07/20/2026
Each year about this time we field a lot of questions about the heat and with temperatures expected to hit over the century mark, this year is no different. So I thought it might be helpful to talk about how your system works in relationship to heat, how the body acclimates to the heat, and who is at increased risk for heat related problems and why.
In simple terms there are really three components to the bodies cooling system, the cardiovascular system, the skin and the sweat glands. The cardiovascular system role in cooling is two fold, dialating blood vessels close to the skin so that large volumes of blood carrying heat can get close to the surface and the heart that is responsible for pumping those large volumes of blood. The skin is the surface that moisture from the sweat glands gets pumped onto and then evaporates and carries heat with it - called evaporative cooling.
Now heat acclimation is a process that occurs when the body is routinely exposed to heat and helps us adapt to warmer temperatures. It occurs for most of us every spring as we go from wintertime body functions of doing everything possible to maintain heat to a posture of effeciently getting rid of it. For people who work in it or athletes that compete in hot environments there are really 3 things to help you acclimate - being in the heat (even a hot tub or sauna) for periods of time every day, exercising regularly and the best is a combination of those two, exercising in the heat every day for about 90 minutes.
What acclimation accomplishes in terms of your system is this. First it has effects on your heart and in a sense puts a governor on it and limits the high end of your heart rate so it doesn't go into the red zone when you overheat. It also makes in more efficient with more blood pumped with every beat. Acclimation also increases the bodies plasma and overall fluid levels, I call it expanding the sweat tank. This gives you more of reserve to use before you would get dehydrated and tank. Interesting enough and something I didn't know for a long time is that sweat glands are in a sense muscular and get out of shape in the winter months or when you are not exercising and using them on a regular basis. Acclimation gets them tuned up and in-shape. It also triggers the sweat glands and their discharge tubes and the kidneys to re-absorb salt which helps us maintain healthy fluid levels.
Now who is at risk for heat related problems. Well first people with underlying cardiovascular problems. If your ticker isn't strong enough to pump the volume of blood required to cool, you will overheat or put so much stress on the heart that you will be in trouble. Keep in mind that most activities that cause overheating are upright activities that is already straining the system. People on blood pressure medication and heart medications are also at risk. The way many of them work limits your heart function and may limit your circulation. Of course people who aren't acclimated are at risk and lastly just getting old has an effect on it. Age problems beyond your cardiovascular system are mostly related to your skin. Short version is this - skin thins as you age - tube of the sweat gland that travels from the base of the skin layer to the surface to carry sweat doesn't shrink. So when the skin shrinks that tube can get bent and twisted and we lose a lot of our sweat production.
So when it comes to heat and not getting in trouble from it, here is what I would say. If you can at least get out in some heat to trigger your body to adapt it will help. If you are never out of an airconditioned space expect that you will have problems. Stay in shape if you can, if your aren't acclimated be diligent about filling up the sweat tank with fluid and limit your time in the heat until you get acclimated. If you have underlying health issues or are on certain meds be careful. If you do overheat obviously get out of it and into the shade or a cool place and lay down if you get dizzy or feel like your are going to pass out.
Hope this is helpful and have a great rest of the summer!
