One thing apparent in the slow mo frames is the momentary expansion of the knee angle. The butt comes up, but not much and not for long. To me, what the racing class gets, even the little kid racers, and that the rest of us don't, or can't do, is that knee angle which is less than 90 degrees. It seems to reduce to quad strength. Or time in the gym in the squat cage. These clips are real things of beauty. 🙏👍💪👏