I believe that Motocross should be in there somewhere. 3 thirty minute moto heats ten minutes apart over incredibly rough terrain at very high speeds, finding yourself 30 feet or more in the air over jumps, plus the added bonus of pretty certian serious injury if you crash at speed. World class motocrossers have to be in unbelievably good aerobic condition to do what they do, you see a lot of old boxers or wrestlers but a 30 year old world motocross competitor is extremely rare. That is a real burnout sport.
