Is Sweat Really a Reliable Way to Measure Exercise Intensity?

One of the most sought after things in the fitness world is an accurate way to measure exercise intensity. People look to muscle soreness, exhaustion and all sorts of other tools, both absolute and relative to make sure they’re working out hard enough. A common feeling is that if you aren’t sweating, you are going to burn calories or reduce body fat. But is sweat really a useful and accurate way to judge workout intensity? A look at the purpose of sweat, as well as some of factors that effect how much we sweat can help decide whether or not sweat is useful for this vital part of out workout design.


Why Do We Sweat?

The human body has several ways to maintain a healthy internal temperature. Radiation is used to release heat through the skin into the air when the environment around you is cooler than your body.

Conduction is a direct transfer of heat when you make contact with a cooler object, like swimming in cold water.

Convection occurs when cool air, like from a fan, passes over your skin.

The method that we’re looking at here is evaporation, in which sweat plays a key role. Evaporation is perfect for situations in which the environment is hotter than your internal temperature. This happens when your hypothalamus reacts to a rise in temperature by activating the sweat glands that cover your skin. These glands produce sweat, which absorbs the heat from your body and rests on the surface of the skin. When the sweat evaporates, you feel cooled.



Whether we’re aware of it or not, we are constantly sweating and producing heat. Logically, our temperature rises when we exercise. But, much more than exercise controls the amount of sweat our body produces. Age, gender and fitness level all have a bearing on how much you’ll sweat. The most powerful factor that affects our sweat levels, however, is the environment.

As mentioned, we sweat when the air around us is hotter than we are. When the air is humid, though, the sweat cannot evaporate. It collects on the skin until it begins to drip, giving the appearance of excessive sweating.

Sweat, then, is simply the chosen method for lowering your body temperature in a hot environment.


Listen To Your Body

Sweat, especially excessive sweat, is a signal that your body is struggling to control it’s temperature and that you’re in danger of overheating and dehydrating. Try not to exercise in extremely hot and humid environments, since sweat can’t do it’s job under these conditions.

Also, it’s always important to stay hydrated. Generally, the recommendations for hydration are to drink 1 to 2 cups of water two hours before exercising, a half cup to a cup during and 2 1/2 cups in the half hour following exercise.

Of course, everyone is different and you should listen to your body. Drink when you’re thirsty and stop exercising if you feel dizzy and/or have trouble breathing.

Sweat is, ultimately, an unreliable way to measure how hard you’re working out. Other methods, like rating your exertion on a scale of 1 to 10, while relative, can be much more useful.





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About jonathan.thompson

Jonathan Thompson is a Certified Personal Trainer and Running Coach with the American Council on Exercise, specializing in nutrition. In addition to his real-world experience working with clients, his articles and blogs on fitness advice have been published on many websites and magazines.