21 Tips to Running In The Heat (2024)

Running in the heat

Whenever you’re running in the heat such as competing in the Hawaii Ironman, you need to be smart to optimize your chances of success. Heat is always a major challenge and forces you to adopt a slower pace than when it’s cooler out. So whether you’re training for a 5K or a bucket list marathon, read on.

It’s important to know how your body will react to extremely hot weather and blistering heat. With the proper preparation, you can learn how to get used to running in the heat. You’ll be able to run hard while others are reduced to walking. I find that being prepared for the heat is most important when running a marathon such as the Boston Marathon or events such as an Ironman triathlon.

First, we’ll learn about heat acclimatization and thermoregulation. Then we’ll go over a few tips to allow our bodies the ability to adapt to hot weather appropriately.

What is Heat Acclimatization?

There are benefits to running in the heat. Your body will become stronger due to the increased pressure put on it. However, you can’t just go and run in hot conditions and expect everything to be great.

Running fast in the heat requires heat acclimation, which is a process of slowly exposing your body to hotter temperatures over the course of two to three weeks (according to some experts). Personally, I feel that it takes much longer for your body to adapt efficiently and to develop the mental confidence required to race in really hot environments.

Humidity versus Dry heat

Hawaii has humidity. Arizona has dry heat. Cooling the body includes the evaporation of sweat on your skin. In a humid environment, you won’t have the benefit of cooling down via sweating. Thermoregulation will be more difficult. Also, sweat is warm, so you’ll be covered in warm fluids when you want to cool down.

In dry heat, your sweat evaporates very quickly and it can be difficult to realize how much fluid you’ve lost.

Heat Exhaustion

Heat exhaustion is a condition that can occur when you are exposed to high temperatures and your body is unable to cool itself down. Symptoms of heat exhaustion include:

  • feeling faint or dizzy
  • nausea or vomiting
  • headache
  • increased heart rate
  • increased sweating

If you think you or someone else may be suffering from heat exhaustion, it is important to seek medical help immediately. Heat exhaustion can lead to more serious conditions such as heat stroke, which can be life-threatening.

Heat Stroke

This is a condition caused by your body overheating, usually as a result of prolonged exposure to high temperatures or physical exertion in hot weather and humid conditions. This can lead to a range of symptoms, including:

  • confusion
  • loss of consciousness
  • seizures.

If not caught quickly, heat stroke can be fatal.

There are two types of heat stroke – classical and exertional. Classical heat stroke usually affects the elderly or very young, and those with chronic medical conditions. Exertional heat stroke usually affects healthy adults who are involved in strenuous physical activity in hot weather.

Heat stroke can be prevented by staying cool and hydrated to minimize fluid loss in hot weather. If you must exercise in hot weather, do it during the cooler parts of the day to acclimate slowly over time. Make sure you always drink plenty of fluids such as a sports drink.

Heat stroke is a medical emergency and should be treated as soon as possible. Seek emergency medical treatment immediately if you or someone you know appears to be suffering from heat stroke.


This information within this article is based on my own experience and is not meant to replace your common sense. I’m not a medical professional and I don’t know your body makeup, so please do your own research when playing in the heat.

After heat acclimation, you will be better able to tolerate running in hot weather. However, there are still some things you can do to stay cool during runs. We’ve compiled a few tips below.

Thermoregulation – Cliff Notes Version

Our body has a built-in way of trying to prevent heat exhaustion and heat stroke. When we sweat in response to hot conditions, that is referred to as thermoregulation.

Thermoregulation is the ability of the human body to maintain its internal temperature (core temperature) within a relatively narrow range. This is accomplished by a variety of mechanisms, including sweating, vasodilation, and panting. Basically, it’s what keeps us alive since too much heat can be lethal. Keeping our body cool is good.

The thermoregulatory center is located in the hypothalamus, and it consists of two regions: the preoptic region and the anterior hypothalamic region. The preoptic region is responsible for regulating body temperature in response to changes in environmental temperature, and the anterior hypothalamic region is responsible for regulating body temperature in response to changes in internal heat production.

The thermoregulatory center is sensitive to changes in the body’s temperature, and it responds by adjusting the level of activity of the various thermoregulatory mechanisms. Sweating is the most important thermoregulatory mechanism in humans, and it is controlled by the sympathetic nervous system. Vasodilation and panting are less important thermoregulatory mechanisms, and they are controlled by the parasympathetic nervous system.

The core temperature is the temperature of the internal organs, and it is maintained at a constant level by the thermoregulatory center.

What does all this mean? It says that your brain knows when to react to hot environments and cool itself down. The good news is that we can adapt and with the help of our brains, we can survive and be successful in hot weather.

