Medical examiners may not know for weeks exactly why a 21-year-old student and a 40-year-old experienced triathlete died in long-distance races Sunday in Philadelphia, but the broader context is clear: Between 6 percent and 17 percent of sudden cardiac deaths are associated with exertion, and about one in every 50,000 marathoners dies in connection with a race.
"Usually when you stress your body to extremes, the weakest link is going to fail first," said John D. Kelly IV, a sports medicine expert and associate professor of orthopedic surgery at the University of Pennsylvania.
Authorities on Monday identified G. Chris Gleason, 40, a lawyer from Clifton Park, N.Y., as the man who collapsed a quarter-mile short of the Philadelphia Marathon finish line.
Jeffrey Lee, 21, a Penn senior who collapsed and died just after crossing the finish line in the simultaneous half-marathon, was identified Sunday. His time in the 13.1-mile race was one hour, 58 minutes.
Both deaths - a young man and an experienced athlete - seemed to defy stereotypes, but are not that unusual. A 32-year-old man died the previous weekend at the San Antonio Rock 'n' Roll Marathon, according to news reports, and a 35-year-old firefighter died last month in the Chicago Marathon.
While regular exercise is protective and youthful bodies can withstand more punishment, extreme stress can kill, and stress is most extreme near the end of a race.
In people under 35, an anomaly in an artery may become kinked, for example, causing spasms, Kelly said. People over 35 may have undetected coronary artery disease or a rhythm disturbance that could be fatal.
As the body works to keep cool by sweating, drinking too little water can lead to hyperthermia and heat stroke. Too much water can dilute sodium levels in the blood, causing confusion and swelling in the brain, known as hyponatremia. Both can be deadly.
Lee, who was from Cerritos, Calif., and was to graduate in May, was interested in health issues. He cofounded Alpha Iota Gamma, described as Penn's first professional health-care fraternity, and collaborated on research papers with faculty. He was enrolled in a dual-degree program in business and health care, studying in the Wharton School and the School of Nursing, said Penn spokeswoman Phyllis Holtzman.
He liked the Los Angeles Lakers and water polo, according to his Facebook page.
"Jeffrey was an amazing young man with many friends," university president Amy Gutmann said in a statement Sunday. "He was very engaged and made a positive impact in both his classes and his many outside endeavors. . . . We grieve that such a young and promising life has been taken from us so suddenly."
Gleason, a partner at the Rose Law Firm in Albany, N.Y., started running seven years ago and had competed in more than 30 running, biking, and swimming events, said his father, G. Kirk Gleason. He ran the Chicago marathon, New York City Marathon, and the Mohawk-Hudson River Marathon in Albany, his times getting faster and faster, he said.
He also completed three Ironman Lake Placid triathlons, grueling races that start with a 2.4-mile swim, then move to a 112-mile bike race, and finish with a 26-mile marathon.
A triathlete forum lit up with tributes almost immediately after his name was released Monday, many from people who had never met him but remembered his constructive comments and witty one-liners posted on the website.
Charming and self-deprecating, with a zest for life, Gleason loved to work hard and play hard, said his family. He stood at six feet, a chiseled sculpture. He was an expert skier and tennis player, but biking, swimming, and running became his passions. He enjoyed mentoring and training other athletes.
"He was just a dedicated, dedicated person," said his wife, Jennyfer. "Anything he did, he put a thousand percent. He loved it, he loved every part of it. He loved the competition of it. He loved the camaraderie." And he loved to pop a beer with friends afterward, she said.
He was also a family man. Gleason would run at 4 a.m. so he would be back home in time to get his children to the school bus with his wife. He coached their baseball and soccer teams.
"He was a great guy," said Jennyfer Gleason. "I guess God wanted his company up there."
The entire family ran - Gleason's wife, his father and mother, and his younger sister. "But Chris was the star," his father said.
It was his first time at the Philadelphia Marathon, his father said. He had decided to run with his sister-in-law, who lives here. His goal was to finish in three hours.
Gleason's wife and their two children, Ashley, 7, and Matthew, 6, had waited on the sidelines for him.
"It doesn't make sense why a strong man would drop like this," Jennyfer Gleason said Monday night.
Gleason's wife and father said as far as they knew, he had no medical condition that could explain what happened.
"He was in absolutely amazingly good shape," said his father. "And he trained very well for everything. He was very smart. It's a mystery at this point. It defies explanation."
Kelly said extreme competitions are so hard on the body that marathoners often catch a cold a few days after a grueling race.
"It is almost like all your immune faculties are marshaled to keep you alive," Kelly said.