Actually, I've heard a few times that motocross was one of the most demanding sport. Soccer too. But I agree that most sport at the professianal level are tough. You wouldn,t think car racing is tough, yet I remember Nigel Mansell who could barely walk after winning an Indy Cart race. He had to be pulled out of his car. How about advenrure racing? These guys barely sleep for days and face some pretty harsh weather sometimes. I got it... climbing Himalayas, that's tough. Not even sure to come back alive!