It's that time of year when I go on a run and get so defeated by the humidity and heat that I wonder if I've made any progress the past year! The dramatic weekly changes in weather can be troubling when you workout - this blog post will give you info on the physiology of heat adaptation, and some tips on getting acclimatized and staying safe!
The Physiology
Our body is intuitively great at letting us know when it's uncomfortable due to heat. However, when we exercise we are using willpower to overcome those signals because you know that the body won't get stronger unless we challenge it at the edge of our current abilities. In warm weather we need to be especially mindful because there's a very thin line between challenging and over-doing it.
Luckily, these same principles of overload that make our muscles grow can be applied to our body's heat tolerance. And just as our muscles don't develop overnight, it takes 1-2 weeks of regular heat exposure to get used to changes in climate. What kind of adaptations does our body develop?
Sweating and breathing are our main tools to combat heat. As you adjust to warm weather, you should expect your body to sweat more than usual. Sweating is a good thing, but it comes with two other concerns: your water and electrolyte levels. There's no way around it - you gotta drink more water, but we'll cover more details about that below.
What about the salt? This highlights another beautiful bodily adaptation: as we acclimatize, our bodies learn to retain more electrolytes instead of sweating them out. We also develop Heat Shock Proteins to protect and heal our muscles more quickly against the inflammatory response of heatstroke. Our bloodstream also experiences improvements in the volume and flow rate through the heart.
Physiological Adaptations after Heat Acclimatization
You may be noticing that many of these adaptations are the same improvements seen when we undergo cardiovascular training, and it is true that by performing cardio workouts we can improve our heat tolerance. However, the research shows that blending heat exposure/acclimatization with cardiovascular training is the ideal path to higher heat tolerance. Once again, the balanced middle path is the best for our bodies!
How do we acclimatize? It can be as simple as spending occasional time in the heat, with the best acclimatization including some physical activity. For military and occupational purposes, 60-90 minutes of exposure + exertion is a standard program, but this may be unnecessary or impractical for the average gym goer. Our best recommendation is to keep living your life with mindfulness towards the weather, and be patient with the time required to get used to the heat.
Water
Let's take this opportunity to go over baseline recommendations for water consumption when exercising.
Drink 17-20 oz of water about 2 hours before exercising
Drink 7-10 oz every 10-20 minutes during exercise
Drink 16 oz for every pound of body weight lost during exercise
The last line may be the most important one - whether it's hot outside or not, you should directly replace all of of the fluids you lost during exercise. As we mentioned in the section above, you should expect your body to sweat even more as you become acclimatized, but the principle of replacing your lost fluids still stands.
For most people, a sports drink is not necessary except for very extreme or long-term exercise, however, the presence of electrolytes will help absorption of fluids, even if eaten independently from the drink. A few bites of salty snack is just as effective!
Clothing & Coverage
Intuitively you probably know what clothing to wear in hot weather - light colors, thin fabrics, and excellent wicking will help keep you cool. While no fabric will ever compare to the evaporative potential of bare skin, this brings up the important topic of sun coverage.
The sun adds considerable heat to our bodies, and sunburn decreases the body's ability to cool itself. Clothing should be your first choice for skin coverage, with sunscreen used to cover all exposed skin. Also consider head and eyewear.
Signs of Heat Exhaustion
Learn to recognize the signs of Heat Exhaustion and immediately take action to protect yourself. The next stop is Heat Stroke, which is much more difficult to recover from!
Heavy sweating
Muscle cramps
Fatigue
Weakness
Dizziness
Headache
Fainting
Nausea or vomiting
Dark urine
Cool, moist skin
Again, these are similar to the physiological responses to exercise and it would be easy to use your willpower to fight through the pain. Stay mindful and be in touch with your body!
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