All About: The Heat

How our body reacts and the best ways to tackle the sun

Summer is here and we’re all entitled to have our fun under the sun. It is surely a necessary break for our anyone who endured a frigid winter. But whether you’re soaking up some rays in Disney, your friend’s backyard or the palm lined streets of Hawaii, one thing’s for sure, the higher temperatures put us all at risk for heat-related illnesses.

The heat carries along a spectrum of conditions that range from fainting and muscle cramps to heat exhaustion or heatstroke. Our body’s core temperature is normally maintained at around 37° C (98.6° F). However, exceeding 41°-43° C (105°–109° F), no matter the cause, can start to wreak damage to our bodies.

Our Body’s Response

The human body generates heat coming from the normal functioning of our cells. This increases when we do any sort of strenuous activity like exercising and when we get exposed to external sources of heat.

Thankfully, our body has it’s own central thermostat (yes, an AC unit if you will) located in our brain that triggers responses to counteract the heat. The most effective of these is sweating. The evaporation of moisture from our skin’s surface is responsible for cooling us down. However, at a humidity of 70% or more, this process becomes increasingly ineffective.

Another response method is the radiation of heat to the surrounding environment. This might get a little bit into physics but we do radiate away energy in the form of heat! Conversely, radiation is the major source of gaining heat in hot conditions. Think of our skin surface as a radiator that you’d find at home. The blood circulates from the inner most parts of the body closer to the surface so it can dissipate heat and cool our core. Essentially, the blood carries heat from our core to the skin surface where it can be cooled down.

Now you might be wondering how people in Sub-Saharan temperatures could survive their hellish environments? Well, unsurprisingly, our bodies can acclimate to these conditions that then allows it to lose heat more efficiently; but the process can require several weeks of exposure to warmer temperatures than you’re used to. Think of it as our internal thermostat being lowered gradually. It kicks off by sweating earlier and more wherein it can be as high as 1 to 2 liters an hour at times of heat stress! Blood flow also increases with a lower heart rate but bigger stroke volume meaning the heart pumps blood more efficiently per beat. All these adjustments combine to make our bodies make more acclimated to our surroundings.

Emergency Heat Conditions

Heat Syncope

Also known as collapsing or fainting after a period of heat stress. A snowballing effect of getting dehydrated and a decrease in blood pressure causes less blood returning to the heart, which means a decrease in blood going to other parts of the body such as the brain.

You’ll often see this occur when when someone standing in place under the sun for a long time suddenly collapses. In this condition, most people recover quickly with no problem after cooling and rehydrating. If they don’t, medical attention should be obtained immediately as it might be a sign of something more serious.

Heat Cramps

Consider this scenario: You’ve been walking all day along the river and enjoying your trip in Paris. You’re sweating profusely under the summer sun but you know all about the need to be hydrated. You reach for plain old water since you want to avoid the sugar in sports drinks too. You sit down at a café in Saint-Germain, relax and wait for your order but suddenly your calves start to painfully cramp and spasm. So what did you do wrong?

For starters, we would have probably done the same! Unfortunately, the cause of heat cramps is actually not that clear. But it seems to involve the depletion of electrolytes (e.g. sodium & potassium) and fluids at the cellular level. Our sweat doesn’t only contain water; it also contains a high amount of electrolytes or salt. In acclimated people, the composition of their sweat also changes wherein it contains fewer electrolytes.

If you couple the loss of these electrolytes in your sweat with drinking a lot of plain water, the concentration of these electrolytes in your bodily fluids becomes diluted. The end result is your muscles’ inability to relax that is dependent on a proper amount of these electrolytes.

Heat cramps aren’t a medical emergency and most people recover after rehydrating properly. There are electrolyte replacements available commercially either as liquids or dissolvable tablets that are more travel friendly!

Heat Exhaustion & Heatstroke

Now let’s tackle the two conditions that are more serious. The causes of these two are actually similar to those mentioned above: water and electrolyte loss due to heat. The symptoms of heat exhaustion also aren’t actually that specific but they typically involve the following:

• Heavy sweating
• Cold, pale, and clammy skin
• Fast but weak pulse
• Nausea
• Vomiting
• Fainting
• Body temperature is higher but < 40.5°C (105° F)

Since these symptoms are so similar to other conditions, like a stomach flu or infection, it is important to rule these out as well.

Some patients with heat exhaustion can progress to having a heatstroke even after removing them from the source of the heat. The main differences between the two are:

• Hot, red, dry (but possibly moist) skin
• Fast and strong pulse
• Rapid breathing
• Possible unconsciousness
• Loss of (mean arterial) blood pressure
• Body temperature > 40.5°C (105° F)

The loss of blood pressure then results with the loss of the body’s ability to radiate away heat from the inside. The core body temperature then dramatically increases. The consequences of heatstroke are:

• Kidney damage — due to lack of blood flowing to the kidney
• Liver damage—since liver cells are very heat sensitive
• Blood coagulation problems
• Multisystem organ failure — Blood supply is lost to other organs. Plus damage to other cells causes the release of inflammatory signals in the body

It goes without saying that any suspicion of heatstroke should be considered a medical emergency. Help should be sought out immediately so that the proper administration of fluids, cooling and any further resuscitation is accomplished.

Risk Factors

The following are the most at risk for succumbing to various heat illnesses:

1. The very old and very young

• The lack of mobility and communication can prevent them from cooling themselves and moving to a more comfortable location.
• The body also isn’t fully developed in young children to efficiently counteract the heat.

2. Not being acclimated to your surroundings

• As mentioned above, the body can adjust to your environment but it takes weeks to occur. If you happen to be vacationing or experiencing a heat wave, then the risk is higher.

3. Obesity

• Body fat acts as insulation and thus affects the way our body gets rid of heat.

The next factors go without further explanation:

4. Lacking adequate nutrition and hydration

5. Lack of access to air-conditioned environments

6. Exercising or working in the heat

Prevention

Stay Cool

1. If possible stay indoors and find air-conditioning
2. Avoid direct sunlight

• Stay in the shade or use an umbrella if going outdoors

3. Wear lightweight material

• Natural fabrics such as linen and cotton breath better versus synthetics like polyester

4. Wear light-colored clothing

• Light colors reflect the energy & heat from the sun while dark colors tend to absorb them

5. Take cool showers or baths

6. Use a moist towel and dab it on exposed parts of the body

• The neck and armpit areas are good areas to apply it as well

7. Exercise earlier in the day before it gets hot outside

Stay Hydrated

1. Drink more water than usual
2. Do not wait to drink fluids until you’re thirsty
3. Drink two to four cups of water every hour while outside
4. Eating a balanced diet should be enough for our electrolyte needs

• If more are needed, use lower sugar alternative sports drinks or electrolyte replacement therapy as mentioned above

5. Try to avoid alcohol and caffeine

• These can cause you to lose more water through urination

Stay Informed

1. Check the news for extreme weather conditions
2. Learn about the symptoms of these heat problems
3. Check up on those at risk and those living alone at least twice a day during periods of extreme temperature

At the end of the day, it is all about being aware and taking care of ourselves. Don’t let any of these conditions negatively impact what is supposed to be a relaxing time of the year. So go ahead and enjoy. It is the summer after all!

Have you or anyone you know experienced the wrath of the heat? Have some more info you’d love to share. Let us know by leaving a comment, tweeting us @irisapp or reaching out on Facebook.

This post is part of our “All About” series. Want to be informed when new posts like this and others go out? Be sure to sign up for our newsletter!