Active vs Passive Heat Training: Which Works Better?

Heat adaptation can improve performance, comfort, and recovery in hot conditions. But many athletes make the mistake of treating heat training as free fitness.

In this episode, CTS Coach Adam Pulford breaks down the differences between active and passive heat training, how each method works, and why heat should be viewed as a training stressor in its own right.

We discuss plasma volume expansion, sauna protocols, heated trainer rides, hydration, recovery considerations, and how to integrate heat adaptation without compromising the quality of your training.

HOST

Adam Pulford has been a CTS Coach for nearly two decades and holds a B.S. in Exercise Physiology. He's participated in and coached hundreds of athletes for endurance events all around the world.

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Resources:

• Beat the Heat – a hot bath after exercise boosts performance in the heat
• Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies - PubMed
• Active vs. passive heat training: which is best?

Transcript

Why Heat Training Matters

SPEAKER_00 0:00

You can't just sit in a sauna for a few days in a row and think that's good enough for actual heat training. To make an impact and to form long-lasting adaptations, you need to be more deliberate with your time in the heat. Heat training is a sexy thing right now. Most pro teams use it as a strategy throughout their season. And there's been a ton of great research to confirm the benefits on both amateur and professional athletes. And heck, even NPR has been reporting on the benefits of being adapted in the heat in an ever-changing environment here on planet Earth. Now, you don't need to be an NPR nerd to realize the full weight of how broadly this messaging is, both in our endurance world as well as the rest of society. The real benefits of heat adaptation are that you perform better in the heat, you feel more comfortable while being exposed to it, and you recover faster after stressful bouts of exercise in a hot, humid environment. And if you're going to compete and do extreme things on a bicycle in extreme environments during the summer, you should probably have a strategy that involves some kind of heat training. If for nothing else, other than to minimize the chance of ending up in the med tent at the next race due to heat cramps, heat exhaustion, heat stroke, or worse. So now that I scared you into it, let's talk about the best ways to train

Active Versus Passive Heat Training

SPEAKER_00 1:28

for the heat. Essentially, there are two ways to train yourself to be adapted to the heat. Number one is active, and number two is passive. Active heat training simply means you're exercising in a warm environment to further the stress to the body in similar ways that endurance training already does, such as increased core temperatures, sweating, fluid loss, things like that. Passive heat training means you're sitting or existing in a hot environment that stresses the body to the point of similar elevated heart rate, core temperatures, and sweating, to which core temps are high enough and you get enough time and exposed, then you rest and you replace the fluids lost, you will form an adaptation to the heat. On a very basic level, I want you to view heat as a stressor itself. Separate from training, start to think of how this works. If you get stressed enough by the heat, your plasma volume expands, meaning the watery portion of your blood increases because your body recognizes it needs more fluid to handle this heat thing. You have more fluid on board then to help circulate your blood, cool yourself down when you're hot, and more total fluid to use when you lose it through sweating. It doesn't exhaust you as much compared to when you had less of the adaptation. And that is how the heat training response works. So you can use a little heat plus exercise to get there, or higher heat with no exercise, but either way, you're doing the same thing. You're increasing the core temperature, increasing heart rate, increasing sweat rate, and you're increasing total stress. Then you rest and you get better by tolerating both heat and stress together. Let's

Heat As A Stressor Explained

SPEAKER_00 3:22

talk about passive heat training first. So if you can just sit there in a hot sauna or a hot tub and get all the benefits, why not just do that? Right. It sounds awesome, doesn't it? But it's slightly more complicated than that, especially if you want the best effect for endurance performance. In particular, the complications are around timing, total time exposed to the heat, and some kind of measuring system to make sure that the stress is high enough to elicit a response, all while not overdoing it to ruin your recovery or stressing yourself out too much in the process. Additionally, having the resources like a sauna or a hot tub or a big bathtub to soak in for 20 to 40 minute post-exercise can be a drawback for some people. So just realize it may not be as simple as it sounds once you put it into action in your normal everyday life. I'll get into more of that here in a minute once I go through the different protocols. Now let's do a quick word on active heat training. Poor persons heat training is and always has been exercising on a hot day. As simple as it gets, this is active heat training. These days, most people with smart trainers will ride inside with no fan and either some extra clothing or a specific heat suit that can really increase the heat stress. And this is active heat training too. While some of these options are much more approachable to most people, there are limitations, pros, and cons here as well. In particular, if you don't live in a hot environment or if you don't have an indoor training setup, then this is not an option. Additionally, this is where I see a lot of common mistakes. Those who do active heat training but do not decrease their intensity while riding will certainly overcook themselves. In the end, for my athletes, I use both strategies together to optimize their normal training with their heat training adaptations so that they're better prepared to perform their best when the heat hits. As a blanket statement, I would say being heat adapted has more pros than cons, meaning there is a lot of upside to it. The cons are generally an increase of time, but with some simple shifts in habit and deliberate sessions, you can increase your performance in the heat, minimize the risk of heat-related illness, and become more efficient and cool in yourself while bouncing back sooner after a hard day in the heat on the bike if you're totally heat adapting. So, how best do we do

