RIO DE JANEIRO (AP) — The reasons for triathlon's burgeoning appeal are as varied as the sport itself.
—Fitness freaks looking for a new challenge.
—Millennials wanting something to hold both their interest and youthful physique.
—Gen Xers coaxed in by NBC's annual Ironman competition in Hawaii.
The biggest factor, according to USA Triathlon, is the inclusion of the sport in the Olympic program.
"Looking at the causes for this growth, one must first turn their attention to the 2000 Olympic Games, triathlon's first appearance at this international event," the sport's national governing body said in its most recent demographics report .