Adapting to the heat


Hi, last month Prof sent out an email about how heat impacts our workouts. I was wondering how I should take this into account during my training? How should I either adapt the workout or my efforts during the sessions for both running and biking? I cannot hit the same paces in the heat and my heart rate usually increases very easily.

Any thoughts and tips are greatly appreciated!

Great question. The series of emails can be found here for anyone interested. But the answer isn't too difficult. Because the external environment (heat) has changed the context, you simply must rely now on your internal markers of effort — namely HR and feel/effort. That comes back to this earlier email sent out on our latest Garmin push release. So when its hot (or altitude as well), choose HR and feel to guide you, and disregard pace or power. Trust that the adaptations you'll make from the training session will be best if you following the internal markers of stress — following external markers like pace or power can blow you up and that isn't going to be optimal when we look at the big picture. Remember to always think and say to yourself during your session: "the most important training session is the next training session". As our recent athlete of the month Cindy Maloney shows, this consistency over time with appropriate daily load is what drives personal bests.

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I’m not great in the heat, just my genetics.

One of the lessons I learnt from last year is not to avoid the heat in training. I thought I was being smart training in the cool of the very early morning during hot days. But when it came to my main event it was also a heatwave and I was not used to it.

Thus get out in the heat, adjust as necessary, and work out what works for you. I did sweat tests at various temps, humidities and effort levels this year. I found this useful for working out what kind of intake I should be looking at, without exceeding the maximum’s recommended.


Hey @Phil Funny you said not being great in the heat… I am from Finland where 15c is a hot summer day :sweat_smile:
Since 2008 I’ve lived in hot, tropical environments, like Brazil, Dubai, Houston (summer), and I still feel like I struggle. My swedish training partner on the other hand would run with me and barely a sweat drop would be dripping off her, while I was drenched, and close to heat stroke… We had a good laugh, but it made me think there must be somekind of genetic factor. I also truly enjoy training in cold weather, and miss winter, with snow shoveling and all. Never really understood people who move from the cold to heat, snow birds… :stuck_out_tongue_closed_eyes:
If I ever make it to Kona, I better prep for the heat.

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Sweat rate, salt content, and even gastric issues have a genetic component from what I’ve read. I’ve kind of come to the conclusion to avoid main events in August and target events in more northern climbs.

I have never DNF an event when it’s snowed or rained heavily or been blowing a gale as well. But put me out in the heat long enough and it may well lead to me not finishing and prioritising my health by stopping. Just don’t get long enough periods of heat to adapt. Since my events are also very long, even just a tiny shortfall in keeping up with salt and liquid replacement will catch up with me. I also know I’m at the upper end of sweat rates from the tests I’ve done. At 700mL an hour I’m barely keeping pace if it’s hot.

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Good morning Phil, I have the weird knack of enjoying tough weather too. I know I need to get back to winter sports, lol… My first triathlon was 9c, crazy wind and foggy, rainy. Loved it!

I lived in Dubai for 5 years, so I was able to get better at heat, but it is not something I enjoy - likely a bit of a mental issue as well. You can take a girl out of Finland, but never Finland out of a girl. :smiley:

Living in Dubai, I used to think I needed a lot of electrolytes. I never got tested for sweat rate or anything, but I did do my observations (weigh myself before a session and after), calculated how much weight I had lost, and then converted this per hour exercise and think I needed to prevent de-hydration so was prepared to stay ahead of the de-hydration… (my calculations would have me at 1.2L per hour!!!) you know the drill… I also self-diagnosed that since I had salty sweat stains in my training clothes I was a “heavy sweater”. I spent too much money on Precision Hydration as it was the only one on the market that I liked the taste of, and low in sugar.

I would drink on a predetermined schedule. I drank a LOT during my rides and runs in the heat. possible way too much. I’d always swell up, have GI issues, and even feel a bit doozy after a long ride. It was most likely a combo of being reliant on carbs and drinking too much electrolytes as well.

When I started working with @Prof, he asked me to be curious about hydration and drink to thirst. This was mentally hard at first as I was so used to drinking to schedule. Now I only drink water, to thirst, and give my food a bit of extra salt.

There’s a great episode on this with Dr. Noakes and @Prof at the Training Science Podcast… CARBS, FATS, SALTS & BRAINS - with Professor Tim Noakes - HiitScience

and an article that you may find interesting: Are we being drowned in hydration advice? Thirsty for more? | Extreme Physiology & Medicine | Full Text

My point is… stay curious! You may need less than you think.


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Since we have this I will not create a new thread :slight_smile:

The only thing that bothers me is actually race in hot. I plan to buy CORE sensor and start some training/heat adaptation with it before the race.

The problem is I don’t know how to start - I need a guidance like:

  1. when before a race to start
  2. which temperature I should hit in the sessions
  3. how many sessions a week
  4. how long should be the sessions
  5. etc.

Can @Prof guide us like how to start with CORE sensor and how to prepare for hot races? :slight_smile:

Hi @Bart.

There are many many nuances to this question. If you’d like to geek-out in the area, please check out this paper written by one of my PhD students Julia Casadio. Unfortunately I have no experience with CORE and hopefully others can chime in.

Key principles are 1) get hot, 2) be sensible and recognize that heat is stress too and can really ruin your training if you aren’t careful, 3) prioritize training over heat, 4) monitor you adaptations, even by feel (does it feel like I’m adapting to the heat?).

I thought @cindymaloney did a great job with her heat prep for Kona and she might also chime in on some of the things she did.