Jonny Brownlee, the 26-year-old British triathlete and Rio Olympic silver medalist, was leading the International Triathlon Union’s Grand Final in Cozumel, Mexico, last week with just over 400 yards to go when he first showed signs of trouble. He swerved wide through a corner. His upper body leaned back and his strides turned choppy. His pace slowed. He weaved, winced, and suddenly lurched to the side of the road, his head lolling like a newborn’s.
His older brother, Alistair Brownlee, the Olympic champion who was running in third place, then came up from behind and pulled and carried Jonny across the finish line, where he immediately collapsed.
Triathlon has a history of epic last-mile implosions, especially at the Ironman World Championship, held each October in Kona on the big island of Hawaii. There’s Julie Moss in 1982, Paula Newby-Fraser in 1995, Chris Legh in 1997, and, most excruciatingly, the 1997 crawling duel between Sian Welch and Wendy Ingraham. In fact, just a few weeks ago, American triathlete Liz Baker collapsed short of the finish line at the Paralympics in Rio.
It’s not uncommon to see athletes collapse in exhaustion right after the race, but to do so just before the finish, particularly with victory on the line, is a sign that something in the body has gone truly wrong. So what is happening to these triathletes who suffer spectacular finish line failures?
Brent Ruby, an exercise physiologist at the University of Montana, has a clear diagnosis as soon as he watches the video of Brownlee and checks the race day weather in Cozumel (86 degrees and 82 percent humidity). “It has nothing to do with fuel. It has nothing to do with his lactate being too high. It has everything to do with overheating,” he says.
For years, Ruby has studied the toll that extreme heat can take on the human body. As a professor at the Montana Center for Work Physiology and Exercise Metabolism, he has tracked the link between body temperature and performance in wildland firefighters, ultra-distance runners, and triathletes. He’s also competed in numerous triathlons, including two trips to the lava-lined sauna that is the Ironman World Championship. “I remember being at mile nine [of the run] in 2010 and thinking, ‘Shit, I'm already overheating,’” he says. “It was just a nightmare the whole rest of the race.”
Humans, with our general lack of body hair and abundant sweat glands, have evolved to stay cool. Some scientists have suggested that our ability to dissipate heat might have even enabled early humans to run down their overheating prey. But these adaptations can be short-circuited by a combination of weather and intense exercise.
In drastic situations, when the body temperature spikes above 105 degrees for a half hour or more, the organs can literally start to cook, says Robert Huggins, vice president of research at the University of Connecticut’s Korey Stringer Institute, which studies sudden death in athletes and promotes ways to prevent it. Stay too hot for too long, and you can suffer liver and kidney damage, heart failure, brain damage, even death. The weaving and staggering you see in athletes like Brownlee is an overheated brain shutting the body down to try to stop the heat buildup.
Often the problem is blamed on poor hydration; news reports after the Cozumel incident note that he was treated for dehydration after the race. But while a lack of fluids can compound the problem by decreasing the liquid available for sweating—and thus cooling—“[it] is a huge misnomer that if I drink copious amounts of fluids I won't get heat stroke,” Huggins says. "You could be completely hydrated and still [suffer heat stroke]."
And perhaps counterintuitively, the talent of an elite athlete puts him or her at a higher risk of a finish-line collapse, says Chad Asplund, a triathlete and the director of athletic medicine at Georgia Southern University. He points to what some scientists have called the “central governor theory.” That is, the brain acts as a brake to keep the body from overworking itself, and mere mortals, upon receiving these signals, usually slow or stop before disaster. But Asplund, who has spent part of his career studying what makes athletes collapse, says that elites have learned to silence the alarm bells. “Elite athletes have gotten to where they are because they can manage or control a lot of body indicators that would tell you or me, ‘Hey, slow down dummy.’”
There are some quirks that make triathletes vulnerable to overheating, says Asplund. The water during the swim and wind of the bike can help keep athletes cool, but, with their internal engine revved up, the final blitzing 10K or marathon run, where there’s not enough breeze to help cool the athlete, pushes them over the edge. That said, Huggins notes that this is not a triathlon-specific phenomenon. The most common cause of heat stroke among athletes is simply running intensely, often over short distances, in hot weather. This is because the shorter duration incentivizes athletes to go all-out, pushing their temperatures into the red zone.
In fact, the most dramatic cases of heat stroke Huggins has seen are at the relatively short Falmouth Road Race, a legendary seven-mile running race along the shores of Cape Cod held on the third Sunday each August. The conditions there nearly killed marathon great Alberto Salazaar, who in 1978 was given last rites when he collapsed after the finish line. Now, Huggins and his crew from the institute have 40 tubs of ice water stationed at the finish, where they both study the runners and serve as the volunteer medical team. Last year was the worst he’s seen, with more than 100 people needing treatment for overheating, including 34 cases of heat stroke.
While an Ironman is certainly longer than seven miles, the prevalence of finish line collapses in Kona is likely due to the combination of speed—the fastest runners are finishing their marathon at or below three hours—and the fact that the race is commonly held in 90-degree temperatures.
In contrast, Ruby has studied racers at the notorious Badwater 135 in Death Valley, California—where temperatures can hover around 120 degrees—and saw little sign of overheating. At the finish line, "those guys just seem sore,” he says. “They were not completely undone like you see in some of these shorter events and even in Ironman. And that’s because the pace of the activity is so slow."
So what’s an athlete to do when getting ready for a fast run in hot weather? During a sweltering race, be sure to stay hydrated, as that facilitates sweating, and don’t ignore those alarm bells. Cooling off with ice in a bandana or a wet hat can help, but if you or someone near you starts getting dizzy, staggering, or slurring words, it’s probably time for a swift trip to the ice bath. It’s critical to cool someone suffering heat stroke within 30 minutes, Huggins says.
But the best way to avoid getting to this stage in the first place is to prepare ahead of time—that is, try to slowly acclimate to the heat in training. With a week or two of workouts in sweltering conditions, the amount of fluid in the blood can go up, resting body temperature can go down, and one begins sweating more easily. Heat acclimation can be uncomfortable and potentially dangerous, but if done right, it could save you from a spectacular finish line collapse.