I never got hurt in kickoff coverage, although I was involved in some spectacular plays. I did receive some pretty fair contusions returning the ball on kickoff returns. Some guys had a knack for putting their helmet right on your forearm on the side you were carrying the ball. I respected those guys. It was the guys who ducked last second, and threw themselves at your legs that I didn't like.
It was a weird thing though, both parties running so fast, that someone would just go flying, but it didn't really hurt.