New York ? Elite distance runner Ryan Shay, who collapsed and died Saturday during the U.S. men’s marathon Olympic trials, had been diagnosed with an enlarged heart but cleared by doctors, his father said.

“The thing that made him such a great runner may have killed him,” Joe Shay told the Associated Press.

An enlarged heart like Ryan’s is most commonly found in drinkers, smokers or people who are overweight, the father said. But it also translated into extra endurance – crucial for a distance runner.

Ryan and other top athletes underwent medical testing in Flagstaff, Ariz., where he trained, last spring, Joe Shay said, and he was cleared for running.

“He said the doctors told him that because your heart rate is so low, when you’re older you may need a pacemaker to make adjustments on that,” said Joe Shay, adding his son first was diagnosed with a larger-than-normal heart at age 14.

The 28-year-old Ryan Shay collapsed about 51â2 miles into the race.

“I got a call that Ryan had fallen down … then I got another call that his heart had stopped,” Joe Shay said.

The medical examiner’s office said an autopsy would be performed today.

What was supposed to be a glorious weekend for the sport became instead a wake. That somber mood is sure to carry over to today’s New York City Marathon, in which 38,000 runners will compete.

“It’s a big loss for the running community,” said 2004 Olympic women’s marathon bronze medalist Deena Kastor, who used to train with Shay in California. “It’s a day we should be celebrating. It has cast a pall.”

Shay and Ryan Hall and their wives had hoped to celebrate together after the trials. Now Hall is dedicating his race at the Olympics to Shay.

Minutes after Hall crossed the finish line first in record time, his arms raised in triumph, he heard the unthinkable news.

Hall, a 25-year-old who had never raced the distance before April, established himself as a contender in Beijing, with a trials record time of 2 hours, 9 minutes, 2 seconds. Joining him in China will be Dathan Ritzenhein (2:11:07) and Brian Sell (2:11:40).

Meb Keflezighi, the 2004 Olympic silver medalist, was hobbled by cramps in both calves and fell back to eighth.