Heat, humidity, physical conditioning among considerations
Host Amber Smith: Upstate Medical University in Syracuse, New York, invites you to be The Informed Patient, with the podcast that features experts from Central New York's only academic medical center. I'm your host, Amber Smith.
More Central New Yorkers tend to be active outdoors in the warmer months, running, biking, kayaking, hiking. With exercise especially, sometimes it's tricky to know if we're pushing ourselves too much. Here to discuss warm-weather workouts is Upstate exercise physiologist Carol Sames.
Welcome back to "The Informed Patient," Dr. Sames.
Carol Sames, PhD: Thanks so much, Amber. Great to be here.
Host Amber Smith: Is there an outdoor temperature that's just too hot to be active in?
Carol Sames, PhD: Well, there's not necessarily a specific temperature because there's a lot of other conditions such as humidity, am I out in direct sunlight? The ground has conduction. If you've walked across hot asphalt on a summer day, you can feel that coming off. There's thermal, there's solar radiation. So all of that really impacts how we feel and what is a hot temperature for each individual.
Host Amber Smith: So it's all the conditions, but it's also dependent on the person themselves, it sounds like.
Carol Sames, PhD: Very much so. We could also have, like, how acclimatized am I to hot weather? Is it windy? And so, it's very difficult to say, "This is the temperature." There are people that can actually hit heatstroke, and it's been documented, in a marathon when the temperature was 43 degrees to start, but the humidity was quite high.
So therein lies the problem.
Host Amber Smith: So guidelines have got to be tricky for this.
Carol Sames, PhD: Yes.
Host Amber Smith: Workouts are meant to be strenuous and sweat-inducing, but of course we want to be safe about it. So how do we tell ourselves, or how do we learn, how hard to push?
Carol Sames, PhD: We all have to listen to our body, right? So if it's really hot, and I'm out there, and maybe I didn't really hydrate well, I'm out in the sun, I'm maybe running on some type of asphalt, and I start to feel, like, hot, and I start to feel maybe a little dizzy, and I'm just not feeling well. That's your body saying, "This is not the right situation for you."
You have to listen to your body. The body usually tells us, and it's just when we try to ignore our body that we generally run into issues.
Host Amber Smith: So you just have to be aware of the signs and symptoms you just gave us.
Carol Sames, PhD: Exactly.
Host Amber Smith: Now, during stretches of days where it's super hot for days on end, does it make more sense to try to work out in the early morning, when it might be cooler?
Carol Sames, PhD: Certainly that's an option. The way we protect ourselves and keep our body temperature low, the primary mechanism, is evaporation of sweat. So when sweat is rolling off of us, we are not evaporating. And if we're not evaporating, we're not cooling, because that evaporation is going to cool the blood that is at the surface.
When we're dripping, we're not evaporating. And so in the morning, usually the sun is lower, so you don't have that direct thermal heat on you, and it's usually cooler out. It could still be high humidity, but it's cooler, and so, we are able to evaporate.
Some people like later, like early evening.
And it's really just a matter of what fits into my time frame, and where am I going, et cetera. But generally speaking, unless you acclimatize to running at noontime in the summer, you're going to run into trouble. Yes, you can see people outside; I see noon runners all the time, but they have been doing that consistently. And so they have acclimatized to training, and there's actual changes that occur in the body that your body gets used to not producing as much salt-laden sweat. You tend to conserve. And we're also assuming these individuals are hydrating themselves properly before they go run at noon.
Host Amber Smith: I wanted to ask you about hydration. Is drinking extra water or the sports drinks, is that protective against heat injury?
Carol Sames, PhD: Absolutely, especially if you're going longer, right? Or it's high humidity. Water actually gets out of your stomach the quickest. But sports drinks usually have some electrolytes in them, sodium, chloride, those salts that we need. And some of the sports drinks also have a little bit of sugar in them. If you're out on a long, kind of arduous activity, after about two hours, you're running out of the stored energy that you have in your muscle and liver. And if you're not replenishing that, you're going to start to feel fatigued, and you're going to have to start using other energy sources, like fat. And when you start to use fat, it requires more oxygen, and it releases energy slower, so you're not going to be able to maintain the same performance.
So, having some type of replacement fluid, that if it's a longer distance or longer activity that also has some sugar in there, that can be really helpful to enable you to continue.
But with sugar, it's going to take just a little bit longer to get out of your stomach.
Host Amber Smith: Does the fabric of our clothing make a difference?
