A Male Cyclist At The Start Of A Race Drinking Cold Water Out Of A Bottle In The Heat

How to Help Your Athletes Avoid Heat Stroke, Exhaustion and Syncope

BY Phil White

A multi-pronged approach to preparing an athlete for hot and humid conditions can help stem the potential dangers of racing in the heat.

As summer temperatures soar into the 90s and beyond in many areas and humidity takes an extra toll, your athletes face an added challenge in their training. And if they’re not used to hot, sticky conditions, racing in them can become downright dangerous. July and Aug. are the peak months for heat events among athletes.

Still, in certain parts of the country, an elevated risk could persist as the mercury continues to stay high or spikes occasionally into early fall. To help mitigate these potentially dangerous settings, let’s explore some proven tactics to help your clients acclimatize before they encounter hot conditions, stay safe, perform well in the heat and cool down effectively.

Approaching Heat Acclimation from Several Angles

Even if one of your athletes is fit, robust, and adept at tackling new challenges, they’re likely to struggle in excessive heat and humidity if they’re not used to it when they travel for an event. This can range from a dip in output all the way to posting a DNF to suffering from heat stroke or a similar incident. The wider the delta between the everyday conditions they’re used to and those they’ll be racing in, the greater the likelihood of one or multiple problems presenting themselves.

So, for example, if a racer lives at a high elevation and temperatures rarely exceed the 80s, encountering triple digits for the first time in Arizona or New Mexico or adding humidity into the mix in a southeastern state will be more difficult than for someone who lives in a similarly hot place.

Several tactics could prove effective in preparing a client for such an environmental challenge. The first is to try and artificially replicate the racing conditions in training. This might involve the old-fashioned but still effective practice of having athletes train in thicker clothing. In Running to the Edge, his book about legendary running coach Bob Larsen, author Matthew Futterman revealed that Larsen’s athletes trained in thick clothing to prepare for the rigors of the marathon at the 2004 Athens Olympics.[1]

During an interview I did for TrainingPeaks with Futterman, he shared that Deena Kastor and Meb Keflezighi didn’t just train hot but also high as they got ready to win their bronze and silver medals:

The studies Larsen looked at showed that the body has similar reactions to running at altitude as it does to running in high humidity. So running at altitude really helped Meb and his other athletes prepare to perform in high heat and humidity in Greece. If they’d only run in high heat and humidity to prepare for it, they wouldn’t have created more red blood cells—they just would’ve gotten used to being hot.[2]

The runner who lives at a high altitude might not know it, but the training they are already doing might well be preparing them for racing in hot and humid conditions. For someone who isn’t at altitude, adding an additional layer during some sessions like Larsen’s group could be helpful. This can lead to extra sweating, so make sure you advocate for more significant fluid and electrolyte consumption (more on this later in the article).

Another way to reduce your athletes’ risk of a heat event during competition is to add hot water into the mix. Not as in drinking it, but rather soaking in it. A group of British exercise physiologists divided 27 participants into three groups. The first followed their regular training with a hot bath (104 degrees Fahrenheit), the second ran on a treadmill for 40 minutes in a room with the thermostat set at 91 degrees, and the third did an hourlong run in 66 degrees (the latter two groups were at around 65% of their VO2 max).[3]

The researchers concluded that the athletes who took a hot bath acclimated better to the heat. Previous studies had shown the efficacy of pairing training with immersion saunas and hot tubs, but not everyone has ready access to these, so this paper demonstrated a more widely applicable method for getting used to being hot. It’s also handy that the participants who benefited from the hot bath didn’t have to alter their existing training, which in this case was a 40-minute steady state run.

If possible, it’d be best for your athletes to combine these midterm preparation tactics with going to their event site a few days before so that they can also acclimate to the actual conditions they’ll be competing in.

Achieving Race Day Readiness for the Heat

One of the biggest keys to ensuring your athletes survive and thrive on a hot, humid race day – or even during a demanding training session in such conditions — is to work with them to devise a solid plan and execute it. A couple of days before are often overlooked but can play an important role.

Kinesiologists from the University of Connecticut found that 17 distance runners who were moderately dehydrated going into a looped trail run were measurably slower and lost more body mass than their well-hydrated peers. The researchers stated, “A small decrement in hydration status impaired physiologic function and performance while trail running in the heat.”[4]

With this in mind, it would be wise for your clients to ensure they’re drinking plenty of water and consuming sufficient sodium in the week leading up to their events. The same goes for race day. Your athletes don’t want to be taking extra pee breaks on the course, but any deficit in fluid levels puts them at a disadvantage and will make staying hydrated harder.

Another tactic to encourage fluid retention is using a supplement containing sodium bicarbonate. A trial conducted at the Korey Stringer Institute demonstrated that rubbing such a cream into their skin 30 to 60 minutes before heat exposure allowed participants to retain more water.

“If I maintain one’s hydration status, that can help to keep blood volume at a higher level, which can then help with sweating, cell function and thermal regulation,” said Dr. Robert Huggins, study co-author and vice president of research and athlete performance and safety at the Korey Stringer Institute.[5]

He also noted that by increasing blood sodium levels, the sodium bicarbonate cream preserved cognitive function and could offset the increase in heart rate and core body temperature caused by a combination of heat and dehydration.

