How to train for running in the heat
aka when it’s the surface of the sun
Does your easy pace also feel like your race pace every July?
Pinky promise you that you’re not losing fitness.
Heat is a game changer.
Higher temps- whether dry or humid- change how your heart works, how your blood moves, how your muscles receive oxygen, how you cool yourself efficiently, and ultimately, how hard each step or mile feels.
Good news around the corner….
Summer is not about proving your fitness gainz. It’s about expanding your body’s ability to adapt.
Let’s talk about what’s happening inside your internal ecosystem and how to train alongside it instead of against it.
OKAY, WE GET IT, IT’S HOT AF OUT. But, like, why is that shifting your pace?
Heat changes physiology. Before your muscles even begin working, your body is already trying to regulate your temperature. As you run, your core temperature rises, your heart works harder, and blood is redirected toward your skin to help release heat.
In other words, less blood is able to deliver oxygen to your working muscles and your gorgeous heart is compensating and beating faster. So, even if your pace slows, your effort feels the same.. Yet, your HR is still climbing. This called… drum roll.. Cardiovascular drift.
This super cute thing is your body prioritizing survival over speed and performance.
Let me say that again.
Your body is prioritizing SURVIVING!!!
Humidity makes this even more challenging.
Sweat cools us through evaporation. In humid conditions, that evaporation slows dramatically, so sweat simply sits on the skin instead of carrying heat away. Your body's primary cooling system becomes much less effective.
In dry climates, sweat evaporates quickly, which feels better, but it can also hide just how much fluid you're losing, making dehydration easier to miss.
Either way, your body is working overtime, it being hotter and harder? It's not in your head.
How do you acclimate and support yourself?
Here's the beautiful part. Heat acclimation generally takes about 10–14 days, with most adaptations occurring by day 21.
Here's what typically happens:
Days 1–4
Everything feels harder.
Heart rate is elevated.
Pace slows.
Perceived effort skyrockets.
Days 5–10
You begin sweating earlier.
Blood plasma volume increases.
Your heart doesn't have to work quite as hard.
Runs begin feeling slightly more manageable.
Days 10–14
Most of the major adaptations occur.
Around Day 21
You're close to fully acclimated.
This is one reason many coaches recommend arriving for a hot-weather, cold-weather, or shift in altitude race either: within 48–72 hours of race day, or about three weeks beforehand.
One of the coolest adaptations? (Pun intended.)
Heat training increases your blood plasma volume, which means:
improved cooling
better endurance
lower heart rate at the same effort
greater cardiovascular efficiency
Heat isn't just making training harder. It's creating another adaptation.
And, then, because women are not small men…
Most research in exercise science has historically been done on men (insert huge eyeroll), but we're “learning” more every year about how women's physiology changes our experience in the heat.
Generally speaking:
Women tend to sweat less than men despite having a similar number of sweat glands, making evaporative cooling less efficient.
We naturally have a higher body fat percentage (PS. WE NEED THIS FOR HEALTHY HORMONE PRODUCTION, REPRODUCTIVE HEALTH, AND OVERALL WELLBEING, I WON’T SOAPBOX ON HOW THE LOW FAT BS WAS MADE TO MAKE WOMEN SMALLER EMOTIONALLY, PHYSICALLY ETC. YAY AVOCADO TOAS!) Body fat also provides insulation, meaning heat leaves the body more slowly.
We typically have smaller heart chambers (even with the most beautiful of hearts!), meaning each heartbeat pumps slightly less blood, so circulating blood for both cooling and exercise becomes a little more demanding.
We are not weaker. Different. And, our training can reflect that.
The Menstruating/AFAB/Women POV:
During the second half of the menstrual cycle (the luteal phase), rising progesterone increases resting core body temperature by roughly 0.5°F (0.3°C).
That may not sound like much, but when you're already exercising in 90-degree weather (especially here in Florida with humidity) we know that SH!T matters. Because of this, you may notice:
Feeling hotter when training or running
Increased perceived effort
Night sweats
Greater thirst
Slower recovery
If you're in perimenopause or menopause, fluctuating and declining estrogen can make heat feel even more intense, as estrogen helps blood vessels dilate so more blood reaches the skin and releases heat.
When estrogen declines:
Hot flashes may be more common
Heat tolerance decreases
Cooling is even less efficient
Swelling in the lower body (feet and ankles) may increase
The TLDR? Heat is a physiological stressor for everyone. Hormonal fluctuations simply change how that stress feels and how efficiently our bodies respond.
So, girl...
Chiiiiiiillllll.
We're already asking our bodies to do a lot. Let's stop asking them why they're struggling while simultaneously making them survive a sauna.
Let’s talk about how heat is training. Heat as a stressor is not unlike shifting into altitude. This is your season to attract effort based training over chasing a pace. Here’s how you can run by Rate of Perceived Exertion (RPE).
Easy= able to hold a conversation
Moderate= able to speak in short sentences
Hard= only a few words at a time
We can expect the pace to naturally slow as the temps rise. General, loose guidelines for those refreshing the weather app like Jim Cantore is standing over you.
75°F - 5-10 seconds slower per mile
80°F - 10-20 seconds slower
85°F - 29-45 seconds slower
90°F + - run by effort
Okay, repeat after me, heat is training.
