Hector Picard will compete in the Ironman competition in New York City later this week.
He will swim 2 1/2 miles, bike ride 112 miles and run 26 miles all without his arms.
"I've been training the past three years. But this full non-stop training has been the last 10 months," Picard said.
The 42-year-old triathlete teamed up with Dr. Matthew Klein to develop a prosthetic arm to help him compete in the grueling race on Saturday.
Picard will use the arm to help transition from one part of the race to the other.
"I have to put on my gear, my shoes, my helmet and I used the arm for a lot of that," he said.
Picard has already competed in 60 triathlons and recently completed a bike ride from Fort Lauderdale to New York City.
He lost both arms when he was 24 in a work-related accident that left him in a coma.
If Picard finishes the race, he will be the first double upper extremity amputee to do so.