Carol Sames, PhD: It actually can, again, especially when it's hot. The old days, when we ran in 100% cotton clothing, when you start to sweat, it just sticks to you. In fact, it can hinder evaporation.
So, having clothing that is lighter in color, having clothing that is loose fitting, that's not tight fitting. because if you have tight-fitting clothing on, evaporation is hindered. Having clothing that has some of the newer materials that are very wicking, moisture wicking, can actually help with evaporation, so clothing really can matter.
Host Amber Smith: What about sun protection, and I'm thinking about sunscreens at the same time I'm thinking about hats or long sleeves? How does that play into keeping us safe when we're working out?
Carol Sames, PhD: So, a hat can be fantastic, keeping those direct sun rays off your head. I don't want the hat, though, to be so tight fitting that I can't evaporate off of my scalp, either.
But when I was younger, there was no sunscreen, right? Well, there probably was, but nobody used it. We used oil so that we could get a nice, nice tan, and we know now that that is the worst recommendation, that regardless of your skin tone, we can get sunburn, and that can lead to skin cancer.
We also know that excessive. outdoor exposure to sun can also exacerbate wrinkles. We can get sunspots. It's not healthy for the skin, so we want to use sunscreen, and we, if we're active, we also want to use sunscreen that is water resistant, because if you don't, it's just as soon as you start to sweat, it's rolling right off of you.
And apply liberally.
Host Amber Smith: Can you go over the symptoms and signs of heat illnesses and what to do if we start experiencing them?
Carol Sames, PhD: Yes. So, heat cramps are probably, if you've been out and you've done something that's fairly strenuous, you're used to heat cramps. It's almost like night cramps, where you have a muscle group, sometimes the calf muscle or the upper leg muscles, they just start to cramp. And it is very uncomfortable. Sometimes they'll continue to cramp. They won't relax. And that's a heat cramp, and really, it occurs because there's an imbalance between body fluid and electrolytes. What you need to do is stop, and you need to drink water or sports drink.
That should resolve. It's not going to resolve immediately, though. You're not going to just drink and be like, "Heat cramps are gone!" Most likely, what you're going to have to do is, if you were running, you're going to need to walk. If you were cycling, and it's bad enough, you're going to have to get off that bike. But that's what you need to do to resolve that situation.
The next two are what we consider more extreme heat illnesses. So, heat exhaustion, and that's when we don't have enough circulation to evaporate that heat that we're building up, and so, we start to lose blood volume, and we start to lose body volume.
In terms of "How do I know I'm kind of moving from heat cramps to heat exhaustion?" -- if I would take my pulse, it would be weak and very rapid. Usually when we're exercising, you can feel your pulse. It's nice and hard and steady. But with heat exhaustion, it's weak. You also might start to experience a headache because you're not getting enough blood flow to your brain, dizziness, and you just generally don't feel well.
You need to stop exercising. You need to move to a cooler location, under a tree, somewhere where there's shade. If you can get indoors where there's some type of air conditioning, that's even better, and you need to replace fluids. You might even need to go to the hospital and get an IV (intravenous fluids) -- kind of depends on how depleted you are.
The worst heat illness is heatstroke, and it is an immediate medical emergency. This is not something where people are like, "Should I go to the hospital or not?" because it's a cascade of events. Basically we have no more heat regulation going on, so we're no longer sweating. Our skin is hot to the touch. It is not moist anymore. Core temperature is at about 104 degrees or higher, and the body does not tolerate that type of extreme temperature. You end up with central nervous system failure, so a person might start to look very uncoordinated. All of a sudden, they can't stand. They may stumble and fall. You're starting to get organ failure, kidney failure, and people can progress really quickly from delirium to convulsions to coma. That's why this is a medical emergency. They need to get immediately to the hospital. They need to be immersed in cold water, ice, they need immediate fluid, IV immediately.
And you'd be surprised; even highly trained athletes have died from heatstroke. It is really problematic because when it starts, it's like a downhill car. It moves quickly.
Host Amber Smith: Can you tell when you have heatstroke, or do you not realize it, because that's part of the mental confusion?
Carol Sames, PhD: That's the problem.
That's why, like, at all major races there will be like race stewards. I can't speak for anything but running. I don't know if they have them out for cycling. Cycling, you usually don't get into that issue because you do have air currents because they're moving pretty quickly.
