Tired Runner.

Help Your Athletes Heat Train Safely

BY Phil White

There's no need for your athletes to roast in a sauna for an extended period of time. Proper heat training hinges on regularity and quality.

In a recent article, I explored some of the evidence-backed benefits of heat training. These are equally applicable whether your athletes are going to be competing in hot conditions or not. But before you get them started, let’s look at some best practices for doing heat exposure safely, so that you’re coaching your clients responsibly. 

In many countries, regular heat exposure isn’t considered “training” per se — it’s just part of daily life. People often frequent onsens (hot springs) in Japan, communal hot baths are common across Turkey and Russia, and Scandinavians routinely use saunas. I first came across heat training while researching my book Unplugged with Andy Galpin and Brian Mackenzie. In doing so, I got pretty deep into what the evidence tells us about heat exposure and how to apply these insights in a safe manner. Let’s take a look so you can share a few basic protocols with your athletes. 

1. Start with short sessions.

You probably wouldn’t ask a novice runner to start logging triple-digit weekly mileage right away, and neither would it be wise for your clients to jump headlong into heat training. A gradual ramp-up is a much more prudent approach that will allow their bodies to adjust to the stress imposed by heat exposure without going too far too quickly. 

The participants in a Finnish study that we’ll explore in more depth momentarily spent an average of just 17 minutes per session in a sauna. Some of the participants noted positive impacts on their health after heat exposure as brief as five minutes, while few went over 20 minutes. Another study conducted by Japanese scientists found that 15-minute sessions in warm water reduced chronic fatigue symptoms. The takeaway? Your clients won’t derive much, if any, additional advantages from staying in a sauna, hot tub, or bath for longer than 20 minutes at a time. 

2. Go cooler than you think you can handle.

You’ve probably got plenty of hyper-competitive clients in your group. That’s great to foster competition between them and themselves, but heat training is a risky modality for type-A strivers who like to push themselves to the limit all the time. And to be blunt, it’s not the right setting for a pissing match about who can handle hotter for longer. Such one-upmanship is actually very dangerous and could lead to a medical incident or worse. 

With this in mind, you need to help your clients set some boundaries for heat exposure, particularly for those athletes who are new to it. You might let them know that, according to the scientific literature, you don’t have to turn up the thermostat all the way to start seeing physiological advantages in both performance and overall health. A study published by researchers from Loughborough University in the UK found that hot baths offer similar benefits to an hour of cycling. And unlike a sauna, which can be set as high as 150 to 175 degrees Fahrenheit, the participants in this particular study were only exposed to a temperature of 104 degrees — the same as a hot tub or good ol’ hot bath.   

3. Know when to stop.

My former colleagues at XPT once shared with me that as soon as your forehead starts to get sweaty, you can stop your heat session. They weren’t saying that you should never go beyond this, but rather, a few minutes of getting hot can start to stimulate immunity-promoting heat shock proteins and kickstart the other beneficial adaptations that heat exposure promotes. As your athletes build up their tolerance, they might want to stay in the heat for a bit longer. But if they begin to feel woozy, confused, or upset, they should use this as a signal to stop the session right away. 

The same goes if they start to get excessively thirsty. Remind your athletes that there is no Olympic event for how long someone can stay in a sauna and that unlike when they need to push through fatigue and finish an arduous training session, the time to stop heat training is when it becomes uncomfortable. Once they’ve been doing heat exposure regularly for a while, you could suggest that they do a little contrast therapy, breaking up heat exposure “intervals” with short periods in a plunge pool, cool river or cold shower. That way, they’ll be able to chill out after getting hot, and also tap into the benefits of cold exposure, which include resetting the autonomic nervous system, activating cold-shock proteins and building mental resilience. 

4. Consistency is key.

Like every other stimulus your athletes subject themselves to, they will eventually hit a point of diminishing returns with heat training. But perhaps surprisingly, the number of weekly sessions that remain beneficial is actually quite high, according to the latest research. While they can get the benefits of weight training and fast intervals from as few as two workouts per week, your clients might want to double that to reap maximum training (and even longevity!) rewards from heat exposure. 

Researchers from the University of Eastern Finland followed the health of 2,300 middle-aged men for an average of 20 years and found that over the course of the study, 49% who only used a sauna once a week died during the course of the study, compared to 38% of the thrice-weekly group, and just 31% of those who visited the sauna four to seven times per week. The rates of heart disease followed a similar pattern. This implies that the more often your athletes get hot, the better their cardiovascular and overall health will be. 

5. Hydrate and rehydrate.

Much like if they were running, cycling or lifting weights in hot and/or humid conditions, heat exposure is going to prompt dehydration through sweat loss. And the mineral they’ll lose most readily is sodium. To this end, your clients would do well to take a cue from Russian bathers, who always have a glass of water with a pinch of sea salt in it while they’re soaking. After an athlete gets out of hot springs, sauna or hot tub, they will also need to rehydrate. A long-time friend of TrainingPeaks, Dr. Stacy Sims, once told me that sprinkling a pinch of salt on water-rich fruit like watermelon is a great choice in such a situation. Or you could follow the lead of ultrarunning legend Kilian Jornet and make up a big batch of gazpacho to help you both refuel after regular training and rehydrate after heat exposure sessions. 

If you can get your clients to follow these guidelines, there’s no reason that they cannot perform heat training consistently and safely. As with any other kind of regimen, advise them to consult their physician if they have pre-existing conditions that might preclude them from intentional heat exposure. 

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About Phil White
Phil White is an Emmy-nominated writer and the co-author of The 17 Hour Fast with Dr. Frank Merritt, Waterman 2.0 with Kelly Starrettand Unplugged with Andy Galpin and Brian Mackenzie. Learn more at www.philwhitebooks.com and follow Phil on Instagram @philwhitebooks.

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