Editor’s note: Altitude training is a traditional way of creating hemoglobin gains. While heat training has been shown to deliver similar hemoglobin gains as altitude, some athletes are hesitant to completely give up altitude training, and believe it gives additional benefits.
Triathlon coach Roy Hinnen has shared his protocol for both heat adaptation and gaining hemoglobin (for VO2max gains). It involves heat training followed by altitude training followed by another block of heat training. Roy also did before/after lab testing and documented his hemoglobin gains.
Roy has been coaching since 2002. As a life-long athlete (he trained with triathlon legends Dave Scott and Mark Allen), he is constantly testing new training methodologies to improve performance.
Very warm room temperature
CORE’s Heat Strain Index shows you can get physiological adaptations with various combinations of core temperatures and skin temperatures. Core temp is most influenced by your exercise intensity (heat you generate inside you), and skin temperature is most influenced by the air temperature and the clothes you wear.
For my protocol, I use a very hot room temperature. My experience has shown me that when the room temperature is around 40°C/104°F, my mental adaptation to heat is most effective. This is because the heat produced by the body is limited by my performance, because it is just too hot in the room. This results in my Heat Strain Index being quite elevated, even though core temperature is not extremely high.
Our bodies are much more familiar with the heat produced internally from intense exercise. As a result, mental adaptation effect is smaller than if I were exposed to higher room temperatures of 40°C – which is an entirely new stimulus to the body.
Your job is to find the perfect room temperature where you can still train lightly (above zone 2, around 20% below the threshold). For me that's 40°C, for you it could be between 32° and 44°C. Again, the room must be so hot that a maximum heart rate is not possible because it's too hot. [Editor's note: raising air temperature to 40°C/104°F is difficult in home settings – you can also do a combination of very warm air (32°C/90°F) and very warm clothing.]
The aim is to increase the sweat rate; your body should immediately notice that it is hot and want to cool itself down as much as possible through sweat. Please remember not to train too hard. Listen to your body. A heat strain index of 3–6.9 (shown on the CORE app) is 100% sufficient.
Heat sessions
Prepare 1L of water with 3.5 grams of salt (I prefer Himalayan salt); drink this around 60 minutes before training in the heat. Remember that our blood contains around 7 to 9 grams of salt per liter. During training, drink as much as you want and need.
Preheat the room. I have tried heat training in a variety of air temperatures. 40° Celsius is extremely hot but still allows me to train. I suffer a little at this temperature and this is important as I cannot push watts at this temperature. My pulse is regulated to max. around 130; that's zone 2 for me.
Train 5 times a week in the heat for 3 weeks. So, 15 heat training sessions. Intensity should be between zone 1 and zone 2 for as long as you can, then reduce the watts, so that your Core body temp is not going too high. After training, go into a prepared bathtub with a water temperature of 40–45°C and sit in it for 10 minutes. This training feels hard. Monitor your heart rate while in the tub, and cool down out if it gets too high. Note that the CORE sensor does not work in the bathtub.
Around half an hour after training, drink another liter of water with 3.5 grams of salt. The aim is never to have yellow urine when you train in the heat. I’ve tried heat training without drinking and concluded that it is better to drink a lot to help the body teach itself to sweat a lot.
Altitude, then more heat
After these 3 weeks of heat there is a 3-week altitude training block where you are not heat training. After the altitude training, there are another 3 weeks with 5 heat training sessions per week, then the competition. Even if you cannot do altitude training, you can convert the plasma into hemoglobin mass. The gold standard, however, remains the right combination of heat/altitude/heat phases before your competition.
Monitoring heart rate
With the right heat adaptation training, your resting heart rate drops by 2–4 beats. For example, my heart rate went from 34 to 32/31 and at the same time my maximum heart rate rose for 2–3 beat to 159, almost 5x of resting. In contrast, the resting heart rate also drops in training camps with lots of volume, but the max heart rate also!
When your resting heart rate does not drop anymore (and maybe even rises a bit again) and the maximum heart rate decreases again, it shows that adaptations are being lost. This can happen within a week or two of no heat training.
Blood testing
I underwent blood testing at a specialized lab before and after my heat and altitude training. In the initial test, I had an absolute Hb mass of 1055 grams with a blood volume of 7.995 liters, or 13.9 grams per kilogram of body weight. After the protocol (3 weeks heat, 3 weeks altitude, 3 weeks heat), I had 1127 grams Hb mass and 8.723 liters of blood, an increase of 6.8%, which is an extraordinarily large increase and was of course clearly reflected in my performance curve.