When Can Make The Heat Feel Worse Than It Really Is?

Before we begin going over a plan to deal with the heat, it’s helpful to know that some factors that we control can make the heat feel worse than it really is. It’s important to avoid these like the plague if you want to do well.

Coming From Cooler Temperatures to a Hot Environment

icy lighthouse

This is always a dangerous situation. It is not uncommon for athletes or runners who live in cooler temperatures to travel to locations with hot weather to compete in races. This can present a problem if the body is not acclimated to the heat of the race environment and it may have difficulty regulating its temperature.

You can be training in 80-degree heat for six months, but if the race is in 90-degree heat, your body won’t be ready for it. It will wear you down, which is why the Kona Ironman always surprises people. The weather says 85 degrees, but the radiant heat from all the surrounding lava rock puts the real temperature well over 100 degrees. That heat index and humidity are a dangerous combination and they overwhelm even the fittest athletes.

I’d compare this to taking an ice bath at home and then immediately running in 90-degree heat. The shock will be amplified for your body.

Lack of Sleep

lack of sleep

A University of Washington study has shown that sleep deprivation alters (hurts) thermoregulatory responses. The results showed that (in both hot and cold temperatures) the body began to lose its ability to accurately control its core temperature after a single night of sleep deprivation.

In other words, if you’re tired, heat will feel hotter than it should. Your body’s own cooling mechanisms may be sluggish in their responses. Remember that you probably won’t get a lot of sleep the night before the race, so if your body isn’t overly rested before that, it will be evident during the race.

Note – it’s harder to sleep comfortably and soundly if you have an injury. So make sure you have the best running shoes and the best running insoles for your body so you stay healthy.

Too Much Caffeine

too much caffeine

I personally have found this out the hard way. I got into the habit of drinking too much caffeine leading up to Ironman Florida one year. I thought I had prepared well, but work had been stressful and my caffeine intake had become higher than normal so I could function with less sleep.

Over a few months, my normal routine was to rely on coffee instead of proper sleep. I was not truly well-rested on race day, and my body let me know. It was hot, and I was toast.

Going through this forced me to dial back the caffeine and to begin to pay closer attention to the total hours slept and the quality of my sleep, rather than how I felt after my morning coffee.


dehydrated dirt

This one is simple. If you’re dehydrated, your body is already compromised and won’t be able to do any of its normal functions (such as thermoregulation) well. Never enter a race dehydrated.

21 Tips – How to Stay Cool When Running In the Heat

Ok, So we know how bad heat is for our performance, and how it can be deadly in some conditions. Let’s concentrate on the recipe to acclimate and some secrets to being comfortable with racing in the heat.

dog sleeping on pile of ice

The heat is always a major challenge to any athlete. Some people perform better than others in hot conditions and this is almost always due to them knowing these little secrets.

If you’re trying to qualify to race in the Kona Ironman World Championships, you’ll definitely want to keep reading. These tips will be crucial to your overall race experience.

3 Months Out

With the right build-up, you can acclimatize to the heat much more efficiently and in less time.

1) Train In the Heat Sporadically

workout calendar

Treat the heat as a workout itself, because it does stress the body on its own. Resist the urge to go in and start training every day in the hottest conditions possible. It’s like going to the gym and lifting heavy every day. You have to have recovery days. Instead, try to prepare both physically and mentally for every hot workout so your body can handle and adapt appropriately.

Use easier days in between the hot workouts to recover and be ready for the next adaption. Easier days don’t mean 68 degrees in the air conditioning, but maybe a bike workout inside without the fan on. It won’t always be easy, just easier.

2) Dry Sauna Training

dry sauna
Does your gym have a sauna you can use? It can help with acclimatization.

I have always seen this produce good results and the procedure is pretty simple. After your workout, go sit in a dry sauna for 30 minutes. The heat will be tough on you as you’re already warm from your workout, but you only have to sit in this environment so it’s bearable.

I have heard from many athletes who have had tremendous performances in scorching conditions that they have used this in their build-up routine. Check out the difference between a steam room vs a sauna. We’ve also compiled the best infrared sauna list for home use.

One study found that athletes who used this approach had a 32% increase in time to exhaustion! The extreme heat forces an increase in blood plasma levels which greatly improves an athlete’s thermoregulation abilities. Try it a few times per week and see if it helps you.

One interesting product that I have tested is the HigherDOSE Infrared Sauna Blanket. It’s $699 and allows you to get a dry sauna-like solution at home. It is a great solution to raise your core temperature to practice heat acclimation at home.

