The deaths were the second and third at the popular triathlon in the past three years.
On Monday, a New York City lawmaker called for a top-to-bottom review, questioning whether rain the night before -- which could have led to choppy water and strong currents -- or temperatures above 90 degrees were factors.
Race director Bill Burke called the deaths "a very, very sad occurrence and tragedy" but characterized the weather conditions during Sunday's race as optimal, with relatively mild temperatures and good cloud cover for much of the day. The temperature reached 89 degrees in Central Park on Sunday with high humidity, according to the National Weather Service.
Burke said participants were not required to provide a health certificate or proof they have participated in another triathlon -- things he would like to see enacted in the future.
"It's something we're going to look at and try to put possible identifiers in place that can hopefully give us some indication and let the athletes know what they need to be careful about: Have you done an open water swim? Have you participated in another triathlon? How much training have you put into this?" Burke said.
PARTICIPANTS IN THE YEARLY race swim about a mile, bike 25 miles and run six miles.
They attend a mandatory briefing before the race that includes information about training and staying hydrated. Burke said it was not uncommon for some people to struggle with overexertion. He said he most commonly sees heat-related problems such as fatigue and dehydration.
"What we try to do at all of our events is to give the athletes as much knowledge as possible," he said. That includes posting information on the event Web site and e-mailing potential competitors about training programs taking place in their communities that might better prepare them.
MICHAEL KUDRYK, of Freehold, N.J., died Sunday after he was pulled out of the Hudson River unconscious. Police say he was believed to have suffered a heart attack.
A 40-year-old woman from Elmhurst, Ill., who was not identified at the family's request, died Monday. Burke said she was believed to have gone into cardiac arrest twice after Sunday's swim.
Police said 26 other participants needed assistance for minor injuries or pains throughout the swim.
"I already talked to the USA Triathlon this morning," Burke said. "We're certainly going to take a very hard look at everything, at how people prepare for this."
Three years ago, a 32-year-old competitor was pulled from the water unconscious and later died. The medical examiner ruled he died from hypertensive cardiovascular disease, a condition linked to high blood pressure. Race organizers said he apparently was unaware of his condition.
Manhattan Borough President Scott Stringer asked organizers to conduct a full review. He cited a 2009 study by the Minneapolis Heart Institute that found athletes participating in triathlons have twice the risk of sudden death as those running in marathons. He also pointed to a recent study that found 14 people died while participating in triathlons, 13 while swimming, from 2006-08.