The 7 To 15 Day Protocol

SPEAKER_00 6:08

this? And what methods have I seen to work best with my athletes? Let's look at the protocols first. High-level protocol, just think about heat exposures here for a minute. And this could be uh passive, active, or both. For most athletes, I'm aiming for at least seven days of consistent heat exposure and up to as much as 15 days consecutively. Yes, you need to do this back to back to back days all in a row for at least a week, but ideally two weeks. That means if you're going to do this, you need to commit. Otherwise, you're you're just half-assing it and you're not getting the full benefits of the adaptations that you could. More specifically, you could be inducing more stress on yourself and not getting all of the gains. So you're better off either not doing it at all or just waiting until there is a time period where you're not traveling or you don't have a million things going on so that you can do the training and form the adaptation. Once you do, you can maintain it by doing less. So once you've committed to about two weeks of heat training, you need to make sure that your sessions are hot enough and have enough time and zone, so to speak, in the heat. For active heat training or riding in the heat, what I recommend based on practical application as well as the research that is currently out there to maximize everything for heat training is you ride for at least 60 to 90 minutes total. Target a power of zone one or low zone two, and eventually see heart rate drifting up into high zone two or zone three. Now, I'll explain this much more in detail when I walk through the practical applications of this, but this is just the high-level protocol. You should feel hot within the first 10 to 15 minutes of riding, and the effort should increase over the course of the whole ride. Ride like this, inside or out, at least seven days in a row, or ideally, like I said, about two weeks or 15 days for full adaptation to occur. For passive, so this is using sauna, hot bath, or a hot tub, total time should be around 20 to 40 minutes post exercise. This is the key thing. You want to jump in the sauna or in the hot bath as soon as you can after training to capitalize on your core temperature already being elevated, as well as your body being stressed and depleted from fluid, glycogen, and other things from training. Recall that heat is a stressor, so adding high heat stress after hard training stress delivers a double whammy that is far more effective than just sitting in a sauna for 15 to 20 minutes on some random point during the day. The sauna should be hot, like 70 to 90 degrees Celsius, or around 160 to 200 degrees Fahrenheit. The hot bath should also be hot, but more like 40 degrees Celsius or around 102 to 104 degrees Fahrenheit. For either hot passive strategies, start with a minimum dose of 10 to 15 minutes post-exercise, or however much you can tolerate. Then build up from there. 20 to 30 minutes at most for the sauna and up to 40 minutes for the hot bath. Again, post-exercise. More is actually not better, as these seem to be the point of diminishing returns both in practice and in research. Now, let's

Heated Endurance Rides In Practice

SPEAKER_00 9:40

put these protocols in real life action. For active heat training protocols, this is the heated endurance rides. Remember, I said 60 to 90 minutes total. How you actually do this is that you start with a sweatshirt or something more than just your normal cycling jersey, and of course, your regular bib shorts. But you don't need to wear more than that. No fan, nothing to cool or circulate the air, and this is key. Just ride at the lower end of zone two for your power and watch the heart rate climb. You should start to see heart rate increase to upper zone two and lower zone three, which is tempo, and RPE should increase with it. Recall that normally lower zone two should feel like a two or four out of ten. Tempo should feel like a six to seven out of ten. So if the heat is up, keep the power low and let the stress build and use the heart rate and the RPE to confirm this, especially in the first five to six days of heat training. For advanced riders and for my elite athletes, I have them actually spin easy for only like five minutes to start. Then I do about 15 minutes of uh tempo power to drive the core temperature up faster. Then I settle into low zone two, and then we carry on as normal. We get more time in zone this way because the heat starts higher sooner, and we get better results. But again, that's an advanced method. If this is your first time doing heat training or you're more of a beginner, just stick to the zone one or low zone two plus no fan strategy. You may just ride in a regular jersey for the first five days, and you should be plenty hot and sweaty if you're riding