3) Get a Sweat Test Done

sweating profusely

Running well in the heat is directly proportionate to how well you keep your electrolytes balanced. A sweat test can help you get your nutrition dialed in so this is not an issue.

I have done multiple sweat tests to nail my hydration needs on race day. Each one was done differently, but they have all come to roughly the same conclusion – my sweat is fairly salty. This means I have to replenish the salt at a certain dose in addition to the other electrolytes I consume with water. I can say with experience that if you keep your hydration dialed in, your ability to withstand the heat is greatly better.

Here are some of the sweat tests I have used:

Nix Hydration Biosensor – $129 initially. $6.50 per test After
Nix Biosensor

The newest and most high-tech solution is the Nix Biosensor. Put one of these guys on your arm and it continuously measures your sweat throughout a workout and transmits the readings (every second) to an app on your phone.

It tells you when to drink and how much to drink and so on. Afterward, you can analyze your sweat rate to get a better understanding of your personal sodium loss rate.

The downside to this is the patches – they cost like $6.50 each. So it may not be economically feasible to use these during every workout.

LEVELEN – $189
Levelen sweat test patch

They’ll send you a sweat test kit and you wear a patch on your arm for an hour during a hard workout. The patch soaks up your sweat and after an hour you put it in a container and mail it back to LEVELEN. A few days later you’ll receive your personal sweat analysis report which includes the LEVELEN products to use based on your sweat rate.

D3 Multisport Race Day Fueling Test – $200

This one is less technical, but the results were similar. You weigh yourself naked, then work out for an hour without drinking or eating anything, then weigh yourself naked again. The purpose is to see how much water weight you lose in an hour. Nick Suffredin is the contact person and he’s worked at the human performance laboratory at the Gatorade Science Institute. He knows his stuff.

You’ll get a detailed report that outlines what you should ingest during the race to keep your electrolyte and caloric levels in a good place. It’s extremely useful and you’ll become a better athlete with the information you get in the report.

Gx Sweat Patch – $25 for 2 tests
Gatorade sweat test

Gatorade makes at-home sweat tests that can help you better understand your sweat rate and composition. You wear a patch that fills up with sweat during your workout (takes about 25 minutes), and then you scan the patch with the Gatorade app. Voila! You see the composition makeup of your sweat. The app keeps a log of your results so you can compare readings over time.

The app will recommend Gatorade products that match your sweat rate. I found the results to be fairly similar to my more expensive sweat test from LEVELEN. However, many users have complained that the results varied too widely to be accurate. I think this technology is still evolving and will only get better. If you test out this method, I’d recommend doing multiple tests (perhaps one per week) to see a trend line to get your overall sweat makeup.

2 Weeks Out

At this point, you should have the majority of the heat training completed. These last two weeks are when you can really fine-tune your readiness for race day.

4) Arrive Two Weeks in Advance at the Race Location

Airplane at gate

Arriving early does a few things. It helps you rest up from any jet lag and allows you to recon the actual race course without other last-minute pressures. Most importantly, it gets you in the race heat that you’ve been preparing for. Being immersed in the environment and overall air temperature that you’ll race in is great for your mental confidence.

Race day heat acclimatization can take two to four weeks, but since we’ve been preparing efficiently, we should be ready much sooner. During this time it is important to drink plenty of fluids and avoid dehydration. Many people may not have the option to arrive two weeks early but give yourself as much time as possible within your circumstances.

I don’t start counting my race site heat acclimatization days until I’m over any jetlag. This means if I travel from the USA to Europe on Tuesday, I don’t really begin my heat prep until Friday when I’m back to pseudo-normal. My body gets too beat up from jetlag and I need to compensate for that.

Recall how sleep can affect thermoregulation, so be sure you are completely rested before you begin your true acclimatization routine at the race venue.

5) Plenty of Sleep

Get plenty of sleep

I always try to maximize my hours slept and the quality of my sleep during these last two weeks. I will often take a nap in the middle of the day whenever possible. I make a habit of bringing a firm pillow with me (or purchasing a new one from a local Target) so I can sleep like I do at home. Nothing will stop me from maximizing my sleep quality and creating a stress-free environment. Sleep is probably more important than any last-minute training I try to squeeze in during these last two weeks for me.

6) Avoid Caffeine

girl hiding under covers

This one is difficult but minimize all caffeine intake. Overall it helps with my sleep and I also feel like it’s a “mini-detox”. I tend to ingest a near-toxic amount on race day though.

7) Always Carry Water With You

You’ll want to hydrate well to avoid muscle cramps on race day. That means wherever you go, carry a water bottle so you can sip on it. Don’t rely on finding one when you’re out.

