For competitors in the upcoming Western States 100 on June 28, almost nothing is more important than staying cool in this hot, sunny trail race. The same is true for all runners training and racing in the summer heat.
That’s because running long distances represents a battle against rising body temperature. The longer and faster you go, the more your core temperature climbs.
The brain interprets this as a danger signal: Warning! Warning! Beware of heat stroke! As a result, the brain moves blood to the skin rather than the leg muscles.
With less oxygen-rich blood reaching the muscles, a runner must slow down. This is why Western States participants focus so much on cooling strategies. If they keep their body temperature under control, they can run faster.
You can use the same methods to improve your own running and racing in hot weather.
Here’s how.
Step One: Heat Acclimatization
The annual Western States 100 is known for high sun and hot temps (often over 100 degrees F) in the midday, middle miles.
Since the first rule of heat acclimatization is practice in race-day conditions, top contenders like Kilian Jornet, David Roche, and Rod Farvard have devoted substantial time to heat training. This is particularly important for Jornet, who lives in Norway, where he often trains and races in cool weather.
In fact, many Western States elites have adopted a recently popular mantra: “Heat training is the new altitude training.”
Research supports them. A meta-analysis1Tyler, C. J., Reeve, T., Hodges, G. J., & Cheung, S. S. (2016). The Effects of Heat Adaptation on Physiology, Perception and Exercise Performance in the Heat: A Meta-Analysis. Sports Medicine, 46(11), 1699–1724. on “The Effects of Heat Adaptation on Physiology, Perception, and Exercise Performance in the Heat,” it was concluded, “Heat acclimatization had a moderate-to-large beneficial effect on lowering core body temperature before and during exercise.”
A recent 2025 paper from Frontiers in Physiology used a randomized controlled trial to uncover a lesser-known benefit of heat training. It “reduced carbohydrate oxidation during submaximal exercise in the heat, indicating improved muscle glycogen utilization efficiency.”
In other words, you can run farther while burning fewer carbs. That’s a big gain. So, to perform well in the heat, you must first train in the heat.
Chill Out Before The Start
Months before the hot, hilly Athens Olympic Marathon in 2004, American runners Deena Kastor and Meb Keflezighi attended a special “science of marathon running” camp hosted by the U.S. Olympic Committee. There, they learned that wearing an ice-filled vest just before a hot race could improve their marathon time.
Both used this tactic in Athens, and both took a podium position in the Olympic Marathon: Kastor placed third, and Keflezighi second.
A scientific review of cooling vests has confirmed their value. The paper in Bioengineering2Fernández-Lázaro, D., Felipe, J., Corchete, L. A., Miguel, Santamaría, G., & Jesús Seco Calvo. (2023). Is the Cooling Vest an Ergogenic Tool for Physically Active Individuals? Assessment of Perceptual Response, Thermo-Physiological Behavior, and Sports Performance: A Systematic Review and Meta-Analysis. Bioengineering, 10(2), 132–132. https://doi.org/10.3390/bioengineering10020132 found that cooling vests significantly reduced skin temperature and thermal comfort, allowing runners to “maintain intensity for longer” by “delaying the onset of fatigue due to hyperthermia.”
Bottom line: The use of cooling vests is “a technique that influences perceptual response, thermo-physiological behavior, and sports performance.” Vests are effective in part because they are big, covering the shoulders and torso.
Downside? Vests packed with ice or frozen gels are heavy, so few will choose to wear them while running.
Drink Often, Drink Modestly
Runners have long understood that hydration is essential to endurance performance, in part because dehydration leads to a lower sweat rate, which reduces the body’s key cooling mechanism. However, the ins and outs of appropriate fluid consumption remain complex and not well understood by many. This results in part from the huge variation in individual sweat rates.