You’re training your aerobic system.
You’re training your thermoregulatory system.
You’re training your central nervous system.
Your six mile run in July may place a greater recovery and resourcing demand on your body than your six mile run in January even if you’ve slowed your pace.
This is why you may need more recovery than your pace alone would suggest. SLEEP.
RED FLAG WARNING SIGNS!!! Aka, swipe left. Do not pass go. Do not collect $200.
Stop immediately if/when you experience:
Chills
Goosebumps
Dizziness
Confusion
Ongoing nausea
Inability to sweat
Loss of coordination
If your urine is dark(er) and/or cloudy
Increase hydration of electrolytes!
Let’s chat recovery. First, stop guessing with hydration and second, you need more than simply water (but also, please make sure you’re drinking tons of that, too!)
You can replace what your body loses through sweat by calculating your sweat loss. (TW for disordered eating and/or other manifestations- scroll about 3 inches to the word GODDESS).
Weigh yourself before your run (minimal clothing, after using the bathroom).
Run for about an hour in conditions similar to your race or training.
Avoid drinking during the test if possible.
Towel off and weigh yourself afterward.
The difference is approximately how much fluid you lost.
From there, you can create a hydration strategy based on your body, not a Runstagram reel.
And sodium?
It's not one-size-fits-all.
Some runners lose very little sodium. Others lose a tremendous amount. More electrolytes are not automatically better.
Alignment beats excess.
GODDESS! If weighing yourself isn't your thing, here's my general framework.
Before
* A full glass of water.
* A serving of electrolytes.
During
Less than 60 minutes
* Water as needed.
* Electrolytes if conditions are especially hot.
60–90 minutes
* 30–40 grams of carbohydrate per hour.
* Electrolytes.
90+ minutes
* 40–60 grams of carbohydrate per hour.
* Break fueling into roughly every 20 minutes.
* Continue fluids and sodium based on your sweat rate.
After
Within 45 minutes:
* Eat a balanced meal or snack with carbohydrates and protein.
* Continue replacing fluids.
* Don't stop hydrating just because your watch stopped.
Fuel more than you think.
Heat increases carbohydrate use. So, if your long run you typically ingest 40g/hour, you may feel significantly better at 50-60 g/hour. EAT THE FOOD.
Many runners assume they're undertrained. Nah, it’s simpler. We’re underfueled.
If your body feels unusually heavy, sluggish, or fatigued during summer training, increasing carbohydrate intake before and during runs is often more effective than simply drinking more water.
Reach for fruit (anyone else drooling over the fresh pineapple and watermelon? And ps, sprinkle some salt and you have some DELISH HOMEMADE ELECTROLYTES)
Eat enough.
Don't fear sugar around training.
Your muscles and uterus love it.
How to structure heat training safely
Run during the coolest part of the day whenever possible.
Seek shaded routes.
Slow your pace.
Shorten runs when your body tells you to.
Walk when needed.
Prioritize fueling before, during, and after.
Include electrolytes, not just water.
Strength train consistently.
Sleep as much as you can.
Respect recovery days.
One of my favorite reminders: You don't gain fitness in one run. You don't lose it in one run either.Planned six miles.Finished three.
Good.
You listened.
That's aligned training and conscious body connection.
Common mistakes runners make
After polling athletes I coach and runners in several online communities, these themes came up again and again:
Training mindset
* Pace does not define fitness.
* Missing a workout doesn't erase months of consistency.
* Vacation is part of a healthy training cycle.
* Flexibility beats perfection.
* Running at unconventional hours is often the smartest choice during summer.
Heat & hydration
* Hydrate before you're thirsty.
* Electrolytes matter.
* Heat tolerance often changes with age.
* Listen to your body instead of forcing the plan.
Fuel & recovery
* Yesterday's nutrition affects today's run.
* Alcohol, travel, and poor sleep compound heat stress.
* Recovery deserves as much attention as training.
Injury prevention
* Strength training protects runners.
* More mileage isn't always better.
Summer safety
* Wear sunscreen.
* Avoid blacktop and all-weather tracks during peak heat.
* Choose shade whenever possible.
* Tell someone where you're running if conditions are extreme.
Some of my favorite ways to cool down:
Legs up the wall.
Water over wrists or behind the neck.
Cool shower.
Lavender towel behind the neck.
A nourishing meal.
Continue sipping fluids throughout the afternoon.
Give yourself permission to rest.
PERMISSION SLIP TO RUN ON THE TREADMILL, TOO!!!!
Closing Thoughts:
One of my favorite things about summer training?
Autumn.
Every year runners tell me, "I suddenly got faster."
Usually, they didn't.
They simply stopped carrying the extra physiological stress that summer demanded.
Summer running isn't a season to prove your toughness. It's a season to practice responsiveness. The runners who adapt, not the ones who fight the weather, are usually the ones who arrive in the fall healthy, confident, and stronger than they realize.
P.S. Here’s some guidance from RRCA on hot weather running.
Personal opinion: This is also why I don't teach hot yoga.
Our bodies already spend enough of the summer managing thermal stress. For me, I'd rather use yoga as an opportunity to down-regulate the nervous system, improve mobility, and recover, not add another heat stressor.
That's my approach, and it's one of the reasons I love teaching in a cooler room.
