High temperatures across Arkansas and eastern Oklahoma next week should peak in the very spring-like 70s. As summer approaches and the days get hotter, many people prefer to stay indoors to escape the heat. But what if you enjoy exercising or gardening outdoors, or your job requires you to spend more time in the heat — construction workers or firefighters?
On the latest Short Talks from the Hill podcast, Rosie Perez, a PhD student in the Heat and Hydration Optimization Lab at the University of Arkansas, discusses her research with host Todd Price. She discusses how heat can have an effect on tactical athletes like firefighters and police, and she shares what she knows about beating the heat.
Todd Price: First off, what does the H2O Lab look like, and what kind of work are you guys doing down there?
Rosie Perez: Well, we do a wide variety of work. Since there are three doc students in there, we each have a little area of research we are interested in. My lab mate Sean — he's very interested in how endurance performance is impacted by heat. So we do a lot of sweat testing. He's going to gear up to do some work with, hopefully, the women's track team and see how that plays a role, and if there are any ways we can improve their nutrition to impact how they perform. Then my other lab mate Jack — he does occupational health. So we take guidelines like the NIOSH guidelines that have heat guidelines that tell us, OK, in this climate, how much work can they do? And then what rests do they have to do to follow up? And then how much do they have to drink? So he looks at how that plays a role, because if you can't work, you're not going to be productive. And then I am the last one, and I get to merge my background of working with tactical athletes — so firefighters and law enforcement — and kind of see how environmental physiology plays a role in their jobs. Since I have a strong background in strength conditioning, I get to apply that physiology standpoint. I look at heat and then apply it into how I program for them so that they're more prepped for what they're going to do.
Price: You've talked about it a little bit, but let's dig into it. What is the subject of your PhD here?
Perez: So my PhD, I have two areas. One, I look at how heat stroke is being handled out in the real world. I recently published a paper saying that exertional heat stroke and classical heat stroke, even though they show up in different populations, their pathophysiology is similar, and so we should treat them the same. That goes into a little bit of why are they not being taught the same? Part of it is looking at protocols. The states might have a certain protocol that they say they use, and then when you start looking at actual agencies, not all of them follow that protocol.
Price: Can we back up just a tiny bit? Can you just define exertional heat stroke and traditional heat stroke? Because I think most people probably just think there's only one kind.
Perez: So exertional heat stroke means that we have a physical activity — so typically we see it in athletes. They produce a body heat above 40 degrees Celsius, so that's 104 degrees Fahrenheit. They typically will end up passing out, they lose some consciousness after a while, they become very combative because they don't know what's happening around them. And so the point is to cool them. And then with classical heat stroke, it's passive. So when there's a heat wave like down in Texas and it's above 100 degrees all week long, they don't have access to air conditioning, then they can get exposed to that 40 degrees Celsius — that high heat — and that causes them to get a classical heat stroke.
Price: And you said these have been treated the same way, typically, or different ways?
Perez: Different ways. So with classical, a lot of people, since it happens in either pediatrics or older adults, they're like, oh, if we immerse them in cold water, then they're going to go into shock because of it. And as we're starting to see, there is data showing that actually immersing them in cold water gives them their best shot — it lowers the mortality rate, and it gets them cooler quicker. So that's what we really want — to have them cooled so that they don't cause any more damage.
Price: Getting back to your thesis: that's one part of it.
Perez: And then my other part is looking at how heat stress plays a role in tactical athletes. Right now I do predominantly work with firefighters because that's where I have the most access. We currently are looking at how cardiovascular disease is a common development in firefighters, and we want to see how we can mark when that's occurring. We're doing a longitudinal study where we have from the youngest being 18, all the way up to 47, and seeing how their cardiovascular measurements are changing throughout time.
Price: It sounds like Dr. McDermott is giving you a little latitude here on your PhD, because that sounds like it's a little outside of heat and dehydration.
Perez: He is. When I came into the program, he was very much like, you help with the lab, which I do, and then we can help you develop your research niche. So that's kind of where the cardiovascular measures come in. Partially why I also want to know those is hopefully for my dissertation, I'll get to work on how live fire training impacts them. So we'll actually see them do fire tasks and look at what's their physiological heart measures, what is happening there, what is their hydration there, and then even look at their kidneys and see, are they developing any buildup of metabolites in their kidneys that they need to flush out?
