What can we learn from the World Championships marathon about racing in the heat?
- 5 days ago
- 3 min read
This week marked the end of summer but, unfortunately for runners with fall marathon goals, that doesn’t mean the temperatures have cooled down to match *cough, thanks global warming*. After suffering through a track workout in particularly sweltering conditions this Tuesday, I found myself thinking about Susanna Sullivan, Jessica McClain, Julia Paternain and all the athletes who not only survived a 26.2-mile run but raced their hearts out and butts off in worse conditions in Tokyo for the World Championships last weekend.
Heat and humidity are nothing new for marathoners at this point, as even traditionally sure bets like Chicago and Houston have had their share of “off” years and poor weather conditions. While we typically fixate on training in optimal conditions and hitting our splits as fast as possible, there actually may be a lot to gain from looking at training and racing on a more macro level — embracing the aptitude we get from poor conditions, and preparing to race in whatever Mother Nature decides to throw at us.
Despite conditions of 82 degrees and a 75 dew point at the World Championships marathon start line (if you don’t know what this feels like, please consider yourself extremely lucky), Americans Sullivan and McClain were far from conservative in their approach and didn’t hesitate to take the lead early and run 1-2 for more than half of the race. Sullivan, a 35-year-old middle school math teacher, didn’t relinquish the lead until around the 18-mile mark and still held on to finish fourth overall — a huge improvement on her previous best in a global championship (58th in 2023 ). McClain held on for 8th in her first world appearance.
How did they do it?
To train for the conditions, McClain spent time at Arizona State’s Core Research Facilities’ environmental chamber. She ran on a treadmill as staff progressively raised the chamber’s temperature and humidity from 86 degrees and 60% relative humidity to 89.6 degrees and 80% relative humidity. The chamber can reportedly replicate environments ranging from 39.2 to 109.4 degrees and 20-90% humidity, and staff also worked with McClain’s sponsor Brooks to conduct sweat testing — as she ran, her sweat was analyzed for sodium and electrolytes loss which in turn informed her fueling strategy.
Sullivan’s heat acclimation process is more attainable for the non-professional runner. She trained in unseasonably cool conditions, so she prepared her body for Tokyo with a post-run protocol of hot tub and steam after runs. In a post-race interview with Citius Mag, she said that race day was not as bad as sitting in a hot tub after her training runs — believe it or not!
The futuristic cooling headbands from the 2024 Olympic Games were back in action as silver medalist Amanal Petros of Germany and Paternain of Uruguay both sported the Omnius product, which uses 20 pieces of graphite squares to cool the forehead. Scientists are still out on the product's efficacy, and it may do more to affect the perception of heat versus actually cooling down the body's core temperature, according to a study published after the Paris Games last summer.
Another study published last year suggests that pouring water on yourself during hot runs may do just as much to take some of the mental sting out of extreme temperatures. In Tokyo, most athletes followed this protocol — stopping early and often at every aid station to stuff ice cubes and ice packs down their sports bras and singlets, soaking their necks with cold sponges, and putting on hats with flaps to protect and cool the head and neck.
Perhaps the best strategy to deal with the toll of heat and humidity is to simply slow down. Gold medalists Peres Jepchirchir of Kenya and Alphonce Simbu of Tanzania won the world championship event in times that are eight and five minutes slower than their personal bests. After seeing a lot of blow-ups and cramping among sub-elite and recreational runners at the Berlin Marathon last weekend, maybe what the pros are better at than the average runner is recognizing and respecting the weather and making pace adjustments accordingly. Food for thought!
Sources:
Citius Mag. (2025, September 13). Susanna Sullivan, Jess McClain Finish 4th & 8th in 2025 Tokyo World Championships Marathon for USA [Video]. YouTube. https://www.youtube.com/watch?v=fxzMvZcE23Q
Hutchinson, A. (2024, September 26). Olympic Champions Are Wearing This $200 Cooling Headband. Does It Actually Boost Performance? Outside. https://www.outsideonline.com/health/training-performance/omius-cooling-headband/
Kahler, T. (2025, September 14). Arm Sleeves, Headbands, and Ice Vests: How Runners Cooled Off at the World Championship Marathon. Runner's World. https://www.runnersworld.com/news/a66094662/world-championship-marathon-cooling-methods/
Zrioka, P. (2025, September 24). From Phoenix heat to Tokyo humidity: ASU facility supports elite marathoner. ASU News. https://news.asu.edu/20250924-science-and-technology-phoenix-heat-tokyo-humidity-asu-facility-supports-elite-marathoner