If you’ve ever taken part in a hot yoga class, or worked out when it’s really hot outside, you know it can get pretty messy… with sweat, that is! You may feel it’s a bit gross, but all your body is trying to do is to adapt to the soaring temperatures and keep your internal temperature stable.
Maybe you don’t even think about your sweat aside from needing to remember to take the necessary precautions against it’s messiness; like bringing an absorbent towel to yoga to avoid soaking the floor of the studio or wearing a sweatband to prevent the sting of perspiration from ruining your outdoor exercise session.
The truth is, it’s a super important safety mechanisms your body has in place, and without it, you would end up a heap on the floor, and not because you’ve had a great workout. Let’s try to prevent that, shall we?
Heat adjustment during exercise
When you begin to exercise, your body produces heat. It’s how you perform.
If you exercise in a hot environment on top of that, the demand for cooling the body and keeping core temperatures within a small and strict range, becomes a big priority. The first way the body does this is by producing sweat1,2.
Think about the way you use water in your home to cool things down; your body is essentially trying to do the same thing.
Your body’s cooling system, however, comes from fluid that actually contributes to your overall blood volume. It’s simply the most easily accessible fluid, which the body sends to the surface of the skin to aid in generalized body surface area cooling. When the fluid shifts out of the body through sweat, it causes a decrease in overall blood volume. Now, this isn’t generally a problem... in most cases. Typically your body replenishes this lost fluid from other areas, like from your cells and non-essential organs, and from the water you consume by drinking it or eating foods higher in fluid.
The trouble comes in when you’re already slightly dehydrated, meaning there’s less water to move around, and you place a higher demand on this cooling system by working out in the heat3. You’ll notice this as the fatigue you start to feel as you progress through the exercise routine, as the heaviness in your legs, and as the feeling of your head being a little swirly4.
If you were to continue to exercise without replenishing fluid, the symptoms would get worse, you may start to feel nauseated, and you’ll likely need to stop working out5.
Continue to keep it up, and your body will begin to struggle to maintain a stable core temperature, and you may actually stop sweating at this stage, which is the body’s way of saying, “there’s no more water to give!”. It may, however, compound the problem as you’re no longer getting the cooling effect from the outside.
Heat stroke is no joke; it can be fatal6.
That’s where we begin with the tips on how to avoid it.
Adapting to exercising in the heat1. Give yourself time to adapt
If you’re planning to exercise more outdoors as it gets hotter, be sure to start off slowly. It can take several weeks for your body to adapt, and allowing this process to take place naturally and without causing unnecessary stress to your system7,8.
Even seasoned athletes take time to train themselves to be heat adapted!2. Improve your fitness
The fitter you are, the better your body will be at becoming heat adapted. Fitter athletes who have lower resting heart rates may better handle heat stress than those who are less fit and who have a higher resting heart rate.
Be sure to take part in exercises to improve your cardiovascular fitness such as running, for example, in cooler environments when you start out.3. Hydrate!
Never take the amount of water your body needs to function for granted, especially if you are active. You may lose 1-1.5l of water for every hour of exercise you do9.
That being said, there’s much debate around the 8-glasses-of-water-a-day ‘rule’, and why it doesn’t meet the needs for those who exercise regularly or who live in hotter climates. Closer to 3 liters of 12 glasses of water a day may be more effective, where sipping it throughout the day is more valuable than gulping it down before or after exercise.
Don’t forget to replenish the salts like potassium, sodium, chloride, calcium and magnesium that you also lose as part of your sweat10,11.4. Adjust the temperature of your environment
Being able to sit in your air-conditioned car, office or home may be the relief you need from sweltering outside temperatures, however, if you’re trying to become heat adapted, it may not be doing you much good as your body has to adjust to these extremes in temperature between your indoor and outdoor environment.
Instead, set your indoor temperature to no lower than 10 degrees below the outside temperature; of course you may do this over several days or weeks until your body adjusts.
When you know that sweating is actually a safety mechanism and an indicator that your body is working as it should, it loses some of it’s less appealing stigma, doesn’t it? So, go ahead, get out there and sweat; just do it responsibly using the above-mentioned tips!
- Tyler, C., et al. The effect of cooling prior to and during exercise on exercise performance and capacity in the heat: a meta-analysis. Br J Sports Med. 2015 Jan;49(1):7-13.
- Taylor, N. Human heat adaptation. Compr Physiol. 2014 Jan;4(1):325-65.
- Akerman, A., et al. Heat stress and dehydration in adapting for performance: Good, bad, both, or neither? Temperature (Austin). 2016; 3(3): 412–436.
- Cheung, S., & Sleivert, G. Multiple triggers for hyperthermic fatigue and exhaustion. Exerc Sport Sci Rev. 2004 Jul;32(3):100-6.
- Racinais, S., et al. Consensus recommendations on training and competing in the heat. Scand J Med Sci Sports. 2015 Jun;25 Suppl 1:6-19.
- Periard, J., et al. Adaptations and mechanisms of human heat acclimation: Applications for competitive athletes and sports. Scand J Med Sci Sports. 2015 Jun;25 Suppl 1:20-38.
- Tyler, C., et al. The Effects of Heat Adaptation on Physiology, Perception and Exercise Performance in the Heat: A Meta-Analysis. Sports Med (2016) 46:1699.
- Guy, J., et al. Adaptation to hot environmental conditions: an exploration of the performance basis, procedures and future directions to optimise opportunities for elite athletes. Sports Med. 2015 Mar;45(3):303-11.
- Epstein, Y., & Moran, D. 44 - Extremes of Temperature and Hydration. Travel Medicine (Fourth Edition). 2019. 407-415
- Sawka, M., et al. Integrated physiological mechanisms of exercise performance, adaptation, and maladaptation to heat stress. Compr Physiol. 2011 Oct;1(4):1883-928.
- Baker, L. Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability. Sports Med. 2017; 47(Suppl 1): 111–128.