Heat Training (Acclimation)

HeatTraining information and resources:

  • (We will update this lead post with appropriate info over time.)

How to Get Faster with Heat Training

  • While the focus of optimal indoor training is to control two critical variables — intensity and duration — heat is another powerful tool to develop fitness and get faster.

Huh, this is my topic, I guess :). Living in Middle East and having rides around in 40 degrees , I cannot wait to see the responses :slight_smile:


I’ve been using heat training to prepare for Kona as it’s quite cool here in northern Ontario already. I keep my room at 30 Celsius approximately 80% humidity. I started 2 weeks ago and found it excruciating the first time, thinking I’d never be able to keep it up. I kept at it adding 20-30 in the sauna immediately following my workouts and I was able to complete a 4 hour ride last weekend. I’m finding my 1-2 hour rides followed by a brick run to be quite tolerable now. I’m quite surprised how quickly I was able to adapt. I’ve made sure to up my liquid and sodium intake during and after workouts. Looking forward to see if it all pays off in Kona.

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Hi, I’m training for an event in Namibia, 373km MTB through the Namib Desert and starting in 40 degree celsius heat. Extremely warm and dry conditions.

I’ve been doing my low intensity training without a fan and also included sauna sessions to become better heat adapted. There’s a lot of info on the sauna benefits and also how to do the sessions by getting your core temperature up first through exercise and then sitting in a dry sauna for 20 - 40 minutes. For me anything above 20 min is tough.

Now my question is… How do you end these sessions? I find sitting in a pool directly thereafter brings down core temperature quickly and prevents sweating for the next 2 hours as your body keeps on trying to cool down or whatever happens.

Are there positives to naturally getting body temp down to normal vs doing it in a pool directly after sauna? The aim obviously remains to get adapted to heat for a big event.

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A good listen from the Flo guys this week "How to Control your Body Temperature’ with Dr. Douglas Casa:

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Yup, I posted a dedicated thread on it earlier today.

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Ah fair enough :slight_smile: I did a search for ‘heat’ before I posted but it didn’t come up.

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Pretty substantial, and free, review article on different protocols:


Interesting, thank you for posting. It seems like Hot Water Immersion (HWI) would be the most practical and easily accessible method. I’m gonna give that method a try this year.

For sure. I’m not seeing as much data on Hot Water Immersion as the other protocols, but even if gets you 80-90% of the benefits as the rest it still holds true that the most beneficial plan is one you can consistently stick with. I’m definitely looking to do it this year. Last year for my first 70.3 I did some heat acclimation with 2 weeks of low intensity workouts, but forced my body temperature (oral) >101F. It. Was. Miserable. But, subjectively, I feel like it had a substantial impact. The race was in the 80s and I felt amazing on the run.

@chad @Nate_Pearson I wanted to tag you, just for the off-chance you hadn’t seen the above review.

I’m considering doing this in the near future even though my A race isn’t until June with the thought that if I can get the boost now, I should be able to train harder and see further gains. After-all, it could be called legal doping… I need to revisit, but I found a study that stated in conditioned athletes, they may maintain their heat acclimation with just 1 session every 10 days. Any thoughts on this plan?

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Does sitting in a sauna have to be post-workout? Will I get the same benefits if done on a separate day?

Is there a specific time period necessary? 10min, 20min, 60min?

The two studies I’ve seen referenced were: 15 minutes pre workout followed by 15 min post workout, or 30 min post workout. The recent podcast w/ Ms Looney mentioned not drinking water, but I had not heard that part before. Anybody have a reference to that?

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I just listened to this podcast from Sonya Looney, friend fo the TR podcast and user. Great information in this podcast. They break it down and make it easy to apply these techniques. I am definitely going to do this in hope to improving my performance in the humid midwest (KS) during the summer gravel events.

Sonya Looney

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I don’t have a reference and have not read anything either way. The benefit is presumed to be from raising both skin and core body temperature above a critical level and the subsequent volume loss that accompanies. It is unlikely the fluid you’re drinking would be warmer than your core temp and could thus be counterproductive. Could swish and spit for an RPE benefit id imagine

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I’m trying this right now. I’ve started with 2 easy endurance rides (1h and 45 minutes) with heating on and some layers of clothes on me. I’ve also did a short VO2 Max (Mills - 5 => only 30 minutes) and it was very hard - muscles were cool, but I I was feeling the need to make a conscious effort to keep my heart inside my body :slight_smile:

The studies cited here and there are usually 10 days, with 90-100 minutes at ~35 Celcius, which is very hard to do for me, just at the end of Full Triathlon program (3 weeks to go). So here is what I do:

  • shorter rides for now, added to the base plan as I would certainly not be able to complete a tempo ride like Polar Bear in those conditions
  • temperature is way lower - somewhere around 26-28 Celcius is the max I’m getting for now (next week I will be able to put heat earlier, it takes quite some time), but extra clothing seems to do the trick
  • I will aim to do it almost daily, even if it’s for 30 minutes (I have 3 weeks left, so that should add up), with at least 2 longer rides per week

Anybody willing to share experience with their protocol and how it turned out ?

I had my first XCO race in the heat and humidity (~75-80 F) yesterday, previous 2 races were in the 50s F. Well, training in my basement around 62 F and racing in the cool temps certainly affected me not being heat adapted (HA). Race was brutal and RPE was 110%+. I felt horrible to the point I almost didn’t feel like pushing it at the end. Had to constantly fight the demons in my head that were insistent on making me stop.

I also felt really dehydrated during and after the race. In fact the rest of the day I was kinda a mess, possibly with a little heat illness. Definitely going to start my HA training before my next race. I am going with the Hot Water Immersion (HWI) passive protocol 10 days out. Will do 30 minutes in the tub and hot bathroom (heated fan) post TR workouts (mid volume plan). Possibly also doing 30+ minutes of HWI on my rest days (2 days a week). Race is 2 weeks away so I’ll post my results/findings from this HA training on my RPE race effort.