Hydration And Safety In The Heat

SPEAKER_00 11:26

inside. My pro tip on this is to stay hydrated during these sessions. You want to drink normal or more than normal during a heated training session. So that could be 500 to 700 milliliters or roughly 20 to 30 fluid ounces per hour of sport drink with electrolytes and pure water as the minimum. But it could be up to one liter or around 40 fluid ounces per hour if needed. Drink plenty of water afterwards as well. And if you lost weight during the ride, you want to drink back about 1.5 times the amount that you lost. So if you lost one kilogram, which is roughly one liter of fluid, you want to drink back 1.5 liters in the first 90 minutes or so post-exercise. If outside, my advice is similar. Keep it to low zone two power, watch the heart rate drift up higher into zone three, and RPE should go up with it as well. You should be sweaty and feeling pretty uncomfortable. Now, the first five to seven days are the roughest for most people. So keep it aerobic, be consistent, and remind yourself to play the long game here. Whether you're layering up and going outside or it's just hot and you wear regular clothes, riding hot will do it. Especially if you see the aerobic decoupling of the power to heart rate, like I just described. If the outside temp is like 32 degrees Celsius or over 90 degrees Fahrenheit, and it's really humid, just be careful. Start low, go slow when you're doing this, and that'll be the safe way to get adapted to the heat.

Trade Offs And Common Mistakes

SPEAKER_00 13:06

Let's talk about some drawbacks. Keep in mind there's always trade-offs when trying to make the best decisions about the best training strategies. For active heat training, you need to decrease intensity while first riding in a hot environment. This is because your body is not ready to handle both high intensity and high heat at the same time. It needs exposure to the heat first to increase the plasma volume and a few other things to make it simple. Then you can hit both high intensity and high heat together with confidence, but you need to form the adaptation first. Now, if you only have 90 minutes total to train each day, that may be it for you. But you're making the decision to stay away from intervals or high intensity in the short term to get the heat gains in the long term, and all we need is at least seven days, remember? In up to two weeks, ideally. Now there's some coaching art to make sure that there's balance to it all. And I'll cover that more when I talk about using both methods at the same time.

Sauna And Hot Bath Logistics

SPEAKER_00 14:11

But let's talk about passive heat training protocols first. I ripped through the high-level protocols a few minutes ago, but the practical side gets more complicated for the time-crunched athletes because of the lack of time. Pros and time-rich people with resources like a hot tub, sauna, or a big bathtub have everything they need to get this thing done. But if you're working at the office and you have 60 to 90 minutes to train each day, then shower, then get back to it, you in reality can't do passive heat training like this. That's just how it is. So waiting for the outside environment to get hot enough, then aim to do an active protocol is the way. Everyone's jazzed to get their heat training going, but this is what a lot of people don't really think about. If you're doing a hot bath protocol, for example, post-training, you need to get home, rack the bike, head to the bathroom, kit it up to save time, and start drawing the hot bath. As the bath water fills, toss the thermometer in if you have one, or have it handy so you can keep an eye on the temperature itself. Take the kit off, replace the heart rate chest strap with an armband uh strap if you really want to nerd out here, because that's actually really important to see if the heart rate is going up while the heat is stressing you. What you should look for is for that heart rate to get up into like a low zone two, maybe even middle of the zone two uh heart rate that you would normally see on the bike. And that's to make sure that the heat is actually stressful enough in the hot bath. Now, you don't eat or drink anything when you're doing this, by the way. You're trying to stress your body with this double whammy. When you finally do step into the bath, just know it's going to be super hot. You're not going to want to spend a ton of time in there, but you need to get your time in the zone. So start low, go slow, but start to rack it up to track your progress. Couple things here. If you're sweating more sooner, it's working. If heart rate goes up in the bath, it's working. If your perceived effort goes down, eventually, after five to seven days of doing this hot bath protocol, it's working. Now, back to the practicality of doing this hot bath protocol. After the tub, you need to shower off, then start with a rehydration protocol, which I mentioned in the active heat training session where you're drinking back what you lost. All of that being said, it is kind of complicated. And if you don't have the bath or an extra 40 minutes or uh something like that, again, this may not be for you. The sauna is a little bit easier because there's less logistics anyway, but most people just don't have a sauna laying around post-ride wherever they're riding on a given day. If you do, lean into it. That's awesome. The drawbacks here are obviously time, timing, and resources. If you can't do any of this because you can't time it, or you don't have an extra 30 to 40 minutes post-exercise, or you don't have a sauna or the big bathtub to submerge yourself, it's not worth it. But the benefit of passive heat training is you don't have to change training or decrease intensity while you do it. You can do your training program, cook yourself after, and move on. Okay, let's talk about both protocols together.

