A good friend of mine was into this same stuff. Had a 5K tricked bike. Was into it for a number of years. Finally he jumped off something shattered his heel, spent a month in a wheel chair and has 16 screws holding his foot together. Was in sever pain for a number of months, was hooked on pain killers for a year and a half. Another guy I know quite well, (didnt like him too much) but he was into the similar biking, but did more downhill and dirt jumps. Eventually wiped out, shoved his arm bone thru his shoulder blade. Has a plate in his back, couple 4" self tappers holding his arm on. All that stuff generally you need to have the ability (plenty of time due to no job)(hopefully good health insurance) to slowly batter your body and brain bucket in order to perfect a skill that may get you popularity if your peers are stoners.. I will say that it is impressive. So is having the balls to stick a nail thru ones hand.