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Interested in how this works for you. “Life” has had me move to the deep south for the summer, and I’ve been here about 12 days. In that time, I’ve done a metric century and two crits. The metric century was about 82+F with some humidity, and it wasn’t bad at all. The crits last night… heat index in excess of 100F. I knew I was in trouble right off the bat. I suffered badly through a short cat 5 race, finishing second but not feeling strong at all, and then followed 10 min later by a 3/4/5 race where I was literally just trying to finish without falling over - it was my first road race where I’ve not at least stayed attached to the main field or front pack, and was such that recovery watts felt hard.

I can sit around and hope that there’s some cloud cover or something or that I’ll adapt better for the last two evening races in that series, but I feel like I need to actively be able to handle the heat better. HWI is an option. Sauna (other than just sitting outside for a while after my morning workouts) isn’t really an option, and I don’t want to sacrfice indoor workouts by overheating the rooms for that adaptation considering I’m racing Cat 5 and mostly concerned with just getting in starts and learning my racing style at this point.

@MI-XC, please let us know how the HWI seems to work for you!

I am following the HWI recommendations of this article:

I’ve done 4 Heat Adaption (HA) sessions so far and today will be my 5th after my Carpathian Peak o/u workout. I am doing HA training only on my work days (5 days a week) and sorta “nothing” on my rest days (see below exception to this rule). Here is the protocol I follow.

  1. I do all workouts above z2 optimized with a cool room and fans. My goal is to keep training performance high, so I don’t want to add another stressor of heat to that equation likely limiting my power output.

    • For z2 rides I workout without fans and don’t take off my shirt/jersey when I get warm. I just sweat it out (towel on/under the bike is now needed). I’ve seen no negative recovery affect and my HR does NOT raise higher than normal.
  2. At the end of of intensity workouts I turn off the fans during the “cool down” spin to maintain internal body heat. After I get off the bike I immediately put on a sweatshirt hoodie and sweatpants, again to maintain internal body temperature as I prepare for the HWI.

  3. HWI:

    • I start running the tub with 109-110 F degree water (tested with kitchen meat thermometer). I add in bath soap/bubbles to retain heat. According to the above article 104.5 is the suggested temperature, but I find the tub tends to cool over time, so I go a little above that to make sure. I test the water coming out of the faucet and at the far end of the tub to ensure the water is within the 105-110 F range. I’ll adjust accordingly until it fills.

    • I have a heater fan in the bathroom which I also turn on until the tub fills, but this is probably not needed. Once the tub fills completely, I take off the sweats and riding gear and get into the tub up to my neck. Tub is usually about 109 F +/-. I set a timer for 30 mins and put on either music, podcast or a YouTube video on my iPad (distractions are very beneficial).

    • Roughly every 4-5 minutes I take the temperature of the tub to ensure it is at or above 105 F, but I’m realizing this is not needed as the bubbles seem to keep the temperature for the full 30 mins. I may start at 110 degrees and by the end it only slips to 107 degrees after 30 mins. However having something to do every 5 mins breaks up the session.

    • With a separate medical thermometer, every 4-5 minutes I take my body temperature (under the tongue) to ensure I’m not over the 101.3 F recommendation. I’ve found that I often creep up to over 102 F, so I raise up out of the tub to my waist to cool off, then take my temperature a couple minutes later. If I’m at the desired temp, I’ll sink back in up to my neck. I’m learning that I can actually tell when I’m starting to get over heated and a quick temp check ensures that.

    • I continue this process for the duration of the 30 minutes of HWI. Additionally I consume a recovery drink, about 1 liter of water/mix during the HWI. I ensure that the drink is warm and not cold, as I don’t want to cool off my internal body temperature. Once the 30 mins is done I hop out into a warm/cool shower and actually bath myself.

    • HA training is not easy especially after a hard workout. In the beginning I was actually dreading the HWI more than the workout. Now that I have my protocol dialed and I know what to expect its not as bad.

Pro Tip: You absolutely need thermometers. The first 2 sessions I only lasted 15-20 minutes of HWI. I thought it was because I wasn’t heat adapted, but then I realized I had the water way too hot (115+ F) and my body temperature also raised to over 103 F :grimacing:. So for success and safety use thermometers.

Yesterday after Pettit with no fans it was not bad at all. I additionally lasted the full 30 mins during my HWI training. My next race is in 9 days and it’s expected to be 80+ degrees with high humidity. I will continue my HA training to see if it has any benefit. However, I can tell already that I’ve gained some mental adaptation of working in the heat.

Extra Credit: I have also introduced “living warm” every day to include rest days. Meaning I am ensuring I’m a little warmer than I’d prefer to be throughout the day. I may put on a little extra clothing during the day at work and keep the AC lower in the car and house. I want to be comfortable, but I also don’t need the AC blasting all day while I’m also going through HA training. The only exception to this is at night when I want to maximize sleep with a cool room.

I’ll update next week with how it’s been going.


I spent about two weeks doing my workouts in my bathroom with the heat cranked to 85* and the shower running early to get some steam in there. I shut it off after 5 mins. I was doing the easy workouts and some sweet spot mostly. Did some v02 work as well. I should have done mostly the easy longer stuff in the bathroom and my vo2 with a fan and whatnot.
Did it work? Sort of.

I live in Central Florida, this time of year temps are often in the mid 90s. Even when temps are lower humidity is very high. At the same pace/RPE as I was working zone 2 a couple months ago, my heart rate is at least 10 bpm higher. Do I dial my effort back even further, or just work at normal pace/RPE?