Combining Methods And Maintenance

SPEAKER_00 17:41

I find that the best strategy is to combine both passive and active heat training protocols together to get the most benefit from training and the heat. Essentially, as long as you can get one exposure per day as I described, you'll be on track to make the progress. So, for example, you could keep Tuesdays and Thursdays as hard intensity days, then jump on the sauna after those training sessions, while doing the other days as heated trainer days. Or you could do double days where you do your intensity in the morning with no heat, then you do your heated ride in the evening and you do that two times per week. Then on the other days, you do normal riding and jump in a hot bath afterwards. If my athletes are racing in the heat, I want them to train in the heat. So while the passive strategy helps in keeping intensity up, I still want to expose them to what it really feels like to ride and push in the heat before race day. I still limit intensity the first week or so in my active heat training protocol. But with my one-on-one athletes, I may nudge up the intensity to zone three or short bouts of threshold, zone four, to get the combination of heat stress and training stress, especially if they've done heat training before or if they're an advanced athlete. Once we've done about two weeks of heat training, the maintenance is not as heavy. Basically, every five days spent away from heat exposure, you need one active heat training session to maintain the gains that you got. So, how I manage that is I make sure that the athletes are doing a heated ride inside or out every four to five days to top off the body. If I can't do a heated ride, I'll do a passive post-ride exposure of 20 to 30 minutes every three to four days. And that's just working fine, based in my experience. For anyone doing this, I do encourage them to keep intensity low for that first week so not to overdo it with all the stress from heat, training, and life, and gradually weave it back in come week two as your body forms the adaptation. Just keep the durations shorter than normal and pepper in a few uh sprints on your endurance days, and that's gonna maintain things fairly well. Really push and commit to that 15 days total for full adaptation, because by the books, that's the best. Some

How Fast People Adapt To Heat

SPEAKER_00 20:10

research says that men may adapt sooner, like seven to ten days, where women will take slightly longer, like 10 to 15 days. Now, I tell my female athletes this is because they're just so tough and they need more total stress to move the needle, whereas the men are kind of wusses when it comes to heat. And while some of that is actually true, there's a lot of other complicated things going on, like hormones and the women's monthly cycle that plays into it. I've linked to some of the resources on this from Dr. Stacy Sims uh here below, as well as some great research from Perard on all things heat training for the really diehard nerds out there. A really good infographic that summarizes all things hot bath related from Oscar Zhukenroop is down there as well. If

Coaching Options And Next Steps

SPEAKER_00 20:59

you want to bootstrap all this yourself, but if you don't, and if you're like, oh, I was doing it all wrong, or wow, that's way more involved than I thought, you're not alone. And that's where we can help. Each CTS coach has a degree in exercise physiology, psychology, biology, or some other applicable ology with specific performance-related training like heat training, to develop you to be your best. We offer one-on-one coaching to focus on individualized, personalized programs, but we also offer the train right membership, which is a more cost-effective way to get access to CTS workouts, training tips, and other perks. Additionally, we do offer coaching consults where if you just want to talk with a smart coach on how to apply something like active heat training into your already existing program, you can bend the ear of one of our coaches for an hourly fee. In the end, between this video and all of our services, we try to offer you everything that you need to be your best athletic self. For me personally, when I hear someone tell me that they really like the videos or the newsletters or one of our CTS coaches, like Noah Noinsky, helped them to get a PR this weekend. I'm stoked out of my mind because I know how challenging it can be to take complicated information and apply it to a busy, complicated life and try to get a result. It's tricky, but it can be done. And when you train right, you'll get more results

Final Takeaways And Sign Off

SPEAKER_00 22:29

sooner. Thanks for watching and listening today. We'll see you back here soon for the next one.