The Science Behind Heat Exposure: Health, Performance, and Recovery

All right. Heat exposure for performance and recovery and health. Is it all the rage that it all makes out to be? At the moment, the world is getting fascinated with these exposure exercises, both cold and heat. And this session is today talking about the benefits of the heat and whether they actually are backed by science. If you do want to learn more about the cold, I'll pop a video just up here now and you can click that and you can have a look at the benefits of cold, particularly if you want to enjoy them during exercise. My name is Martin McPhillemy, I've been an exercise and respiratory physiologist for over 15 years and this is just what I do. I love delving into the science. I've got a certification in the breath science certification. If you want to look at that, I'll pop the website that you can take a look at down there. Anyway, today let's talk about the heat. The heat can be used for multiple different reasons and we're going to take a look into those. Obviously people have used sauna in Finland for thousands and thousands of years and they have very typical and brutal protocols. However, today's session, I'm just going to quickly go over the types of heat that we can use. Now. We have hot baths, we can use a hot bath for example, if we want someone to become adapted to the heat. Now why might we do that? We can use a hot bath or we can simply get them outside exercising. Exercise is the key thing here for athletes. There are a few reasons to why I think that people might want to become adapted to the heat. Number one, we know that when you are in the heat and you exercise, you are exaggerating the amount of stress that your body is feeling. We'll get into the mechanism of that in a moment and essentially you're going to breathe faster, you're going to warm up faster and you're going to body's going to be under a stress and therefore you're more likely to get central fatigue from our brain and our central nervous system. So becoming adapted to to heat for an acclimatization reason for beforehand can actually help the individual not only perceptually but also physically able to sustain stress in the heat long term and therefore improve exercise performance. However, that might not be always the case for why people want to improve their performance per se. But let's say we've got an athlete who is needing to make a weight cut and they dread the weight cut because every time they get in their sauna or they get in their sweat bag the heat is just horrible for them and it just makes them feel like crap. And therefore, as a result, they struggle with the weight cut. It's hard enough anyway, but also they are then feeling tired and fatigued and maybe they've only got 48 hours until they have to perform. So using a hot bath regularly, or even better, obviously we've got saunas. Now, in terms of a sauna, we have infrared and we have traditional saunas. The issue with infrared is that they will warm the body up from the inside. And for that to have an impact enough to be able to raise your core body temperature to cause distress is likely to make you feel too hot before you can actually get there. And you have to spend longer times of periods in an infrared sauna, which will be challenging. Therefore, it's not as good as a traditional sauna. So a traditional sauna obviously won't use infrared. It will use rocks and heat and steam. That is more so like the environment itself is getting warmer and therefore the core body temperature can actually get to a position of getting up to near 38, 39 degrees Celsius, where we are starting to really have the impact on that. So if we can utilize things like saunas or hot baths, then we can help athletes to navigate their acclimatization to heat away from training, away from weight cut, so that when the weight cut comes, actually they are better acclimatized for it. But that's not the only benefit. That's just some areas that you might want to look into. The other benefit is looking at cardiovascular disease. So there was a study based in Finland. The Finnish are only going to be the individuals who look longitudinal studies at saunas. And essentially at 80 degrees Celsius, if someone was to go into a sauna for 15 to 20 minutes per day, two to three times a week, they have a significant fall, roughly around about 25 to 30% reduction in death by cardiovascular disease. If that is then increased to maybe four to seven times a week, then that reduces more to 40 to 50%, which is a massive reduction in cardiovascular disease. So I just don't know why this isn't promoted by more cardiologists or even general practitioners. Now, obviously, there might be a few contraindications for people going to the heat, particularly if they're already dehydrated, if they're sick, if they are wanting to try and have babies. If you're in a period in your life where you're trying to conceive both males and females, it's advisable to Stay away from the heat, particularly males, because you're going to get a reduction in sperm motility. And that is not going to be beneficial for then obviously trying to have children. So there are some of the downfalls. People who have thyroid issues might just be, want to be aware of potentially changes in thyroid hormones that can lead to problems related to the heat. However, in terms of the benefits we talked about, cardiovascular problems we actually really want to consider here. What about athletes who are injured might be able to slow or prevent down deconditioning? What about people who have disabilities who struggle to exercise? It is, can we use the heat to improve their heart health? When we actually look at the mechanisms of how it works, what we typically get is the part of our brain that is involved in recognizing physical exertion is called the central command center. And that central command center has a direct impact on our sympathetic nervous activity. So when we are in the heat, our body perceives it as a form of exertion and increases our sympathetic nervous activity. And we have an increase in respiratory rate, blood pressure and also our heart rate. So it is essentially like a exercise mimetic, particularly on the heart. Now the heart is going to start to beat faster. Sometimes it might go to 60 to 70% of maximum or increase by that certain amount. And we can see my heart rate typically might be around about 50 to 60. Resting in a sauna after around about 18 to 20 minutes, it gets to about about 130, 135. So getting close or at that zone two cardio position, this is going to have a huge benefit for muscle. The muscles of the heart are staying healthy. So there are clear benefits for heat exposure in that realm. The other thing that occurs is heat shock proteins. So heat shock proteins are released to try and help protect proteins from breaking down in the heat. And it's been shown that heat shock proteins are beneficial for people who are vulnerable for things like Alzheimer's, Huntington's disease, Parkinson's disease, and through gradual exposure and acclimatization to heat. Meaning that we don't just jump in and go as hot as we can, as long as we can straight away is we can get the continual benefit of these shock protein and therefore we can utilize the heat over a long period of time. The issue is that obviously not everyone has accessibility to saunas. They are a growing popularity and majority of places around here in Australia at the moment. So I don't know about in your country how accessible saunas are. If you do pop a position or a place that you do know or do like in the comments below. The final thing that I really want to consider here is around recovery from exercise. And people talk about hormone changes with heat exposure. And there are studies that suggest extreme heat exposure might have an impact on increasing growth hormone. However, I think the main benefit really from heat exposure is to do with what we can do in the evenings. Obviously everyone and recovery is about majority of it is about sleep, which we're actually going to start discussing in the in future videos. One of the major components of sleep is that we get typically into what's called stage free sleep. And stage free sleep is where we get the release of hormones that will then communicate to our cellular clocks to start to convert energy into a biological investment, rather than providing energy to waking vigilance into cognition, actually to repair itself, repair the muscles and clean out the brain debris, et cetera, et cetera, which is going to be beneficial obviously for exercise, but also for just general cognitive performance. So if we are to have that happen, for that, for the initiation to go from sleep from wakefulness to stage two into stage three sleep, we have to to have a reduction in core body temperature by roughly 1 degree Celsius. Now people can use the heat a couple hours beforehand, expose themselves to that. Then following the hypothalamus is going to recognize that the environment's warm. It's going to try to start to assist the process of shifting our blood flow to the skin. So sweating will occur. We'll get the production of sweat from the sweat cells, but also the movement of the blood vessels to the skin allows for the heat to dissipate. The cool water goes back into the core, sorry, the cool blood goes back into the core and that will then start to drop our core body temperature as we get out. If we do that and time that appropriately with trying to get to sleep, there are evidence to suggest that we can probably see improvements in sleep quality there and thus potentially improvements in things like stage free sleep and recovery from exercise or just recovery in general. So there are some benefits to using the heat. I haven't gone through all of them, but particularly the major benefits are for acclimatization, cardiovascular improvements, and potentially improving recovery through the means of improving sleep quality. So if you enjoyed this video, please, like subscribe. I'm going to pop a little video up here that is all about the cold. So if you wanted to jump onto that one next, then you can do that in Joyce.