Decades ago, we were told to replace all the fluids we lost while running. In other words, maintain body weight. A newer consensus statement from the International Olympic Committee3Racinais, S., Hosokawa, Y., Akama, T., Bermon, S., Bigard, X., Casa, D. J., Grundstein, A., Jay, O., Massey, A., Migliorini, S., Mountjoy, M., Nikolic, N., Pitsiladis, Y. P., Schobersberger, W., Steinacker, J. M., Yamasawa, F., Zideman, D. A., Engebretsen, L., & Budgett, R. (2022). IOC consensus statement on recommendations and regulations for sport events in the heat. British Journal of Sports Medicine, 57(1), bjsports-2022-105942. https://doi.org/10.1136/bjsports-2022-105942 advises that there’s no health or performance risk in losing up to 2% of your body weight while running.
In fact, elite runners often lose 6% of their body weight during fast marathons, according to a study published by the Clinical Journal of Sports Medicine.4Beis, L. Y., Wright-Whyte, M., Fudge, B., Noakes, T., & Pitsiladis, Y. P. (2012). Drinking Behaviors of Elite Male Runners During Marathon Competition. Clinical Journal of Sport Medicine, 22(3), 254–261. https://doi.org/10.1097/jsm.0b013e31824a55d7 Haile Gebrselassie clocked in at minus 9.8% in winning the 2009 Dubai Marathon in 2:05:29.
In the early years of the Western States 100, runners were forced to drop out if they lost more than 7% of their weight as monitored at checkpoints. Now that stance is much more nuanced. Weight is just one of many data points in a participant’s medical evaluation.
Current hydration guidelines recommend a two-pronged approach. First and most important, have a plan.
If you are someone who sweats heavily and needs to drink frequently, stop often at aid stations, and/or carry your own fluids. The IOC notes that an average fluid intake may range from 17 to 34 ounces per hour. Some, however, need to drink much more.
Second, drink according to thirst. This won’t prevent you from losing some body weight, but should keep you in the healthy and high-performing zone.
The Pause That Refreshes
In addition to hydrating carefully, most runners have at some time poured water over their head during a hot race. This isn’t just simple; it’s also effective.
According to a 2024 randomized, controlled trial5Anderson, M., Bellenger, C., Chaseling, G. K., & Chalmers, S. (2024). The Effect of Water Dousing on Heat Strain and Performance During Endurance Running in the Heat. International Journal of Sports Physiology and Performance, 19(11), 1291–1298. https://doi.org/10.1123/ijspp.2024-0044 published in the International Journal of Sports Physiology & Performance, “water dousing” significantly improved performance in a 10K. It would likely be even more effective in longer races.
Also helpful: dashing through “misting stations” provided by race organizers, or front-yard hoses from friendly spectators. Who hasn’t veered gratefully into one of these? Since the neck contains large blood vessels (such as the carotid arteries) close to the skin, neck cooling can enhance your temperature regulation.
Surprisingly, studies have shown that water over the head and neck doesn’t actually lower your core body temperature, the direct physiological pathway to improved performance. Rather, it lowers your “thermal perception” (the technical term is “alliesthesial thermosensitivity”). If you feel better, you run better.
Water soaking does come with risks. It can increase friction and rubbing in apparel, and add weight to soggy socks and shoes. So, be sure to consider the pros and cons.
The Cooling Cap Solution
At the 2016 Rio Olympic Marathon, U.S. runner Galen Rupp wrapped cooling caps around his fluid bottles so that he could obtain both at official aid stations. This strategy helped him to a bronze-medal finish.
You can do essentially the same. Wear a hat, and place a few ice cubes under it while you’re running. The head is a key area for cooling via heat dissipation. Also, as the ice cubes melt, you’ll get a nice stream of cold water down your neck to produce a secondary cooling effect.
Many ultrarunners seem to prefer “bucket hats.” Maybe it’s because they’re lightweight and foldable. Also, the modest 360-degree brim provides a little sun protection, and the hats can be pulled down tight over the head, trapping ice inside.
