I am voting for motocross because I race motocross and play football. When I'm racing it is so much more physical than when I'm out on the field. When I finish a moto I am normally sweating so much that i have to go and take a freezing cold shower to cool myself off. In football you may have other people to worry about on your team but you get breaks every time you come off from defense or offense. Even if you were to play for the Broncos and come off and immediately need oxygen. It's the same for Pro Motocross racers at Thunder Valley except they don't get oxygen till the race is over. Plus the heat of the track the amount of fitness going into moving the bike around definitely would beat the fitness it takes for football.