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Ep. 40 – Heat stress risk

Heat waves and extreme weather are becoming common place these days, so is the risk of heat stress. Who is most at risk and why? What can we do about it? Dr. Chet addresses those questions and more on this edition of Straight Talk on Health

Welcome to Straight Talk on Health. I’m your host Dr. Chet Zelasko. Straight Talk on Health is recorded in conjunction with WGVU in Grand Rapids MI. I examine the world of health. Whether it’s research that makes the news, another miracle diet, or a new food fad, I look at the science behind them, and let you know whether it’s real or not. You can check out other things that I do on my website drchet.com and sign up for my free emails.

I don’t know exactly when it happened—suddenly I just don’t seem to sweat when I exercise. Disappointing, because it was something that I looked forward to, believe it or not. To me, it symbolized getting a good workout, whether during exercise or working in the yard. Why is it a big deal? It means one of my cooling mechanisms isn’t working well while I'm exercising. And it isn't only during exercise. It also seems to happen in the heat. It’s not uncommon in people past middle age. How about you? Have you noticed any changes?

I’m not alone in this age demographic. There’s another at-risk group: babies and children, especially during the kind of heat we’re facing in many areas of the country in the summer of 2023. There are two questions I wanted answers to. First, why are these two groups more at risk than others? The second question is actually twofold: how do we know when someone is under heat stress, especially when they can't communicate very well as babies and some elderly, and two, what can we do to reduce the risk of heat stress.

Let's start with the why. There appear to be two problems: there’s little to no research on the heat response in the young and the old with one exception: during exercise. Secondly, it's a topic that doesn’t seem to attract much attention. With the heat rising, I expect we'll see more focus on the mechanisms of cooling in these age groups

Let’s turn to basic physiology to get some answers. Research has found that the reason these age groups produce less sweat relates to the lack of development and the impact of aging. The very young haven’t yet developed their skin’s sweating mechanism, but it improves as they continue to develop.

So the solution for infants and children is really nothing more than continued development. I'll save you the details of what happens physiologically because the why is always more complex.

The problem as we age is that our skin declines, along with other physiological mechanisms. Our skin gets thinner and loses sweat glands. Our heart doesn’t pump as much blood nor pump it very efficiently. Complicating things is that a majority of people over 65 years carry excess body fat which also strains the cardiovascular system. Every metabolic disease like an under active thyroid and diabetes strain the cooling system. At some point, that strain and lack of functioning sweat glands reduces our ability to cool our bodies via sweating in the heat.

While everyone is at risk, especially those that work in the heat and humidity, children and those 65 and older are more at risk because, as I suggested, one of their cooling mechanisms is not working effectively. Let's look at signs and symptoms of heat stress as well as solutions.

Let's begin with infants and children. Here is a list of signs and symptoms of heat stress. They may not all happen within the same child at the same time but they should raise awareness that it may be heat related rather than a typical fatigue or possible infection response.

An elevated body temperature, usually between 100˚ and 104˚F. I don't think I would have suspected to check internal body temperature to see if internal cooling mechanisms were working. Especially if they were experiencing the next couple of signs and symptoms. Those would be cool, clammy skin and goose bumps. Those seem more related to being too cool rather than too hot. So checking the internal temperature it's a good idea.

Irritability, increased sweating and increased thirst are also signs or symptoms of heat stress. But again, there can be other reasons such as lack of sleep or hunger.

Then we get into a list of signs and symptoms that should raise alarm bells. They include:

Fainting, dizziness or weakness


Muscle cramps

Nausea and/or vomiting

It may be difficult for babies and children who are just learning to talk to communicate a headache or even muscle cramps. But I think we would all recognize that fainting dizziness and weakness or vomiting for sure, means something is not quite right.

Let's turn to signs or symptoms in those who are older, generally 60 and older. There are some similarities with the young. While the young may not be able to communicate effectively because they haven't learned how to talk yet, those that are older tend to ignore symptoms that may be related to heat stress. With that in mind, here are the signs and symptoms of heat stress.

Heavy sweating If they are fortunate to still have an operating sweat cooling system. If not, they may have cold, pale, and clammy skin.

A fast, weak pulse may go along with the cold and clammy skin as the heart is working harder to pump blood to the skin for cooling. Muscle cramps may also be common at this point.

Then we get into the symptoms that don't require a lot of communication just like with children. Those symptoms are nausea or vomiting

Tiredness or weakness



Fainting (passing out)

As you can see, there are many similarities in symptoms between the young and the old. The difference in what causes the symptoms is that the children’s systems are developing while the adult’s systems are degenerating.

I found the term, Heat Action Plan for the At Risk, while combing through the background research. The most common recommendations are stay in the air-conditioned indoors if possible. If not, still indoors, preferably with fans. Another is to drink liquids. Mostly water but depending on sweating, a sports drink has electrolytes which can also be lost while sweating. Too much plain water can dilute electrolyte balance and cause hyponatremia, the lack of sodium in the body.

If you don’t have to go outdoors, don’t. If it can’t be avoided, do it in the early mornings or the evenings. From the Midwest to the East coast, we also have to deal with air quality due to the fires in upper Canada. Again, staying indoors and out of the sun is still a great prevention strategy.

Finally, observation is critical with both children and older adults. it’s nice when the house is quiet but some children are not old enough to tell you what’s wrong or just don’t know whether what they are feeling is normal or not. Observe them. It also applies to the older adults in your life. Check in with them frequently to make sure they are doing okay.

What happens if you suspect heat stress? Check it out. Cool baths or showers. As few clothes as is realistic. Drink cold fluids. Ice compresses at critical spots like the sides of the neck and inner thighs. But by the time you get to the symptoms of dizziness, weakness, or fainting, time for a visit to the ER. We can deal with the heat if we just play it smart--and we look out for each other. Until next time this is Dr. Chet Zelasko saying health is a choice people. Choose wisely today and every day.


1. Eur J Appl Physiol. 2018 Oct;118(10):2233-2240.

2. J Athl Train. 2021 Aug; 56(8): 801–802.

3. https://www.cdc.gov/disasters/extremeheat/heat_guide.html

Dr. Chet Zelasko is a scientist, speaker, and author. Dr. Chet has a Ph.D. and MA in Exercise Physiology and Health Education from Michigan State University and a BS in Physical Education from Canisius College. He’s certified by the American College of Sports Medicine as a Health and Fitness Specialist, belongs to the American Society of Nutrition, and has conducted research and been published in peer-reviewed journals. You can find him online at drchet.com.
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