Pre-race cooling is another widely used tactic for helping athletes cope with heat and humidity. Futterman noted that Larsen had Keflezighi and Kastor wear cooling vests “until right before the starter’s pistol fires,” including during the buildup to their medal-winning Olympic marathons.[6]

Internal cooling also seems to be effective. Findings published in Medicine & Science in Sports Exercise indicated that cyclists who drank a cold drink before a time trial lasted almost 12 minutes longer than those who sipped a warm beverage. The authors concluded that “the ingestion of a cold drink before and during exercise in the heat reduced physiological strain (reduced heat accumulation) during exercise, leading to an improved endurance capacity.”[7]

If your clients have access to cold or iced drinks during the race, this might also help them somewhat offset the harmful effects of heat and humidity. Keeping electrolytes topped up is also vital, particularly sodium, as this is the primary mineral depleted by excessive sweating and other increased internal fluid depletion.

Sticking with the plan you devise for mid-race hydration is crucial without going too far and risking the effects of hyponatremia by drinking excessively. Wearing cooling hats, clothing and accessories such as those made by MISSION could reduce your athletes’ perception of heat. Even if more research is needed about its actual physiological impact, it could have a placebo effect by making them feel more comfortable.

Cooling Down During and After an Event

As tracking technology hasn’t fully delivered on its potential for real-time hydration monitoring or heat status, it’s essential that your clients keep tabs on their physical state from a subjective perspective as they race or train in the heat. Of course, they should be conditioned to expect some discomfort, but if this is accompanied by feeling lightheaded, dizzy or nauseous, the old-school approach of toughing it out might become dangerous.

Certainly, no athlete wants to pull out of a race or quit part way through training, but doing so is preferable to developing heat stroke, exhaustion or syncope (fainting).

Share the symptoms of heat illnesses with your athletes in advance and urge them to first back off their pace if necessary and then, if the warning signs don’t decrease or progress further, stop and seek help at an aid or water station. In the event of heat stroke, the Korey Stringer Institute recommends immediate immersion in an ice bath for 30 minutes or, if this isn’t available, getting to “a shaded, cool area and use rotating cold, wet towels to cover as much of the body surface as possible.” Immediate cooling leads to a 100% survival rate for heat stroke victims.[8]

Suppose your client makes it through the race unscathed — which most will — they can still employ similar strategies to cool down. Getting out of the direct sun and into a covered, air-conditioned location will start the cooling process, and if they don’t want to go as far as using an ice bath or cold plunge, a cool shower can be beneficial. Immediately rehydrating with an electrolyte-rich drink and then continuing to consume adequate fluid via water and fruit and vegetables in the hours following the race (with a pinch of added sea salt if the nutrition isn’t salted) should replenish blood volume.

There’s no way to eliminate the physiological impact of training and competing in heat and humidity, but pursuing a strategic approach to preparing, racing and recovering can make all the difference.


[1] Matthew Futterman, Running to the Edge (New York: Doubleday, 2019), 221.

[2] Phil White, “Matthew Futterman Shares the Secrets of Distance Running Guru Bob Larsen,” TrainingPeaks, available online at https://www.trainingpeaks.com/blog/matthew-futterman-shares-the-secrets-of-distance-running-guru-bob-larsen.

[3] Robert D McIntyre et al, “A Comparison of Heat Acclimation by Post-Exercise Hot Water Immersion and Exercise in the Heat,” Journal of Science and Medicine in Sport, May 18, 2021, available online at https://www.jsams.org/article/S1440-2440(21)00133-X/fulltext#%20.

[4] Douglas J Casa et al, “Influence of Hydration on Physiological Function and Performance During Trail Running in the Heat,” Journal of Athletic Training, March/April 2010, available online at https://pubmed.ncbi.nlm.nih.gov/20210618.

[5] “New UCONN Study Shows How PR Lotion Keeps You Hydrated in Heat and Humidity,” Momentous, available online at https://livemomentous.co.uk/blogs/news/new-uconn-study-shows-how-pr-lotion-keeps-you-hydrated-in-heat-and-humidity.

[6] Futterman, Running to the Edge, 1.

[7] Jason KW Lee et al, “Cold Drink Ingestion Improves Exercise Endurance Capacity in the Heat,” Medicine & Science in Sports & Exercise, September 2008, available online at https://journals.lww.com/acsm-msse/Fulltext/2008/09000/Cold_Drink_Ingestion_Improves_Exercise_Endurance.12.aspx.

[8] “Heat Stroke Treatment” Korey Stringer Institute, available online at https://ksi.uconn.edu/emergency-conditions/heat-illnesses/exertional-heat-stroke/heat-stroke-treatment.

With rising temperatures comes an increased risk of physiological issues for athletes racing or training in the heat. Here are some tips for heat illness prevention.

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About Phil White
Phil White is an Emmy-nominated writer and the co-author of The 17 Hour Fast with Dr. Frank Merritt, Waterman 2.0 with Kelly Starrettand Unplugged with Andy Galpin and Brian Mackenzie. Learn more at www.philwhitebooks.com and follow Phil on Instagram @philwhitebooks.

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