I had a teammate in college, Mark Stickley, whose form was pretty weird - choppy little strides with very little bend in the knees, kinda shuffling along - when he was doing easy runs but when he cranked it up for workouts and races, it was a whole different story-really great form. He ran 43:19 at the Jacksonville River Run 15K in 1984 for 4th overall (1st non-African). I believe it was the 8th best American on all-time list at the time and a WR for 21 year-olds.