hmmm, I've only seen rugby a couple of times in my life, so I don't know if it's really the same as American football.
There are quite a few injuries in the American game in spite of all the padding, especially on pass plays where you have a receiver running across the middle of the field, turns to catch the ball, and *WHAM* the defensive back gets there right as the pass is completed. I wonder how those guys survive some of those hits, it is brutal!