In this Jan. 17, 2015, file photo, Chase Outlaw, of Hamburg, Ariz., dismounts Sun Dome during the Professional Bull Riders Buck Off, in New York's Madison Square Garden. Serious injuries are occupational hazards for bull riders, but doctors, riders and researchers say the most pervasive injuries are concussions. The Professional Bull Riders' circuit's lead medical staffer says he hasn't seen a drop in the number of concussions despite the widespread use of helmets.
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