Studies support the cooling-hat approach. A recent paper in the International Journal of Exercise Science used triathletes as subjects in a crossover design. They ran a 5K time trial with and without “a head-cooling cap.”
Result: The subjects performed significantly better, by 1.2%, in the cooling-cap condition. A longer time trial might have led to even larger differences.
The authors wrote: “Continuously cooling the head may be a practical strategy to enhance running performance in hot conditions.”
The running marketplace has responded with several different cooling hats designed to work with “stash pockets” for ice or frozen-gel sheets. They are easy to find with your favorite search or AI tool. Several good options: here, here, and here.
New Tech From The Omius Headband
A new cooling headband made its global debut in last summer’s Paris Olympic Marathon. Indeed, the female gold medalist, Sifan Hassan, was one of several top runners wearing the Omius headband.
Other Omius users didn’t fare so well, including two-time Olympic champion Eliud Kipchoge, who dropped out. It will be interesting to see if any Western States runners decide to give the Omius band a try-out.
Developed in one of Mexico’s hottest cities, the Omius band supposedly increases the surface area (thereby enhancing evaporative cooling) against the forehead. However, published research has yet to support any performance benefit.
A randomized, crossover trial in the Journal of Thermal Biology6Desroches, A. J., Fedi Aloui, Deshayes, T. A., & Goulet, E. D. B. (2024). Assessment of the OmiusTM cooling headband effectiveness during a 70-min submaximal running effort followed by a 5-km time-trial in hot/humid conditions. Journal of Thermal Biology, 124, 103964–103964. https://doi.org/10.1016/j.jtherbio.2024.103964 found that the Omius device did reduce forehead comfort and temperature during a submaximal effort. However, it did not improve performance in a 5K time trial that followed 70 minutes of submax running.
The authors concluded: “Therefore, the Omius™ headband is unlikely to improve running velocity in the last few kilometers of an endurance event held in hot and humid conditions.”
The Magical Cooling Bandana
The ice bandana has become an almost universal favorite among hot-weather ultrarunners. It’s lightweight, simple, and effective. Basically, a bandana or scarf with several pockets that hold ice.
In this YouTube video, you can see how Megan Roche tied an ice bandanna around her husband David’s neck, and then tucked it into the top of his shirt to keep it from bouncing. Something worked well. On a warm day, David broke the course record in this year’s Quad Rock 50 Mile in Fort Collins, Colorado.
The neck presents a large, exposed area, making it a top spot for cooling applications. Cooling the neck has been shown to reduce heat strain more effectively than cooling the same surface area of the trunk.
A recent review in Sports Medicine-Open7Cao, Y., Lei, T.-H., Wang, F., Yang, B., & Mündel, T. (2022). Head, Face and Neck Cooling as Per-cooling (Cooling During Exercise) Modalities to Improve Exercise Performance in the Heat: A Narrative Review and Practical Applications. Sports Medicine – Open, 8(1). https://doi.org/10.1186/s40798-022-00411-4 found that “wearing a cold neck collar improves time to exhaustion.” A few studies did not show this effect, likely due “to the cooling intensity not being strong enough.”
This proviso applies to many of the strategies listed in this article. That is, ice beats lukewarm water.
You can find a variety of solid ice-bandana picks at the following links: here, here, here, and here.
The Slurry With The Ice On Top
When you want a freezing-cold, crushed-ice drink from your local convenience store, you probably ask for a “slushy” or “slushie.” In sports science, these are called “slurries.”
Same thing. And they can be highly effective at improving performance in the heat, because they deliver an icy drink all the way to your core, where it does the most good. A lower core temperature means your body has more capacity to store the heat you generate by running, and/or to delay heat-induced fatigue.
A recent meta-analysis of randomized controlled trials, “Optimizing Ice Slurry Ingestion for Endurance Performance in the Heat,” concluded that ice slurries provide “a significant benefit for endurance performance in the heat.” Also, athletes appreciated this approach because it is “effective as a performance enhancement in the heat, and also is very practical.”
