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Inside the Brain Trust of Triathlon Research

What do you get when you comb through mountains of triathlon data? An evidence-based strategy to keep triathletes safer than ever before.


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Every year from 1982 to 1984, orthopedic surgeon Dr. W. Douglas B. Hiller, toed the line at the Hawaii Ironman. But in the annals of triathlon history, Hiller will be remembered for something else entirely.

It all started in 1985 when Valerie Silk, who’s considered the “mother” of triathlon for her efforts overseeing Ironman in the 1980s, asked Hiller to become the director of research. As the clinical professor in the Washington State University Elson S. Floyd College of Medicine, the ability to collect and analyze data was certainly a skill set Hiller could put into play. What started as a small side project became a lifelong effort to study endurance athletes and develop evidence-based conclusions on how to make triathlon safer.

In 1989, Hiller became one of the first three members of the medical committee for International Triathlon Union (now World Triathlon) and has been on the medical committee ever since, also serving as the chairman of the committee for some 14 years. He was also involved with drafting the first set of medical guidelines for what would eventually become USA Triathlon. Those guidelines covered optimal fluid intake, how medical treatment at Ironman races should look, and other health and safety topics that prioritized athlete well-being above all other logistical considerations.

Over four decades of triathlon research, Hiller has become the go-to resource for many of the sport’s top organizations. It was natural, then, that a new research initiative by World Triathlon would place this analytical mastermind at the helm.

The new partnership between World Triathlon and Washington State University, announced in May 2022 and described as “a curation of all medical data for World Triathlon,” has the potential to answer some of the biggest questions about keeping triathletes safe, healthy, and fast.

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Crunching the numbers

In 2003, Hiller began to take custody of all the handwritten medical cards from every medical encounter that transpired at endurance triathlon events from 1989 onwards. If an athlete required a bandage after a bike crash or an IV in the post-race med tent, it was documented and logged. More recently, co-curator Dr. Christopher Connolly, associate professor of kinesiology at Washington State University, took over management of the data and development of a robust database to crunch the numbers and build a system for gathering and analyzing volumes of more data in the future.

Organizing and assessing the data already in existence has been a massive undertaking; Connolly’s team has spent roughly 4,000 hours digitizing the data and creating the massive Global Triathlon Safety Database. It launched in 2019 at Washington State University and now curates medical, performance, and environmental data on ultra-endurance triathletes worldwide. All data is stored in a HIPAA-compliant way that protects the privacy of all athletes.

Connolly, a swimmer who has yet to do a triathlon himself, refers to the trove of information they already have as “sacred data, because we wanted to honor the athletes and the legacy of people like Dr. Hiller and so many who’ve worked with him.”

Hiller (L) and Connolly (R) outside their offices at Washington State University.

The database has already yielded insights into making triathlon safer, and many more best practices are expected to come, now that Connolly and Hiller’s team have officially partnered with World Triathlon to curate all medical data from their events and conduct research on how to actively address health and safety issues in the sport. These issues include everything from preventing heat-releated injuries to assessing sex differences in injury rates across triathletes.

But conducting thorough research on decades of triathlete data isn’t a matter of just putting some numbers into a spreadsheet. “It took a while, because this is the first time we’ve done anything like this. My research team and I have looked at a lot of stuff, but not this kind of data in this quantity,” Connolly says.

“We don’t know what we’re doing until we look at what we’ve done,” Hiller says. “And then we don’t know what we’ve done until we really look at the numbers. When you look at the numbers, there are things that are very obvious.”

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Cracking the hyponatremia code

Through deep analysis, the team has already published a number of papers identifying best practices for health and safety in triathlon.

Right from the beginning, the sport presented a few areas of concern. One that emerged early on was the potential for athletes to develop hyponatremia, a condition which occurs when a person drinks so much water that they dilute the concentration of sodium in the body. Sodium is an important electrolyte that helps the body regulate the fluid content in cells and maintain normal blood pressure levels. It’s also critical to normal nerve and muscle function. While rare, hyponatremia can turn deadly in extreme cases.

Hiller says the first study ever done looking at hyponatremia in triathletes came about at the 1984 Ironman; the medical team drew blood from competitors and found that there were a number of athletes who had the low-sodium condition, “which was completely unexpected for us,” Hiller says. At the time, hyponatremia, sometimes called “water intoxication,” was completely unknown.

Hiller and the team subsequently published a paper presenting these findings, which further indicated that the type of fluid given to an athlete experiencing hyponatremia can sometimes make the situation worse. If you give water to a hyponatremic individual, you’re only further diluting the sodium in their body. Instead, that person needs fluids that contain electrolytes – more specifically, sodium.

This analysis led to a recommendation to alter the types of fluid being offered at aid stations in the Kona Ironman going forward. “It also changed the fluids that people around the world were using,” Hiller says. Over the years, the collection of data at races has furthered the understanding of hyponatremia, culminating in the development of best practices for athletes undertaking an endurance event. When you hear recommendations on which sports drink to consume and how often, all of that can be traced to its origins in Hiller’s work.

