Understanding Exercising In The Heat

By: Dr. Goldberg (Invictus DC)

It’s common knowledge that exercising in the heat is hard; the heat has the ability to make just about any workout more challenging and, let’s face it, unenjoyable. Many, if not all, athletes may notice that their strength and/or aerobic capacity decreases in the heat as well, which can lead to frustration and, in some cases, exhaustion.

While it’s good and can be helpful to know that you’re not alone in this hot, humid experience, I find understanding the “why” behind it to be even moreso. So, let’s talk a little bit about why the heat makes working out feel so hard, and what, if anything, can we do to manage associated performance effects.

It may seem too obvious to be true, but the reason why working out in the heat is so hard is literally that our bodies get hot and can’t cool down. The process by which our bodies keep our temperature stable is called thermoregulation. It’s the need to keep our temperature stable that results in the performance impacts we experience in the heat.

Quick Review of Exercise Physiology

Before we get into how heat affects your workouts, let’s do a quick review on how our bodies responds to exercise in “normal”, or temperature-controlled environments.

The moment you start exercising, your sympathetic nervous system (which is responsible for “fight-or-flight” responses) is stimulated, resulting in various bodily responses that help keep you moving. A very high-level overview of some of these responses is below:

Challenges in Hot and Humid Conditions

Thermoregulation

Your body is like a thermostat, keeping your temperature within 1-2° of 98.6°F. This temperature range is really important to our survival, as it’s the safe range for all our organs and systems to function properly.

During exercise, the heat released by your working muscle results in increased body temperature. Your body has a couple of ways to release this heat:

Increased Blood Flow to the Skin: this brings heat from your core to the surface of your body, where it can be transferred into cooler surrounding air.
Sweating: heat is released as sweat it evaporates off your skin into cooler surrounding air

These “heat releasing systems” are normally effective, but when the air around our exercising bodies is excessively hot and/or humid, our bodies can’t effectively cool off and we start running into some issues. The resulting events happen simultaneously, and are illustrated below:

Dehydration

Fluid loss due to increased sweat rates during exercise puts athletes at risk of dehydration, which further exacerbates the performance effects above:

Dehydration leads to less fluid being available for heat loss via sweat
Progressive dehydration reduces exercising muscle blood flow, reducing their ability to continue working at higher intensities

Strategies to Mitigate Heat Effects

So with all this in mind, what can we, as athletes, do to mitigate some of these effects? Well, the unfortunate truth is that there’s only so much we can do.

Listen to Your Body

Hopefully by now you realize that the heat really does impact your athletic abilities! With that in mind, one of the most important mitigation strategies is simply to listen to your body.

- Set Realistic Goals: heat stress will reduce your body’s ability to achieve maximal aerobic capacity. Knowing this ahead of time can help you set realistic, heat-related goals

Know What Symptoms to Look Out For: feeling out of breath during a hard workout is normal and okay; feeling nauseous or dizzy, getting severe muscle cramps or chills, and noticing a reduction in your sweat rate is not!

Heat Acclimation

You’ve probably heard of heat acclimation, or the gradual build-up of tolerance to the heat. Our bodies are incredibly adaptable and, given time, our bodies can adapt to working out in the heat. Heat acclimation is super individualized, and it’s dependent on many factors like the duration and frequency of workouts and the environmental conditions of the day. In general, it takes at least 14 days for physiologic adaptations to take place and they go away once heat exposure ends.

Cooling Off

There are several easy and accessible ways to cool yourself down during your workouts. While these methods won’t negate all the heat-associated impacts, they can improve your performance:

Drinking cold fluids: this not only replenishes fluid lost in sweat, but can help lower your internal temperature
Cooling attire: cold or cool vests or towels, can help improve blood flow to exercising muscles

Hydration & Fuel

Before Your Workout: eating regular meals and snacks will provide your body with the fuel it needs to produce energy, while drinking water and electrolytes can help to decrease your risk of becoming dehydrated during workouts
During Workout: adding electrolytes and/or fast-digesting carbs can also keep you feeling good, especially during training sessions lasting longer than 30-60 minutes.
After Workout: ensuring you rehydrate and eat balanced meals post-workout will aid your body’s recovery after tough workouts

Conclusion

Exercising in the heat isn’t the most enjoyable experience for any of us, but understanding what’s happening inside your body can help you manage what you’re feeling and adapt to ensure you’re still getting in a great workout!

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