Ice slurries work both before a race begins and during an event. You don’t have to drink a lot for the slurry to be functional. Ice gets the job done in modest doses because it’s so cold.
The Peppermint Solution
Menthol skin creams, mouth rinses, and mints don’t get discussed much as cooling agents, but they can prove effective. This subject was explored in an “expert-led consensus statement”8Barwood, M. J., Gibson, O. R., Gillis, D. J., Jeffries, O., Morris, N. B., Pearce, J., Ross, M. L., Stevens, C., Rinaldi, K., Kounalakis, S. N., Riera, F., Mündel, T., Waldron, M., & Best, R. (2020). Menthol as an Ergogenic Aid for the Tokyo 2021 Olympic Games: An Expert-Led Consensus Statement Using the Modified Delphi Method. Sports Medicine, 50(10), 1709–1727. https://doi.org/10.1007/s40279-020-01313-9 published prior to the 2020 Tokyo Olympics.
At the time, many were concerned that Tokyo’s high temperatures and humidity would severely impact the marathon and other endurance events. The paper concluded: “Menthol topical application and mouth rinsing are ergogenic in endurance activities.”
A randomized, controlled trial in the European Journal of Nutrition looked at drinking peppermint essential oil in water before or during an endurance performance. It concluded that the pepperminty water “significantly increases the time to exhaustion of recreational runners.”
The Australian Institute of Sport has even recommended that a familiar 160-year-old lozenge named “Fisherman’s Friend” can “aid performance in some circumstances when competing in hot conditions by exerting a cooling sensation.”
Menthol achieves this effect by activating the same nerve receptor that is involved in detecting cold temperatures. Indeed, the receptor is often called “the cold and menthol receptor.”
The Palm Of The Hand Method
If you’re searching for another simple cooling strategy, look no further than the palms of your hands. Grab a couple of ice cubes and run with them until they melt. Studies have shown that the palms are excellent for cooling the body.
The palms have a high density of blood vessels near the skin’s surface. These provide heat loss through convection and conduction. Since the palms have fewer sweat glands relative to other body areas, you don’t disrupt the cooling effect of sweat evaporation.
One paper in the Canadian Journal of Applied Physiology9Hsu, A. R., Hagobian, T. A., Jacobs, K. A., Attallah, H., & Friedlander, A. L. (2005). Effects of Heat Removal Through the Hand on Metabolism and Performance During Cycling Exercise in the Heat. Canadian Journal of Applied Physiology, 30(1), 87–104. https://doi.org/10.1139/h05-107 found that palm cooling could improve time trial performance by 6%. Some companies are now making lightweight gloves with frozen gel inserts that might last longer than cubes.
Final Frontier: Groin Cooling
One other body area holds cooling potential —the groin. Unfortunately, there’s no research on groin cooling. Maybe that’s because it’s difficult to recruit study subjects.
And yet the groin offers a large skin surface with the femoral arteries and veins close below. That makes it a natural choice for body cooling, as noted in many medical articles on heat illness.
For example, here’s what the Mayo Clinic10Mayo Clinic. (2018). Heatstroke: First aid. Mayo Clinic. https://www.mayoclinic.org/first-aid/first-aid-heatstroke/basics/art-20056655 says about treating an athlete with possible heatstroke: “Place ice packs or cool, wet towels on the neck, armpits, and groin.”
Runners could readily drop a few ice cubes into the liner of their running shorts. Sure, the thought makes you squirm.
But somebody’s going to try it, maybe even at Western States, because a winning effort always demands some temporary discomfort.
Putting It All Together
The best way to run cool in hot weather is to combine several of the above strategies. Train for the heat, hydrate sufficiently, pour cold water over your head, use ice bandanas, and so on.
At the same time, be realistic and run smart. On a hot day, no amount of cooling can help you run as strong and fast as you would in better weather.
Always adjust your expectations. Always plan a pace that’s appropriate for the conditions.
