According to Melody Givens of North American Sports, Ironman Arizona was the last race that featured the Clydesdale and Athena weight categories.
From now on all athletes will be only listed by their age-group and not by their weight category.
North American Sports was unique among the worldwide Ironman races in the fact that it allowed athletes to race in the Clydesdale and Athena classification.
"I also think that having the Athena and Clyds cat in Ironman demonstrates that you don't have to be a size 2 to be an athlete and be healthy. Being healthy and fit shouldn't be judged buy your belt size, it about being disciplined, training smart and educating yourself about safe, healthy training and performance," she added.
This is the second significant rules change this year for Ironman racing.
Earlier this year Ironman said it will adopt the "age up" rule starting in 2009 to establish consistency among Ironman events around the globe, according to Ironman officials. The new rule will be incorporated into all Ironman and Ironman 70.3 events.