This morning I saw something very strange. I went to do 200s on the indoor track at my school, and some guy was doing the most bizarre workout. He was running in lane 1, but he would only run 100m, then stop short, turn around, and run 100m back the other direction. Every 5-10 minutes or so he would run about a mile going in one direction the whole time, then go back to his back and forth thing. I was kind of irritated because he had basically claimed lane one for himself (even put his track bag down in the middle of the lane right at his turn-around spot), but I was also really curious about what he was doing. Does anyone have any idea what the benefit of a workout like this would be?