[edit] I’ve recently made some modifications to the protocol below. 1) starting the sauna in an already dehydrated state (for example after 1 hour run with no water) and 2) not rapidly rehydrating after the session. You want to rehydrate slowly over the course of several hours. These two aspects will increase the adaptations to the heat stress.

If you have a hot race coming up, or even if you don’t, heat acclimation will be a worthwhile addition to your training program. The obvious benefits of heat acclimation will, as the name implies, prepare you to suffer less while racing in the heat. There is a mental conditioning aspect but several key physiological benefits:

• Increased blood plasma volume
• Increased blood flow
• Increased red blood cell count
• Lowering of core body temperature while exercising
• Heat shock proteins can aid recovery
• Increase in Human Growth Hormone (HGH)

Of course these adaptations are going to help you in a hot race, but most of them are also going to help you in cooler conditions. So these days I actually include heat prep for all races whether they are hot or cool. The video below outlines some key benefits of hyperthermic conditioning. Take a look if you want to dive into that… but let me outline the heat prep protocols that I use myself…

Let me start off my saying don’t do anything stupid. Consult with your doctor before spending time in a sauna, and use common sense. If you have any underlying medical conditions, be sure to check with your doctor first.

Basically, my first goal is to build up to 30 minutes of sauna time. Initially, I might not be able to sit in a sauna for 30 minutes straight, so I break it into “intervals”. I’ll sit in the sauna until I feel very uncomfortable, then get out for a short break, and then get back in again until I feel that discomfort again. I repeat that process until I’ve accumulated 30 minutes in one session. With each visit to the sauna, I can make each interval last a bit longer. I just repeat that until I can last 30 minutes in a single sitting. So for example, on session one I might do 3 x 10 minutes. Session two might be 15 minutes, 10 minutes and 5 minutes. Session three 25 minutes and 5 minutes. And then session four 30 minutes. Once I can do 30 minutes, I try to do that several times a week in the 3 week period leading up to a race.

The thing to bear in mind is that heat prep is a stress on the body. It can affect your workout quality, and should also be considered in your overall training and stress load. For that reason I always make sure that I’m smart about the timing of these sessions:

• I never do a sauna session before a workout, always after. If possible I do it directly after a workout since my core body temperature will already be elevated.
• If I have multiple workouts per day, I try to do the sauna after the final workout. If I don’t do that, my workouts after the sauna session are compromised, even if they are later in the day.
• During recovery blocks, I supplement the sauna sessions with heated workouts. For example an easy spin on the indoor trainer, in a heated room without a fan, heavily overdressed in warm clothes. Or a run at midday dressed in my ski gear. I keep the workload easy, which helps to limit muscular strain but I still get the physiological benefits of the heated sessions.
• 3 weeks seems to be sufficient for a heat prep block. I don’t do any heat prep during race week since no further adaptations are required, and I don’t want the additional stress of heat prep during that time.
• Recently, I’ve started including heat prep year round. I’ve not yet experimented enough to know if this is beneficial or not, but so far in the first 4 weeks of 2017 I’ve no adverse experience with it.