RELATED: How Sweat and Hydration Needs Differ for Men and Women

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A treasure trove of triathlon information

Connolly says that while some of the team’s analysis of the data they already have is still preliminary and hasn’t been fully finalized yet, they have teased out several other actionable pieces of information. One such data point is how the rate of injury is higher in female triathletes than in their male counterparts. While they aren’t entirely sure why this has been the case, Connolly says the incidence of injury in female athletes has declined over the years. The assumption is that improved treatments and coaching practices have helped female triathletes train more effectively.

The team has come up with some additional interesting findings (that are likely to be published in the near future) regarding:

  • Cramping – Exercise-associated muscle cramps appear to be more common in male triathletes than female triathletes and among older competitors than younger competitors. These cramps are potentially related to dehydration.
  • Sex differences in symptoms of hyponatremia – Male triathletes experiencing exercise-associated hyponatremia are more likely to show symptoms of an altered mental state and diarrhea, while female triathletes tend to vomit when they have exercise-associated hyponatremia (EAH).
  • Common medical events and treatments – The most common medical events observed at a single Iron-distance race between 1989 and 2019 were dehydration and nausea. Forty-eight percent of those medical visits were treated with intravenous fluids. Of the athletes who received medical care, 13% did not finish the race, and 1.7% required transport to a hospital for further treatment.
(Photo: Charlie Crowhurst/Getty Images)

Another current “hot” topic in triathlon safety is our warming planet and how to set safe boundaries for competition. It’s intuitive to think that heat-related injuries, of which hyponatremia can be one (the more you sweat, the more sodium you excrete), might increase as temperatures rise, particularly among Iron-distance triathletes covering long distances. But as Hiller notes, “there’s very little objective data on that.”

In fact, what the data do show is that the longer the race, the less likely the athlete is to experience heat-related complications. The team suspects this may be because the intensity of racing is often much higher in shorter, sprint triathlons than it is in the long-haul events like iron-distance races.

What’s more, when you’re racing at a super high intensity, you’re moving too quickly to take in as much water. “The people who do tend to become hyponatremic are people who drink too much, which tends to be people who are going slower,” Hiller says. “People who run six-minute miles at Ironman are not likely to end up over-hydrated.”

RELATED: Hot Stuff: The History and Science of Heat Acclimation

The longer the race, the less likely the athlete is to experience heat-related complications.

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More data = More answers

Currently, the Global Triathlon Safety Database is receiving information from events all over the world. Always, privacy of the individual athlete is the first order of business. Every athlete must sign a consent form for their anonymized data to be collected, stored, and analyzed. Even the names of races are scrubbed – only the medical data points, the course terrain, and environmental conditions during the race are retained so that no single data point can be traced back to a particular race or athlete.

Using this ever-growing body of data points, the team is also actively investigating why deaths during triathlon almost always occur during the swim. Though these tragic death are extremely rare, “but nobody really understands why that happens,” Hiller says.

RELATED: Solving the Mystery of Swim Deaths

Understanding exactly what occurred and whether it can be prevented is the driving spirit behind the Global Triathlon Safety Database project. Through the sheer volume of data the project has gathered and will continue to collect, the hope is that some answers will emerge. This may in turn lead to recommendations and guidelines for future events that could help prevent deaths during triathlon training and racing.

One challenge in finding concrete evidence that applies to all triathletes is the wide variation of participants within the sport. “The bottom line on it all is that every person has a red line,” Hiller says. “This red line varies from person to person – for some it’s a 10-minute walk, for others, it’s running multiple four-minute miles. This can make developing best practices and guidelines challenging, because there’s so much variability.”

Still, Hiller says a common theme is recognizing that “there are physiological limits we all have.” Listening to your own body, despite what other athletes or coaches around you might be saying, is critical to ensuring your own safety, not to mention enjoyment of the sport. You’re a sample size of one, and while data from many other athletes can help inform the development of strong safety guidelines, Hiller says ultimately each athlete is different. Data and best-practice advice is immensely helpful, but it’s not one-size fits all.

Knowledge is power

At its most basic level, the partnership between World Triathlon and the WSU team is about deriving power from knowledge. “When triathlon started, nobody knew anything,” Hiller says. “There was almost nothing written on the physiology of it.”

The complex and strenuous undertaking of swimming, biking, and running in quick succession was a novel enterprise in the 1980s when the sport developed. Over the last 35 years or so, many insights have emerged, and thanks to the WSU team’s efforts, we can expect more analysis leading to safety breakthroughs going forward. For Hiller, his vocation and his passion are one and the same.

“I don’t know why I’m so obsessed with this sport, but when I met it, I fell in love with it. And I’m still here,” Hiller says. “I decided that I can’t race, but what can I do and still help? This is it.”

Both Hiller and Connolly note that this project is a “dream partnership,” and their mutual admiration of their work has made the collaboration professional and personally fulfilling. Working with Hiller, who he calls the “godfather of it all” has been nothing short of a professional coup, Connolly says.

“His knowledge is unparalleled in the field, on not just the sport and athletes but also on the administrative side and working with these organizations. There are few people that really live up to their reputation and their hype, and Doug is one of those people. Every good thing you hear about him is true. And his contributions to the sport are legendary. It’s just been a dream partnership for us and we anticipate a lot of very pivotal findings. We’re excited to get this information out to the sport.”