At least seven countries and 36 states are being represented in Tulsa Tough's races this year.
Organizers expect those numbers to increase after registration on Friday.
The men's team from Australia's NSW Institute of Sport is getting ready for the races.
“The heat is going to play a key factor especially on Sunday when it's in the afternoon," said Scott Law, one of the pro-cyclists.
It's his second time competing in the event. He said he likes the ambiance of the races, especially on Cry Baby Hill.
"It's such an awesome atmosphere on the Sunday with everyone cheering you on," said Law.
One of his teammates, Nathan Bradshaw, is participating in the event for the first time. He said he's ready for the event, but like Law, said the high temperatures might make it a challenge.
Other athletes from out of the state are also getting ready for Tulsa Tough.