Contact is not allowed in Organized Team Activities, but that didn't prevent a major collision at a recent Vikings workout.

Except it didn't happen between two players. Instead it involved second-year running back Ian Johnson and head coach Brad Childress.

Johnson, who spent last season on the practice squad, was running a swing route out of the backfield. Like most coaches do, Childress was standing on the field to get a better look at the play developing.

Johnson recalled what happened:

"I'm just running my route and my eyes are always fixed on the quarterback. So as I'm getting width I don't know what's coming. I trust the quarterback that he's not going to throw me into a headache.

"I got hit by something and go up over my feet, end over end. I did a flip. My first instinct was, 'Oh, I'm going to hurt whoever this was because someone just cheap-shotted me.' I look up and I see it's Coach Childress. He's on the ground and I'm like, 'Oh no, that's my ticket out of here.' You don't do that to the head man. "I sat there for about two seconds and he popped up and said, 'Oh, I'm sorry. That's my fault.' I was like, 'Whew, maybe I'm not out of here.'" The media was not present that day of OTAs, but witnesses say it was a major collision and that both Childress and Johnson were lucky to escape serious injury. "We hit hard," Johnson said. "He had a bruise. I had a contusion on my knee for a while. I hit him right on his inner thigh and knee cap." Like Brett Favre after the NFC Championship game, Childress has pictures of his bruised leg. Playground build: The Vikings are holding their annual playground build today at Nellie Stone Johnson Community School in North Minneapolis. Players, coaches and members at all levels of the organization will participate in building a new playground for the school. This is always a great event and we will bring you highlights later today.