torsdag 14 september 2023

My Heat Training Protocol

Detta inlägg är på uppdrag av CORE Body Temp, som eftersökte folk som använder värmeträning som en del av sin vanliga träning och som kan visa exempel på hur man lätt kan inkludera värmeträning i sin vardagliga träning. Inlägget är inte på något sett sponsrat av CORE Body Temp eller har något samarbete med dem, utan har skrivits på eget bevåg med egna åsikter och upplevelser. Inlägget är på engelska. Hoppas ändå ni kan få nytta av inlägget, och tveka inte om ni är intresserade av att implementera värmeträning och vill ha hjälp och tips! Kontakta mig då på



As many of you might know, something called "heat training" is taking the endurance sport world by storm at the moment and is one of the most interesting things in sport science right now. Core Body Temp is the leading company and are working with the top triathletes and World Tour cycling teams to help them measure and understand the human physiology. But it's not only the professional athletes that are benefitting from doing a heat training protocol. Even amateur athletes are now using it to boost their performance, including me. I've used the Core Body Temp sensor and have been doing heat training continuously  for the last 3-4 years. But if I'm beeing honest it's only for the last year or so I've gone all in and done it more strict with a heat training protocol that I actually follow to the letter and measure Core and Heat Strain Index more carefully.

About me:

I am a 25 year old swedish elite mountainbiker that focuses on Cross Country Marathon and Olympic diciplines. This year I did Nove Mesto XCM World Cup in Czech Republic, as well as the XCM World Cup in Finale Ligure, Italy. I got selected to represent Sweden in both European Championships in Laissac, France and World Champs in Glasgow.

I am also an university educated coach that focuses on cycling. Right now I'm working at Toppfysik as well as on Swedens largest high schools that has cycling as part of their education, so I work as a coach there as well for 16-18 year olds.

I mentioned that I got more strict with the heat training in the last year or so, but what changed?

The things I did before I still do, but now I run a more strict protocol to keep track of my core body temperature. I have also tested out different methods, timing, amount of heat stress, length of the heat training period and more. I believe I have found something that works really well for me.

Let's dive into it!

Question: How many heat training session per week?
The length of my heat training blocks have varied during the years, but now I've found that about 10 days is the perfect length for me. The tools I basically use is an indoor trainer with the CORE Heat Suit as well as a Sauna. This period looks a bit like:

DAY 1: Normal training outside + 30-40 min sauna

DAY 2: Normal training outside + a 1 hour Zone 2 heat training session on the indoor trainer with the suit

DAY 3: Normal training inside + 30-40 min sauna

DAY 4: Normal training outside + 30-40 min sauna

DAY 5: Normal training inside + a 1 hour Zone 2 heat training session on the indoor trainer with the suit

DAY 6: Rest day + sauna

DAY 7: Long ride outside + sauna

DAY 8: Normal training inside + a 1 hour Zone 2 heat training session on the indoor trainer with the suit

DAY 9: Normal training outside + a 1 hour Zone 2 heat training session on the indoor trainer with the suit

DAY 10: Normal training outside + 30-40 min sauna

This is an example during the winter/spring days when I don't have a competition on the weekend. 

Now you might ask yourself, are these heat training sessions done as part of a workout or separated from your normal training sessions?

I land in about four Zone 2 heat training sessions on the trainer and 6 sauna sessions in this block. Could vary a bit but normally like that. Most of the heat sessions on the trainer are separated from my "normal" training with a few hours between. The sauna sessions I almost always do right after my normal training, while my core body temperature are already elevated from the training. 

But how does a heat training session look? You mentioned Zone 2 a lot.