Price: People might be able to guess the answer, but when you're talking about EMTs, firefighters and people in these stressful situations having higher incidences of cardiac arrest, can you talk about why that is?
Perez: Well, there are a lot of factors that go into it. One of them is going to be sleep, because they don't know when their calls are going to come in — that does impair their sleep. Another one is diet. Sometimes they do have time to make healthy meals and other times they don't. Another thing that's really high in them is their overuse of caffeine. We typically see a high number of tactical athletes using more than 700 milligrams of caffeine, which puts a lot of stress on your body. And then the last one is their physical health. Are they actually fit for the job? Some of them do a great job — they work out, they continue doing what they need to do so that they can do every task of their job. While others might not, because they're really busy — when they get home off a shift, they have family, they have children. So it's hard to develop an environment that's always friendly to exercising. And then when they are at their stations, are those built up for them to actually get a good workout in? If they're used to being sore a lot after they work out, they might not want to work out because they don't want to be sore when they have to go do their job. We need to find a way to balance all of those markers. And then there's also genetics — if they're already predisposed to cardiac conditions, then they're at a higher risk.
Price: Let's just ask some super broad softball questions. First of all, what do people get wrong about hydration?
Perez: A lot of people think they have to drink so much water to stay hydrated. It varies depending on the person and how much activity you have. And then with athletes, we tell them, drink water, drink water, drink water, which can be a slight problem because they need those sodium and electrolytes we lose in sweat. So we want them to actually drink more carbohydrates — we want the carbohydrates with the sodium so that they can actually feel better. A lot of endurance athletes, when they go do hours of work, they're like, I'm just going to drink water. And we're like, no, no, no — drink some carbohydrates so that you can actually feel better during the workout.
Price: When you're talking about drinking carbohydrates, I assume you're not talking about Gatorade?
Perez: Gatorade, Powerade — they all have carbohydrates in them. They've all worked on how much carbohydrates we can take in. So those are actually what we want. We want them to drink those kinds of drinks.
Price: With summer coming, what are your recommendations for people who may have to work outside or want to stay active in the heat?
Perez: Build up your tolerance before going out. We have this thing called heat acclimatization. What this means is each exposure you get to the heat will actually help you feel better. It allows you to increase your plasma volume, which you need because that allows you to sweat more. We want people to, if they can, avoid being out there from about 10 to 2, because that's when it's the hottest, and try to move towards early in the morning or later in the evening so it's a little bit cooler.
Another false thing that we talk about a lot is people say stay away from dark colors. There aren't actually any studies saying that wearing dark colors in the heat are going to cause you to be hotter. We've seen studies that look at the shirt itself getting hotter, but when wearing it on a human, there are no studies saying that that human is hotter. So you probably don't have to worry about that. If you want to wear a black T-shirt outside, go ahead.
Price: This may be outside your expertise, but I'll ask — your recommendation sounds great for an athlete that maybe can acclimatize. But what about guys doing roadwork?
Perez: I would recommend wearing some thinner clothes — a lot of dry-fit — because we want their sweat to come off of them. The evaporation of sweat is what's actually cooling us, so not trapping the sweat in. They can work on exposing themselves before it gets really hot. Start when it's a little bit cooler — above that 86 degrees. Start staying outside for a little bit longer, because that will allow their body to adjust so that heat acclimatization would occur with them, too. If they can mimic some of the work they're going to do, they can also do that prior to getting into those long hours. And then during those long hours, making sure they're drinking enough electrolytes — so Gatorade is going to be important for them, water is going to be important for them. Making sure they have enough fluids to stay hydrated.
That excerpt of the most recent episode of the Short Talks from the Hill podcast features Rosie Perez, a PhD student in the Heat and Hydration Optimization Lab at the University of Arkansas, discussing her research with host Todd Price. If you'd like to learn more about Perez's work, you can visit kuaf.com/shorttalks.
Ozarks at Large transcripts are created on a rush deadline and edited for length and clarity. Copy editors utilize AI tools to review work. KUAF does not publish content created by AI. Please reach out to kuafinfo@uark.edu to report an issue. The audio version is the authoritative record of KUAF programming.