But you have to look at people, and if you start seeing people that it's warm out, and they're no longer sweating, usually a race steward would go up to them and kind of see. And if you feel that their skin is hot, you're going to pull them off the course. Do you remember the one female who was doing the Iron Man in Hawaii, and she was, like, a hundred meters from the finish, and she was just, like, all over the place, motor-wise, and she crashed, and she fell to the ground, and she was trying to get up, and she ended up getting disqualified because the medical team had to go out and get her? She was at heatstroke.
Host Amber Smith: This is Upstate's "The Informed Patient" podcast. I'm your host, Amber Smith, and I'm talking with Dr. Carol Sames. She's an exercise physiologist at Upstate, and our topic is warm-weather workouts.
We covered heatstroke, which is an emergency, but I'd like to talk now about another condition that can be very serious. Can you explain what rhabdomyolysis is? And I'm not even sure I'm pronouncing it right.
Carol Sames, PhD: That's the correct pronunciation. A lot of times we just call it "rhabdo." All it really is, is damage to skeletal muscle.
So, how can we damage skeletal muscle? Well, I could be in a car accident, and I have the steering wheel hit my legs, and I have damage to that muscle. It could be that I want to start an exercise program, and I'm really excited, and I just, I go "from zero to hero," and I go out, and I do some long activity, and I'm just not accustomed.
It could be that I have a lack of blood flow that could occur to muscles. It could be my electrolytes. I have sodium and potassium that I've become dehydrated, and that's a problem. There can be different diseases, like some muscle dystrophies. There's infections. It can be statin medications. Statin medications, a lot of us use to lower "bad" cholesterol. So there's a lot of reasons that you can develop what we call rhabdo. The thing that makes it challenging is, if I start to strength-train, and I've never lifted weights before, I'm going to have a little bit of rhabdo. I'm going to have delayed onset of muscle soreness.
Those muscles haven't been used before. And when we strength-train, we actually do have micro tears in muscle fibers; proteins are broken down. What sets that apart from clinically relevant rhabdo is that this is a normal physiological process; I'm going to have some soreness, but in a few days, that soreness is going to get less and less.
With clinical rhabdo, what happens is that you have serious damage, and that damage is extreme pain. A person will also notice, potentially, that they have very dark-colored urine. It is not straw colored. It's nowhere in the family of yellow. This is red-browns, and that's telling you: A, that I am probably dehydrated, but B, I have a protein that exists in skeletal muscle called myoglobin that is now being filtered through the kidneys, and it's coming out in my urine, and that is problematic.
Host Amber Smith: Are there things that increase a person's risk of developing this?
Carol Sames, PhD: The first known cases occurred in the military, where you had individuals maybe who weren't very trained, and they went into military training, or they wanted to do specialized training like the Navy SEALs or the Army Rangers, where they just had a dramatic increase in intensity of their activity. And that certainly can cause rhabdo.
Or you can have somebody, again, who's never been active at all, and they decide they want to become active, and they just do too much in a very short period of time. You see it more common in males versus females, and again, you can see it in low fitness and high fitness, so it can occur either way.
You also see it when people strength-train, when they do what we call more lengthening contractions. So if you go downstairs, OK, when you go downstairs, that is a lengthening contraction of quadriceps, and that can increase soreness. So for people maybe that are hiking, and they are not used to going downhill, if they've climbed, and now they start going down a long hill, a couple of miles of downhill, that could be rhabdo. It could be if it's a long enough hill, and they're going hard enough, they could experience that. And then, as I had mentioned, there's some genetic factors. There are certain diseases that can also predispose you to that.
Host Amber Smith: Does heat or a high temperature outdoors, does that bring it on quicker, or does it influence it in any way?
Carol Sames, PhD: It absolutely does because it's dehydration, right? And so, once we start to become dehydrated, we run into all kinds of problems. The kidneys aren't happy. We can't clear that muscle protein and other toxic substances, and then what happens is, we start to have reduced blood flow to the muscle, and the muscle is trying to work.
We can also get swelling. And then that can lead to compartment syndrome, and so, again, it can be a cascade of events that occurs, and really the concern is kidney failure because if somebody has rhabdo, pretty serious rhabdo -- and there's some blood markers that you can use to check -- if that is not reversed with an IV, a specific IV with some bicarbonate, you can have damage to your kidneys, and we don't want to damage our kidneys because that can lead to a whole other set of problems.
Host Amber Smith: Well, you've kind of talked about some of the signs and symptoms, the very dark-colored urine, the muscle soreness or pain. Are there other signs and symptoms that would make a person think, "Oh, maybe this is more serious. Maybe it's rhabdo"?