Race Day

Your big day is here. We’ve compiled our favorite methods to stay cool on this awesome day!

8) Take a Poop

dog pooping

We all do it, but it’s worth talking about. You’ll do better in hot conditions if your colon is completely empty. Why is this?

Fecal matter requires your intestines to store water in the muscles surrounding your intestines so they can function. Your intestines are basically robbing the rest of your body of precious fluids that it will need later in the day during the heat. This fluid will need to be used for cooling purposes.

Plus, during a race, you’re almost guaranteed to have GI issues if you try to run when your gut is full. That is never fun.

So rid your body of that extra weight in the morning and you’ll be much happier. Take multiple toilet breaks before the start of the race as part of your normal race-day preparation.

Also, poop shivers are a real thing. When you have a large bowel movement, you stimulate the vagus nerve. When it’s stimulated, it can give you chills and lower your blood pressure. Seriously, I can’t make this up.

9) Sunscreen


Sunscreen does more than just protect our skin against skin cancer. A study done in 2019 found that wearing sunscreen helps protect blood vessel functions (things that are critical to thermoregulation). The study found that people who did not wear sunscreen had a decrease in nitric oxide, which is the compound that helps your blood vessels to dilate. When your blood vessels can’t dilate easily, your body has less ability to regulate your body temperature.

Sunscreen can also prevent your skin from warming due to the sun. Since UV rays are repelled with sunscreen, some participants have reported feeling cooler when compared to when they don’t use sunscreen.

So lather up and stay cool.

10) Clothing

man running

You’ve heard this before but wear loose, light-colored clothing. You want your body to be able to breathe.

When sweat evaporates on your skin, you naturally feel cooler. This is why we want loose-fitting clothing which allows the wind to contact our skin. What about primarily tight-fitting triathlon gear? Just make sure the cloth material allows for your sweat to be wicked away from your skin. It will have a similar effect.

11) Keep Your Shoulders Covered

triathletes running in covered sleeves

Your shoulders take a beating from the sun. Wearing a tank top might feel great, but in a long race, it will do more harm than good. Triathlon clothing used to be sleeveless, but in the last few years, companies have found that athletes race stronger for longer when their shoulders are covered. It simply keeps you from taking in too much heat from the sun and slowing down.

So whatever clothing you choose to wear, make sure it has sleeves on it.

12) Adjust Your Effort

adjust your pace

A large study performed on marathon runners discovered runners slow down in weather above 60 degrees Fahrenheit. For every 1 degree above 60 degrees, runners tend to slow by 4 seconds per mile. That means at 90 degrees, you will be running 2 minutes per mile slower than at 60 degrees. That is substantial and most people fail to accept this. Their ego gets in the way and they try to maintain a pace that is not sustainable. They end up overheating halfway through the run.

So revise your pace expectations to still be running at the end of the race. Check your pacing chart here.

Make it a game by keeping your heart rate under a certain ceiling. If you normally run at 150 beats a minute, try to stay under 140, regardless of pace. If you know your heart rate zones, perhaps drop down one zone when it’s super hot. Heart rate is more variable in the heat, but it will force you to run a bit slower than you normally would.

Test out surviving the heat in one of the best marathons in the US.

13) Hydration and Electrolytes


You should absolutely have this figured out and dialed in before race day. But stay on top of it. You need to know what sports drink you’ll get your electrolytes from and also what percentage of pure water works for you.

Be diligent, but also realize that small temperature changes can change your fluid needs. Adapt when necessary, but refrain from making too many changes in a race.

14) Food

Hard food requires more body water to go to your stomach muscles to digest. Liquids are often easier to take when fatigued and the nutrients/sugars get into your bloodstream quicker. This should all be dialed in before race day, but be aware of it in case you feel tempted to grab something new at an aid station.

15) Keep Your Ears Clear of Obstructions

This one is super important and will help a lot

Heat escapes out of your ears. If you have headphones jammed in there, the heat will just build up. It’s like closing all the windows in a warm room when opening them would easily lower the temperature. Don’t clog the natural cooling mechanism that your body uses. I cannot stress this enough – keep your ears clear to stay cooler.


I race faster with music, as do many other people, so I run with Shokz headphones. These are bone-conducting headphones that sound great and do not go into or cover the ear at all. They’re also safer since you can hear things happening around you like a car approaching or another race participant. Use these and you’ll never go back.

