The first 283 runners were analyzed at 15k of a race in Japan in 2004 and 75% landed on their heel and only 4 landed on the forefoot. This being the opposite result of what Pyrie claimed some guy found at the olympics in 76 I think. But better technology may have been used in 2004 and also possibly the other guy was looking at sprinters? Sadly Pyrie isn't considered the most reliable guy.
http://www.runnersworld.com/community/forums/runner-communities/barefoot-running/someone-ever-research-this-heel-vs-midfoot-study
The replies are somewhat humorous to me. People find ways to believe what they've decided they're going to believe.
Anyway I AM trying to run as fast as the first 283 people in that race, although I've still got some work to do.
Have been completely injury free since I started heel "striking". No knee pain at all anymore. No pain anywhere. Not even getting sore at all and I've really been running hard.