The city of Ames and Hilton Coliseum is the host site for the U-S Nationaltumbling and trampeline championships this weekend. More than five-thousandathletes are taking part. The sport will be an official Olympic event at the2000 games in Sydney, Australia. Ames Convention and Visitors Bureauexecutive director Rich Harter says the sport is a combination of otherOlympic events.Harter says fans will develop an appreciation for the sport when they seeit.The competition runs through Sunday.