Acclimate to Summer Heat to Improve Performance in Fall Races

Tired, sweaty and salty after a long, hot, humid run.
Tired, sweaty and salty after a long, hot, humid run.

Most runners loathe running in the heat.  Don’t even talk to us about humidity.  It sucks.  We hate it.  We do everything we can do avoid it.  With very few exceptions, the only runners I know who enjoy the heat are short distance runners (5k and under).  Above that distance, most of us cringe (and complain excessively) when we see a weather forecast with warm summer temps and thick summer humidity.

No doubt that is because the heat and humidity does (with few exceptions) dramatically affect our performance.  When it is warm and humid, our  heart rates spike and our paces plummet.  It is harder to cool down and our hearts have to work overtime to keep even an easy pace.  Nice easy runs suddenly become more challenging.  Long runs can become downright demoralizing.  Even worse, running in the heat and humidity takes a lot more out of you, so it is harder to fully recover and prepare for the next day’s effort.

The obvious solution to this problem is to run very early in the morning, to run late at night, or to hit the treadmill in the a/c. But should we avoid it?

I don’t think so.  While it is tough, getting acclimated to the heat and humidity will make you a stronger runner and will better prepare you for race day.   Yes, it is hard and you do have to make adjustments.  But it may just make your nice cool race day feel like utopia.  Or, if you are unfortunate to be dealt a bad hand on race day, you won’t be a complete wreck, physically or mentally.

From my experience, my very best marathons came on the heels of hot summers.  And I’ve had countless flat Spring marathons after training in the cold.  There is a reason so many seasoned runners repeatedly claim that fall marathon season is always better and faster than the spring season, at least in my opinion.  So I embrace summer running (as much as I can anyway).  To do it though, you need to follow these tips:

1.  Slow down.  No one likes this one, but it takes a lot more effort to run hard and/or long in the heat.  Give yourself permission to slow down a bit.  If you absolutely can’t stand the idea of not meeting your interval or tempo paces, start out doing your warm runs on easy runs.  Just be very careful and realize you need to give yourself more fluid and TLC to recover.  And if you run a recovery run in the heat, you may be defeating the purpose.  Understand it is warm, that acclimation is good and roll with it.  Trust me.

2. Ease into it.  Rome wasn’t built in a day.  Your cardiovascular system and muscles will also not tolerate harsh conditions quickly.  When you are in a cool weather climate (or excruciatingly brutal climate like me) the first days of warm spring or summer can be really hard to handle.  Don’t worry, you’ll get there.  Give it time.

3. Run in the heat for a week or two.  After you have run some in the warm weather, consider running all of your runs during a week or two in the heat.  Run at 10:00 am during vacation.  Or run right after work if you don’t have that luxury.  Try to make it consistently happen though so your body truly gets used to it.  One or 2 runs in the heat over the summer is certainly not going to do it.  The caveat, of course, adjust paces as needed, but I am willing to bet that by the end of the week (or two), the warm run will feel much easier than it did on the first day of the week.

4.  Hydrate, hydrate, hydrate.  We’ve talked about this topic a fair bit around here, but you need to hydrate in the summer to deal with the heat.  Not 30 minutes before your run or during your run.  Make sure you have a glass of water around you at all times.  Drink, refill, repeat.  You’ll be glad you did.

5. Electrolytes are your friend.  More than just water, you need electrolytes to replace all of the salt (and other minerals, such as potassium, chloride and bicarbonate) you are losing in the heat and humidity.  Yup, we’re called Salty Running around here for a reason!  We are known to run hard and have a layer of salt on our arms, legs and face when we finish 20 miles in the heat.  But we also know how to replace and recover.  I personally like nuun tablets, but Gatorade and other sports drinks also do the trick.  I also tend to use gels with electrolytes (I do PowerBar) for longer races.  Everyone today wants to shy away from salt these days, but as distance runners in particular, it is critical.  Nope, this is not license to eat all the salty fries you want (oh how I wish), but do make sure you are getting and replacing enough sodium and electolytes. You also need potassium, so reach for those bananas – they really are runners’ super foods.  They keep potassium levels up, avoid cramps and tolerate the heat better.

6. Run hard workouts in the heat.  Yes, run that tempo run, the hills, the intervals, and probably most importantly, the long run in the heat.  It will likely suck the life out of you, but roll with the punches, shake off the fact that it is slower than you like, and know that it is making you stronger.  No, you don’t want to beat yourself up workout after workout, but you do want your body to acclimate.

7. Be smart.  This is the asterisk.  You want to acclimate, but you don’t want to disregard risk.  If you are overheating (or it feels too hard), stop.  Take a break.  Sometimes we runners think breaks are weak.  Not so when it comes to running in the heat and humidity.  If you feel you need to stop, Stop.  Catch your breath, let your heart rate drop and evaluate where you are.  If you need to slow down or (gasp) cut a work out short, do it.

I believe in acclimating to the heat during training.  We are in the hottest month of the year (in the US anyway), are you ready?  If not, what are you waiting for?  Do you have any heat/humidity tips to share?


Mindi is a serial marathoner. She is a private practice attorney, wife and mom of two awesome (and super fast) boys, ages 12 and 14. She coaches Girls on the Run and is a big advocate of youth running.

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  1. I think it was Mark Hadley who I heard call running in the summer heat and humidity “poor man’s altitude training.” It’s been kind of hard to get acclimated here this summer because it’s hardly been over 80! It’s been the best summer for running I’ve ever experienced!

    1. I like that (poor man’s altitude training)! Yes, this summer has been relatively mild, so we’ve been lucky, but I think we still benefit by running in the warmer temps and humidity (even if only in the 70s, the humidity has been brutal here many mornings) rather than sticking to the indoors.

  2. I agree with you – I think it’s important to run in the heat, as it is to practice through any adverse condition – so you’re ready for anything come race day. I’ll never forget a 5-miler I ran a few years ago on a July evening in 96 degree heat and ridiculous humidity. I was on pace for a great race for the first 3 miles, and then absolutely crashed during the last 2 miles because the heat really got to me. I hadn’t spent time running fast in hot conditions, so I was totally unprepared. Since then I don’t shy away from running quality workouts mid-day in the summer – with some careful hydration both before and after!

  3. Florida. August. 70% humidity, 96 degrees in the shade. So…I wear a long-sleeve spf40 shirt, I got one of those cooling clothes advertised on late night TV, and a few days a week, I move indoors to do pace training on a motorized treadmill.

    1. Florida is brutal. I lived there for 12 years and I have no idea how I was able to run in the summer. Good luck getting through these rough months!

  4. I’ve spent all summer running in 90 degree weather and 100% humidity (flat as a pancake terrain). It’s brutal. But I know it has helped. I went on a vacation to Yellowstone and ran in the cool mountains at an easy pace a full 45 seconds faster than what I do in the heat. I thought the altitude and hills would kill me, but I didn’t even notice. It was way easier than running in crazy, Texas heat.

    1. That is interesting – thanks for chiming in. I’ve run in both conditions and think both are challenging. I am glad to hear your hot weather training allowed you to nail the altitude. You’ll have to run a cool fall race and let us know how you do!

  5. This past June I left muggy, humid and hot Ottawa to run the Vancouver Half. While it was still warm there, it definitely wasn’t hot and there was NO humidity. Honestly I felt like I had grown a third lung!!! I never felt tired and my breathing was so much easier. There is no doubt in my mind that the tough training in Ottawa, combined with the perfect weather in Vancouver contributed to my fastest half time ever – 1:57 and change, almost 6 minutes faster than my previous best!