As temperatures neared 100 degrees Fahrenheit in Paris Tuesday, the adage imploring athletes to keep their cool took on new meaning. France’s national weather service issued a yellow alert, indicating citizens should “be attentive” to the impact of heat, particularly when playing sports.
“I hope it gets even hotter,” Greek tennis player Maria Sakkari said Monday after winning inside one of Roland Garros’ clay hearths.
For athletes accustomed to competing in warm weather, a few extra degrees could make the difference when it comes to outlasting their competitors. Bodies uniformly perform worse when overheated from exertion, but certain people have proven more adept at managing that internal, physiological challenge. Regular exposure to the conditions helps, as do modern tech and training regimens designed to boost those with lesser natural responses.
And as Earth continues to warm (the average summer temperature in Paris has reportedly increased by more than five degrees since it last hosted the Olympics in 1924), improving temperature regulation could offer the next frontier in sports analytics.
Welcome to the world of heatball.
Sportico talked to experts across performance training, diet, technology and academic research about how athletes are keeping up with today’s rising heat. Pros are turning to temperature tracking pills, sweat-measurement patches, advanced cooling mitts and vests, and, yes, the occasional cold shower. Many of their techniques could eventually trickle down to the rest of us, too.
From Pee Sticks to Ingestible Thermometers
Excessive heat presents two critical problems for athletes. First, it diverts blood away from working muscles towards the skin (in part why your face reddens under stress) to cool off. Second, heavy sweating contributes to dehydration, which can impact everything from mental performance to oxygen intake.
As recently as the 1960s, some high-level athletes were still being encouraged to drink as little as possible, wrongly told that doing so would prevent cramps or toughen them up. “Literally within the last 60 years, Gatorade was invented,” USA Cycling sports scientist and coach Michael Norton said. “That wasn’t that long ago.”
Today, athletes often have their individual sweat rates and sweat makeups tracked, either by measuring weight loss during exercise or through biosensors attached to the skin that account for fluid loss in real-time.
Pro soccer players with the NWSL’s Bay FC use Nix-made patches and pods for sweat analysis; this shows athletes the exact mix of nutrients being lost alongside water. The incoming data informs post-training ingestion suggestions, as well as planning for what and how much athletes should consume before and during hot competitions.
Team dietician Angela Bruzina says the app-based platform is a significant upgrade from the urine-testing sticks and old-school gauze pads she used in the past.
Other sensors focus on internal body temperature. Triathletes and NFL teams have even experimented with ingestible thermometer pills first developed for use by NASA to give more detailed readings. The data isn’t particularly useful in the moment—the goal is to keep internal temperatures from rising in the first place—however, it has been used to inform jersey designs and training techniques, ensuring athletes are pushing themselves, but at a pace they can maintain. Cold hard stats also help educate competitors on the benefits of proactive hydration and cooling techniques, rather than waiting for a sense of thirst or flush to reach for relief.
Embracing the ‘Long Warmup’—and a Sauna
People used to warm conditions naturally develop more efficient and faster-acting cooling techniques in their bodies, much in the same way that athletes training at high altitude have proven to return to sea level with stronger lung capacities. Hot climate-adjusted bodies produce more blood to circulate and larger sweat glands to pump water through while accelerating the speed liquids move from the stomach to the rest of the body. UK research fellow and exercise science specialist Jessica Mee said the changes can even take place on the genetic level.
As recently as 2015, only 15% of athletes were found to have acclimatized (preparing their bodies for the different conditions) before the World Athletics Championships in Beijing that August. “We’re now seeing a massive shift,” Mee said.
Athletes’ “warmups” now take place over months leading into potentially hot competitions. Ahead of the 2021 Olympics in Tokyo, the Great Britain women’s soccer team reportedly spent 90 minutes a day using stationary bikes in a heated tent, while female rowers from Canada were pulled out of the water on a cool day to erg inside a 95-degree dome.
Even passive time in a sauna has been shown to improve athlete endurance, with consistent use possibly tied to improved heart health. Trainers also believe in the mental benefits of their athletes facing rough conditions before the day of events.
“They call it ‘poor man’s altitude,’” USA Triathlon director of high performance Ryan Bolton said of sauna assignments. Mee said athletes without the ability to travel to warm environments or access heated structures might see similar benefits from a very warm bath following a workout. At the end of training, a cold dowsing is sometimes required to return the body to normal levels and trigger typical appetites.
Most of the effects of acclimatization have proven to be relatively minor in the grand scheme of elite training, maybe half-a-degree here or there. But when races can be won by fractions of a second, the changes add up.
In the Heat of Competition
It turns out that “warm up” is an overgeneralization. After months training in hot conditions, on the day of competition, athletes focus on staying cool, at least partially.
“We need the muscles warm, especially the active muscles,” Bolton said. “But we want the core temperature—and that’s what we’re always looking at, the core temperature—we want the core temperature as low as possible at the start of the race.”
You don’t need a PhD in human physiology to envision the solution: an ice vest. Athletes now regularly layer on thin torso coverings stuffed with frozen water to cool their trunks while keeping their limbs loose.
Over the last two years, Nike and Hyperice collaborated on an even more advanced device that monitors and maintains body temperature using electric systems rather than requiring the constant re-freezing of ice packs. It was tested by LeBron James and roughly two dozen other elite athletes before being deployed in Paris, where Nike-backed track competitors will have the opportunity to use the devices ahead of their events next week.
“We want to give the athletes a competitive advantage,” Hyperice founder Anthony Katz said. “Anything that allows the body to be in the state the athlete wants it to be in, we’re providing the tools for them to do that.”
At Stanford, numerous teams have adopted a different piece of homegrown technology—the CoolMitt, which circulates 54-degree water over the hand to rapidly lower internal temperatures. The equipment materialized from DARPA-funded research done by Cardinal scientists.
“If you’re a sport that has a hand that’s free, we’re trying to use a CoolMitt,” Stanford performance coach Tyler Friedrich said, listing Olympic activities including beach volleyball, indoor volleyball, soccer, basketball, and track and field disciplines. “For the first time, we actually have a piece of equipment that we can incorporate fairly easily [to cool athletes around competition].”
For athletes competing multiple times (such as tennis or soccer players), heat mitigation remains crucial after an event, as cooler cores promote recovery and appetite. This year, Paris organizers initially designed an Olympic Village without air conditioning units, but ultimately relented as several delegations brought their own AC. Night-time room temperature is among the first things Bolton checks when his team moves into a practice facility, and he surely had an eye on thermostats Tuesday night, which was expected to be the city’s hottest in five years.
The AC debate illuminated the threat to competitive balance if certain athletes from well-resourced programs are better equipped to handle hot environments.
U.S. trainers have credited heat acclimatization and mitigation techniques with the country’s recent success in marathons, for one, where Americans have won four medals in the last five Olympics after going 20 years without a podium place.
There is also the actual health risk of less-prepared athletes being pushed past their limits alongside those up to the challenge.
“The Tokyo Olympics was a wake-up call for a lot of major governing bodies that support athletes,” Mee said.
In recent years, there has been a particular emphasis put on studying female athletes. Women had previously only made up 5% of test subjects in related research, even though they are understood to thermoregulate differently due to hormone variations.
Over time, those scientific gains could drip down to everyday citizens. Sports science researchers and tech developers are already expanding their scope to consider other at-risk individuals. Because while only a select few compete for gold in extreme heat, all of us are increasingly becoming exposed to dangerous conditions.
Sauna, anyone?
