He was never challenged in the marathon run and clinched the most coveted title in the sport, while Swiss Daniela Ryf won the women’s title by a huge margin of more than 13 minutes.
In brutal heat and humidity, even by Big Island standards, Frodeno finished the 3.8 km swim, 180 km cycle and 42.2 km run in eight hours, 14 minutes and 40 seconds.
He beat fellow countryman Andreas Raelert by three minutes and three seconds. American Timothy O’Donnell finished third at 8:18.50.
“I am just over the world,” the 34-year-old Frodeno said in a finish-line interview.
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“Besides the Olympic title, nothing compares, nothing else matters.
“This is the Wimbledon of our sport. It's just like in tennis, if you haven't won Hawaii it's like, 'yeah'. I am so happy.”
Frodeno and his Australian wife Emma Snowsill, the 2008 Olympic women’s triathlon champion, are expecting their first child.
Frodeno, 34, stopped frequently at aid stations during the run to cool himself down with ice, figuring the few seconds he sacrificed was worthwhile.
“I had good run form, but it was brutal,” he said. “In Hawaii there's no shade at all, nothing. If you're up on the hills, your heart rate goes up and doesn't come down. The only way to get it (down) is ice.
“Everybody laughs at me for stopping but you know what, I'm a world champion, I don't really care.”
O'Donnell's wife, Australian Mirinda Carfrae, pulled out during the bike leg because of a back ailment. The defending champion, who was chasing her fourth title in Hawaii, suffered a back injury when hit by a car earlier in the week.
With Carfrae out of the way, Ryf was in a class of her own.
The 2014 runner-up finished in 8:57.57, beating Great Britain’s Rachel Joyce by more than 13 minutes. Australian Liz Blatchford finished third.
(Reporting by Tim Wharnsby in Toronto; Editing by Andrew Both)