16) Sunglasses

woman runner wearing sunglasses

Most athletes already wear sunglasses to reduce glare and improve vision. They will also indirectly keep you cooler. How is that? When you’re squinting to see, you’re elevating your stress level, albeit slightly. This small stressor can be amplified later in a race when small problems often seem larger. Stress hurts your body’s ability to function smoothly and can hurt the body’s ability to regulate heat.

So wear sunglasses. Stay relaxed. Win the race.

17) Wear a Hat

wear a hat in the heat

Running hats can help to protect your head and face from the sun’s harmful UV rays. A hat is also a great place to put ice under and let it melt on your head while you run. Many runners grab ice at the aid stations and fill their hats with some to stay cool. It’s helpful and effective.

Also, hats help to prevent sweat from dripping into your eyes, which can sting and cause irritation. Just make sure you try it out beforehand. Get one that is extremely lightweight and doesn’t give you a headache from gripping your head too tight.

18) Keep Ice in Your Hand

ice cubes

A very wise coach told me once during the Hawaii Ironman to grab ice at every aid station and just hold it while running. Holding the ice helps cool the body quicker since your hand/wrist area is a pulse point, Holding onto it will make your hand cold, but that lower temperature will be carried to other parts of the body also. It’s not an absolute cure for the heat, but it is effective.

Use this technique before you get hot. Once you’re feeling the heat, it can be difficult to recover.

Products that help you stay cool

All the preparation in the world doesn’t prevent the heat from making your day miserable. Experiment with different products to see what helps you run faster in the heat. Below are some that might work.

19) Cooling towels

cooling towels

I’ve used these with varying success. They don’t really get as cold as I want them to, but they seem to be slightly cooler. They also help by blocking the sun from hitting your neck.

I tend to wrap them around my neck so I look like Rocky Balboa after a sparring match. You have to keep them moist to work, so I douse them with freezing water at every aid station.

Be sure to pick one that is larger than a hand towel so each end hangs down in front of you a bit. You can tuck them into your jersey if that helps. Frogg Toggs makes a decent one.

I tend to start a lot of Ironman triathlon run portions with one around my neck but it gets bothersome by about the halfway point and I ditch it. But it does seem to help while I’m wearing it.

20) Omius Headband

The Omius headband won the Best Materials Innovation Award from Triathlete magazine in 2020. It’s only a few years old but many professional triathletes have been seen wearing these in the biggest races.

Omius headband
Omius headband

The science behind the product is interesting. It increases the surface area of the forehead so the evaporation of water against your skin happens easier and you get cooler quicker. Your body heat will pass from your forehead to the small stones on the headband. You have to keep the stones wet (by throwing water on them at the aid stations), and when the wind hits them the water is evaporated and you feel colder. Boom! Science!

I have one of these, and it looks a bit odd, but it seems to work. I’ll wear it in the big races when survival trumps vanity.

21) Core Sensor – Measure Your Core Body Temperature

CORE Body Temperature Monitor

This is relatively new and potentially game-changing. The CORE body temperature monitor allows you to view your internal core temperature during your workout. It is a small square monitor that sits on a heart rate monitor chest strap. It also comes with adhesive strips if you want to attach it directly to your skin, and you can purchase an arm strap as well. I think most users opt for the chest strap though since those are fairly common.

Read our full review of the CORE body temperature monitor.

CORE Body Temperature Monitor

I raced with one of these in the Ironman Gulf Coast 70.3 in Florida this year and it was great. I knew from training that when my core body temperature went above 101 degrees Fahrenheit, I needed to slow down. When it stays above my limit too much, I tend to overheat.

During my race, I could view my core temperature on my Garmin watch for the entire race. When it was climbing during the run, I backed off ever so slightly until it lowered. I could literally see my cooling techniques impact my core temperature in real time. I was able to keep running and avoid overheating.

This monitor takes the guesswork out of things, which helps my mind relax a bit.

CORE is based in Switzerland, and the monitor is being used by Ironman World Champions and ProTour cycling teams. Those guys probably know something, so go get one.


Please, please, please be careful in the heat. It has taken down the strongest athletes in the world and it is unapologetically ruthless. Always have respect for any hot condition, and take small steps when preparing your heat acclimatization plan. Even with little steps, a bunch of them becomes a lot.

Remember, no product can help you race well in hot conditions if you’re not properly acclimated and well-rested. Plan your race preparation accordingly and you will optimize your chances of running well in the heat while others fall apart!

The core of surviving in the heat is fitness. So don’t miss the article about the best winter endurance sports to improve your fitness so you have your best season ever!

Good luck!

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Some of the links in this article may be affiliate links, which can provide compensation to me at no cost to you if you decide to purchase the product. This site is not intended to provide medical advice and you should always consult with a physician before beginning any physical activity.

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