part of me has decided it's nature's way for a child to fight back the only way they really can if confronted with a real dangerous situation. So I cut him some slack. But I dread getting a call someday from a school counselor telling me my son was trying to choke some other kid on the playground.
There are no manufacturers manuals, or even Clymers or Chiltons manuals for raising kids. It's all judgment calls and we do the best we can every day. There are a lot of books out there, but I decided a long time ago that any idiot can sit and type a book and act like an "expert," but every single child (and parent) is completely different and no one can tell you exactly what to do or how to do it.
Of course, we can all look at the way some parents raise their kids and know what NOT to do!!