Carol Sames, PhD: Your soreness is not dissipating with time, like it is extreme pain that is not getting better.
Again, delayed-onset muscle soreness, which is normal, is going to dissipate over days. Rhabdo is not. Once you start having more than one episode of urine, That's the sign, "I need to get checked out. There's something that's not right here."
And I did mention compartment syndrome can happen because when we start to have lack of blood flow to muscle, that's problematic. That means we're not getting oxygen to muscle. We don't get oxygen to muscle, muscles are not going to contract well, they're not going to move. And you're going to start to experience those symptoms also. It's kind of really like a vicious cycle of tissue death that goes on long enough, you have more and more areas of muscle that are dying, and you're going to know that. You're not going to be able to move. You're going to be in extraordinary levels of pain.
Host Amber Smith: So compartment syndrome is equivalent to muscle or tissue death? Is that what is happening?
Carol Sames, PhD: If you don't do anything about it, yes. And rhabdo can bring on compartment syndrome, but compartment syndrome can also come on without rhabdo. OK, so people that tend to engage in activities that are high intensity, running, a lot of jumping types of activities, what can happen is that muscles are surrounded by, like, connective tissue and as that muscle expands, that connective tissue might not expand. And so, there is pressure there, which means we have less blood flow because the pressure is getting higher, and when you have less blood flow, you're going to have tissue death. And so what happens is the person will note, and again, you can see this with individuals, maybe they're starting the beginning of a sports season, and they're not quite really in shape, and the intensity is high, they're doing a lot of activity. They can develop this compartment syndrome. It's not uncommon to occur in the lower leg. And when they stop, it goes away. But over time, it can become so painful, it interferes with the ability to continue whatever activity that is.
There is treatment. You can cut the connective tissue to allow the muscle to swell without restriction, so the blood can flow. Now, clearly, that's extreme, but that would be the case if it wouldn't resolve on its own.
Host Amber Smith: Well, I think I understood you to say that rhabdo can be diagnosed with a blood test, and then it can be treated with, did you say bicarbonate in an IV?
Carol Sames, PhD: So that's what you can do with, like, an acute case of rhabdo. Chronic is more like compartment syndrome, so that compartment syndrome is more of a chronic, it doesn't, like, just come on today. Whereas rhabdo could, if I was completely untrained, and I did something that was extraordinarily intensive for a period of time, I could develop rhabdo fairly quickly, in a day, and especially if I tried to do the same thing tomorrow.
With more chronic compartment syndrome, you can have a special MRI (magnetic resonance imagine scan) that can look at the pressure that exists in the muscle group. And if that pressure is high, then that's telling you blood flow is restricted. You can look at blood flow through there. If you see that it's reduced, most likely the pressure would be higher.
Host Amber Smith: Is there anything people can do proactively to prevent or even just reduce the risk of rhabdo?
Carol Sames, PhD: First of all, know, again, what your limits are, right? So, like, you can't go from zero to hero. If I've not been active, I need to know that it's going to be a slow and steady progress. I need to make sure that I'm not dehydrated, and that I'm taking in enough fluid.
So that might mean if I'm out doing an activity, that I bring water, sports drink, with me, or that I have stops along the way where I can drink. In terms of older adults, it's very important to understand that we lose a thirst drive as we get older. Essentially, what we say is that after the age of 65, almost every adult is dehydrated, to start.
So, if you're dehydrated to start, and then you go out, and it's warm, and you're exercising, you're becoming even more at risk of dehydration, and then, kind of that cascade of heat illness. So, that's really important.
I just really think it's always good to carry something with you, some kind of fluid. You never know, especially if you're going to go out, you don't really know how hot it's going to get. If you're going out to a new area, you don't know where the shade is, all of those things that if it's an area that you're more comfortable with, that you walk or run or bike that you're familiar with, there may be areas where there are stops where it's shaded.
If it's a hot day, and there's no wind at all, and it's humid, you need to be smart. You want to make sure you have proper clothing. I might want to have a hat on. I have fluids with me. I might want to be with somebody, or I might want to go to an area where there are other people, that I'm not completely isolated.
There's a reason why I, personally, run in the morning. I don't heat-acclimatize well. I don't feel good in the heat, and so I would much rather get up in the morning before it gets really hot and just get something done. I'm impressed by those noon runners, but it could never be me.