Yes, if I dive in to a specific heat training session it looks like this: I put my bike in the trainer and put on my heat suit and weigh myself (just to know how much fluid I loose during the session). Then I do a 10 minute warm-up before I do a 5 minute threshold effort, to stress my core temp up and to start sweating a lot. The last 45 minutes I keep my watts in the middle part of zone 2 and watch my heart rate slowly go up into zone 3. It gets pretty uncomfortable the last 20-25 minutes. I also keep my water intake to 500ml/hour during the session, but I make sure to refill that after! Since Core Body Temp released Heat Strain Index (HSI), I've used it in some sessions to keep the heat load in check. More on HSI a bit later.

See picture below. This looks like my typical heat training session on the smart trainer.

Grey: HR, Pink: Power Output, Green: Core Body Temp

As you can see the core temp starts rising about halfway through the threshold effort and slowly starts to plateau in the last 10 minutes. My heart rate is pretty stable at 120 bpm to the 25 minute mark around the point where my core temp has raised about 1°C from my "normal" state (not from the start of the session). This is a time in the session there it starts getting a bit heavy mentally in the heat suit which feels very warm. I have divided back and fourth with myself if I should lower the watts and dress a bit warmer instead, to keep the mechanical load even lower. But I concluded this has been working well for me and why change a winning concept. Below you can see the exact same training session, but shows sin temperature and inside temperature as well.

Grey (background): Core Body Temp, Blue: Skin temperature, Grey (line): inside temperature

My smart trainer are located in a big industrial premises which is quite hot in the summer but pretty nice in the winter days. In the summer normally is between 21-23°C inside and about 20-25 % humidity. I Can't really change the indoor temperature that much, and I keep the sessions low intensity with an higher intensity effort in the beginning of the training session to boost up the core temp. That basically means that I rely on clothing to raise my core temperature to the right zone.

Most of the heat sessions I do during my block is sauna sessions. Those are a bit tricky since i can't measure my core temp with the sensor inside the sauna. I've tried to have my heart rate monitor and sensor right outside, and walked out and put it on in a break. But I find it taking a bit too long and it takes time to accurately measure the core temp, so right now I take sauna sessions based on feel. 

I normally sit about 30 minutes in 80-85°C. Sometimes 40 minutes if I experience the sessionRPE manageable. If possible I do the sauna sessions straight after a bike ride, when the core temperature is already elevated from training. Normally around 38°C when I enter the sauna which should raise up to 38,5-39°C in the half hour I sit there and that is in the right span according to my Heat Ramp Test. 

Heat training zones and Heat Strain Index
To maximize my heat training I'm using my individual Heat Training Zones as well as keeping an eye on the HSI. Too much and too hot is damaging more than making myself faster. Below you see the HSI for the workout. It is on the upper limit of what Core Body Temp themselves recommend (keeping it to 3-6 HSI). Normally I land between 4,8-6 when I'm using the CORE Heat Suit. In the second print screen you see my personalized heat training zones and how much time I spend in each. I don't want to be over 39,2°C because that stresses my body way too much. High 38 is good for me. 

In my experience, using the CORE Heat Suit, it isolates and keeps my skin temp much higher and closer to my core temp compared to using "normal" clothes (arm/legwarmers, jacket, beanie, buff) and therefore I get a steady raise in heart rate when I'm using the suit compared to otherwise. 

I did a post in the CORE forum about this about a month ago and hoped more would share their experience, but not yet.

2 kommentarer:

  1. Intressant! Hur länge håller en Core Heat Suit? Är du fortfarande inne på din första eller har du fått byta? Kör du storlek M?

  2. Hej!
    Ursäkta sent svar. Enligt CORE själva håller de ca 10 träningstillfällen, men jag har körde min första en bra bit över gränsen och den blev väldigt mycket sämre i att bibehålla värmen, speciellt i resårerna kring handleder/fotleder. Man köper dem i 2-pack. Jag har medium, men den är ordentligt stor.

    Är man ovan eller aldrig kört värmeträning förut rekommenderar jag dock först att köra med sina "vanliga" cykelkläder med ett extra lager för att vänja sig. Trots att jag gjort det i några år så var det absolut inte en behaglig upplevelse med dräkten första gångerna.