A 46-year-old man died of cardiac arrest Sunday just after plunging into frigid bay waters in the annual Escape From Alcatraz Triathlon, held three months earlier than usual and under much colder conditions.

The Austin, Texas, man, whose name was not released, died less than a minute after he jumped into the bay, which was about 10 degrees cooler than last year's water temperature when the race was held in June, said race director Bill Burke.

"Was it colder than normal? Yes. But in my opinion, the water temperature was not a factor at all in this tragedy," he said. "This gentleman obviously had a heart condition he was unaware of."

It was the first death in the triathlon's 33-year history, Burke said.

In all, rescuers pulled about 150 competitors from the swimming portion of the race, more than three times the normal number, he said. Water temperatures were about 51 degrees, air temperatures hovered in the mid-50s, and 11 mph winds made the air feel closer to the mid-40s.

Normally, when the race is held in June, the bay is anywhere from 54 to 60 degrees, and air temperatures can be in the 70s or higher.

The triathlon, among the most grueling and prestigious in the world, was rescheduled this year because of conflicts with the America's Cup. Next year the event will return to June, he said.

"What happened today was very, very sad. It underscores that athletes need to be checked carefully by a cardiologist before pushing themselves," he said.

The race drew 2,000 professional and amateur athletes from throughout the world for a 1.5-mile swim, 18-mile bike ride and 8-mile run along San Francisco's waterfront and through Golden Gate Park.

Athletes are not required to pass any medical tests before entering, although most are seasoned athletes. On Sunday, they ranged in age from 13 to 79 and included everyone from Olympians to those with physical disabilities.

Slightly slower winners

Although many complained about the cold, times were only slightly slower than normal.

The winners were Javier Gomez, 29, of Spain, who finished in 2 hours, 4 minutes and 27 seconds, a minute slower than last year's top finisher; and, in the women's portion, Heather Jackson, 28, of Carlsbad (San Diego County), whose time was 2 hours, 18 minutes and 8 seconds.

It was Jackson's first attempt at Escape From Alcatraz, and she did not fare well in the water, finishing third from last.

"It was horrible. It was so choppy and so cold. Every stroke was a mouthful of water," she said. "I was just focusing on getting out of the water."

She made up the time in cycling and running, pulling ahead of Olympian Sarah Groff of New Hampshire about 1 1/2 miles from the finish line.

"For me, it's always a game of chasing from behind," said Jackson, who took up triathlons four years ago after playing ice hockey in college. "This was a huge win for me."

'On top of the world'

But for most racers, the event is more about conquering personal goals than setting records.

Ray Sierengowski, 39, a food scientist from Kalamazoo, Mich., wasn't among the top finishers, but he was the happiest. He trained for 10 months, losing 90 pounds, and was in shock Sunday that he finished.

"The flood of emotions ... I feel like I'm on top of the world," he said. "Every time I felt like quitting, someone shouted, 'You can do this. Keep going.' I feel like I have 1,999 new friends."

Athletes came from as far away as South Africa, Thailand and Slovenia, many describing it as the challenge of a lifetime.

Todd Tripp, 52, a contractor from Salt Lake City who didn't even know how to swim two years ago, not only rose to the challenge but had the scars to prove it. His nose was bloodied and scratched after tripping near the infamous sand steps at Baker Beach.

"A volunteer came over and said, 'You don't need a Band-Aid, you don't need hydrogen peroxide. Just go. Just run,' " he said. "So I got up. The whole thing, what an amazing experience."