Host Amber Smith: Well, before we wrap up, let's go over what people can do to stay safe in the heat when they're active. You've already talked a little bit about the type of clothing and the fabric being more moisture wicking and less cotton, and to prepare with adequate fluid or bring fluid with you. Is there anything to eat or drink before or after, for recovery or for preparation?
Carol Sames, PhD: So, definitely water leaves the stomach quicker, so water is going to be the quickest coming out. If you know you're going to be doing something that's longer duration, again, if you start to talk about higher intensities, longer durations, you probably are going to want to have some type of fast-acting sugar with you, whether it be chews, or there's goos, there's all kinds of things out there. You probably are going to want that if you want to maintain that same intensity. I always suggest that.
You want to make sure sunscreen is on, if you're going to be out in the sun, because all of us have experienced what it's like to burn. And I want to make sure that my clothing is appropriate.
I always tend to like, if I'm going to do something that's a little bit more strenuous, to do a loop type of activity so that I know I'm coming back to civilization. Just in case, because you never know what can happen until you experience something like heat cramps, where you know you're in trouble. It's always nice to be closer to civilization.
It's also good to practice with this, to not just go out the first time and go, "I'm going to take chews, or I'm going to take all this water, and I'm going to be fine," because some people, it takes an adjustment for their stomach to kind of get used to food or water slashing around when you're doing an activity. For some people that's not comfortable. So it's best to practice that.
And I think, you know, it comes down to what's common sense. And in Central New York, our weather changes quite rapidly. Something else: In the summer, it's not unusual potentially to have a storm coming. So, all those want to take into account, especially if you're going to be out for more than, like, 20, 30 minutes.
Host Amber Smith: Are you able to make your own sports drinks or, chews to save money? I mean, those can kind of add up.
Carol Sames, PhD: Yeah, they are.
I have seen people use cornstarch. There are recipes out there where you can put a flavor into cornstarch, and it will solidify. It's very fast-acting glucose, and certainly, that would work.
And there are some things that you can, like, sprinkle into (water), so I know that Gatorade has a powder format that you can throw into a drink, so its cost per unit is cheaper, so you still are getting those electrolytes, again, if you're going to be out for a while, or it's really kind of warm and humid. So there certainly are options for that.
I'm speaking from experience because, yes, I have crashed before. It's a terrible feeling. I've experienced heat cramps before. It's just not a good feeling that you want to get yourself into.
Host Amber Smith: When it is super hot, is swimming or rowing, is that a safer activity because you're on water or not necessarily?
Carol Sames, PhD: It certainly can be.
The thing with swimming is, if you're going to be swimming, depending on what kind of suit you have, if you're a guy or a girl, you can burn on your back. Sometimes people are thinking, "I'm under the water, I'm not going to burn." It's a little bit different than if you have a whole shirt on.
So it's just something to think about. But, yes, swimmers do sweat. They still evaporate heat in the water. Sometimes people are, like, "They don't sweat." Yes, they do. You just can't quite see it because they're already wet.
Rowing also can be wonderful, but again, make sure that sunscreen is on.
And some days there's just not any wind current out on a water source. Wind is always really helpful when it's hot, because at least it helps with evaporation.
Host Amber Smith: I know especially runners and bicyclists, they like to kind of train on their own. When conditions are severe, in terms of heat, would you recommend to have someone nearby or at least let someone know where they're headed?
Carol Sames, PhD: Personally, I think that's a great idea. And I would also say if somebody is not highly trained, it might just be a day where you say, can I do something at home? Do I have any equipment at home, or am I a member at a (gym) facility? Like, maybe today is not the day.
I think, probably, if I look back on my bad experiences, I had plenty of signs to tell me, but I ignored them all. And the problem is, you ignore these signs, and then you end up in difficulty. And so, if I had an older adult, and they were saying, "It's hot and humid, I really want to get my walk in," can I go to the mall? Can I go somewhere, do I have the ability to do that? And if not, can I do something at home? So, can I go up and down the stairs in my house? Can I set up a little high-intensity interval training workout in my home? Because it might just be a safer option for me. It's just always great to be proactive. Retroactive is not always the best way to go. You can run into some serious dehydration quickly.
Host Amber Smith: Dr. Sames, thank you so much for sharing this advice.
Carol Sames, PhD: My pleasure. Thanks so much for inviting me, Amber.
Host Amber Smith: My guest has been Upstate exercise physiologist Dr. Carol Sames.
"The Informed Patient" is a podcast covering health, science and medicine, brought to you by Upstate Medical University in Syracuse, New York, and produced by Jim Howe.
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