Here’s why open-water swimming can be risky, even for CrossFit athletes

In the hours after the apparent drowning death of a swimmer competing in the CrossFit Games in Fort Worth on Thursday, fans have demanded better precautions for athletes competing in an event that can be dangerous even for the most accomplished swimmers.

Lazar Đukić, 28, died near the finish line of a run-swim event in Marine Creek Lake in Fort Worth. Although the exact details of Đukić’s death are unknown, open-water swimming has always been a risky endeavor, even for the most accomplished athletes.

In general, children die from drowning at higher rates than adults do. For U.S. children between the ages of 1 and 4, drowning is the leading cause of death.

But there is a small group of fatal drownings that appear paradoxical: Strong, experienced swimmers, like Đukić, who die during a competition, even though they know how to swim and are physically strong.

“It’s not totally rare or unlikely that an elite athlete can drown,” said Dr. Andrew Schmidt, an associate professor of emergency medicine with the University of Florida in Jacksonville.

Drowning deaths among elite swimmers

The exact reasons why elite athletes drown is not clear, but researchers have begun scrutinizing open-water swimming competitions to better understand what’s happening under the surface.

One theory, Schmidt said, is something called activity-induced, swimming-induced, or immersion pulmonary edema. The condition refers to cases where athletes are found to have evidence of fluid in their lungs after intense exertion. But, Schmidt cautioned, the science on the condition isn’t definitive yet.

Schmidt, who is also a drowning education researcher, also noted that a drowning in water could happen after a heart attack, stroke or seizure.

Dr. Justin Sempsrott, the founder and executive director of Lifeguards Without Borders, said that the open-water swimming portion of a triathlon presents a unique challenge to an athlete’s cardiovascular system that’s different from other intense sports.

In many open-water swim events, Sempsrott said, a major stressor to an athlete’s heart happens at the beginning of a race, when many swimmers are starting the race at the same time. Even for athletes with healthy hearts, massive swimming starts can effectively confuse the heart’s electrical system, causing the wrong signal to send at the wrong time, Sempsrott said.

“A mass start really activates that fight or flight sympathetic nervous system, and can really drive the heart rate and physiologic stress much higher than during training,” Sempsrott said.

In a review of triathletes who died or experienced cardiac arrest while competing, researchers found that about two out of every three deaths occurred during the swimming portion of the triathlon.

The phenomena Sempsort described primarily happens at the start of an open-water swim event, when there are dozens or hundreds of athletes beginning the swim portion at the same time. This is not what happened at Thursday’s CrossFit Games event, where athletes completed a 3.5 mile run before beginning an 800 meter swim. Bystanders reported that Đukić was near the finish line of the swim when he began to struggle.

Open-water swim events can also unmask previously undiagnosed heart conditions, Sempsrott said, including in people with physically normal hearts but who have a rare genetic disorder that can be triggered by the stress of an athletic competition.

Athletes have run into trouble during swims at past CrossFit Games.

Five-time CrossFit Games winner Mat Fraser drowned and survived during a run-swim event in 2017, Men’s Health reported in December 2021, citing a podcast by powerlifter Mark Bell.

Coach Chris Hinshaw told Mark Bell’s Power Project that Fraser passed the first buoy in first place before he was passed by faster swimmers toward the end. Fraser accelerated his kick to keep up, but he didn’t have the aerobic capacity for the extra effort.

“Next thing you know, Brent Fikowski, one of the podium finishers that year, grabs him and pulls him, because he was bobbing in the water. He was going to drown,” Hinshaw said.

That same year a competitor rescued a fellow athlete who yelled for help about 120 meters from the shore at Lake Monona in Wisconsin.

In 2010, a 26-year-old open-water swimmer for the U.S. national team died during an event in the United Arab Emirates. He failed to finish and was found in the water two hours later, Swimming World reported. Water temperatures were in the mid- to high 80s. Several athletes were treated for heat exhaustion after the 10-kilometer race, south of Dubai.

‘There is something different about that swim portion’

But even as more details emerge about Đukić’s death, we might not get a definitive answer about exactly what happened in the water. Unexpected events like a first-time seizure in the water or an abnormal heart rhythm, both of which could cause drowning, are unlikely to show up in an autopsy, Schmidt said.

“There’s not an answer, but I think there’s enough data to know there is something different about that swim portion,” Schmidt said.

Absent a clear answer as to why open-water swimmers might be at greater risk, Schmidt emphasized the need for more support for lifeguards, advance planning for emergencies at swimming events, and greater education about what drowning actually looks like.

Drowning often doesn’t involve someone yelling or thrashing their arms, Schmidt said.

“Once they get to the point of drowning, they’re so tired they can’t lift their arms, they can’t yell for help,” he said.