Sam Holness becomes the first known triathlete with autism to complete Ironman 70.3 World Championship

When Sam Holness crossed the finish line for the Ironman 70.3 World Championship in St. George, Utah, on Saturday, he became the first known triathlete with autism to compete in one of the sport's marquee races.

The 27-year-old British triathlete, who has autism spectrum disorder, has been training for this moment for more than a year. The race consists of a 1.2-mile swim, a 56-mile bike ride and a 13.1-mile run.

Sam did it while also encountering rain, lightning and even a sandstorm. The gravity of what was accomplished is not lost on him.

"I feel very proud," he said in an interview with CBS News on Wednesday, along with his father and coach, Tony. "I'm happy and I can't wait to get back to training."

Tony said that seeing his son "safe" was all his family cared about. Both of Sam's parents were overcome with emotion and cried when they saw him finish.

"I think at times, it's better to be doing the race than sitting from the sidelines watching it," Tony said. "Because once he went on the cycle, it's just, we have no control at all."

Sam completed the race in 5 hours and 44 minutes and competed with some of the best in his age category, Tony said. 

"As a coach, that's great. As a parent, it's just amazing," said Tony, who quit his job to help Sam prepare for the competition. "Actually, we sit down and we think: 'Is it real?'"

Heading into Saturday's event, training days were spent in pools, cycling and 10 to 20-mile runs, Tony said. To help recharge and recover, Sam would take naps and culminate a day's work with yoga. Part of the motivation behind taking on the sport was Sam's interest in triathlon training and his university degree in sports science.

"Two years ago, we didn't even dream of this," Tony said.

The father-son duo is far from done. Sam aims to be the first professional triathlete with autism and will compete in the London Marathon virtually on October 3, and then another Ironman race in Portugal on October 24. Their goal is to continue to inspire others.

"If you can just inspire people and raise the awareness of autism, help employers to start recruiting more people on the spectrum and do it through sport, and that's narrowing it down to what our mission is and what we want to do," Tony said.