Does Sweating More Mean You’re Getting a Better Workout? Not Quite

The typical satisfaction that comes from finishing a workout and finding yourself completely drenched in sweat at the end permits us to pat ourselves on the back. Your T-shirt is soaked through, your hair is unpleasantly sticking to your forehead, and you feel like you have earned the right to probably take a nice long break. It sort of feels like evidence that you have done something great for your body. Sweat can be treated as a fitness receipt more often than not. A dry workout, meanwhile, can leave you wondering if you pushed hard enough, if you maxed out your potential.

Except sweat does not keep score that way. “It is a myth. You do not burn more calories with more sweating,” says Jason Lee, an associate professor at the National University of Singapore who studies exercise physiology and heat. More sweat can accompany a difficult workout, but the two aren't interchangeable. Sweat is your body's response to heat, not a grading system for your exercise.

Sweat is your body's cooling system. When your muscles work, they produce heat. As your core temperature rises, your body sends blood towards the skin and activates your sweat glands. The sweat reaches your skin and, when it evaporates, takes some of that heat with it.

In less boring terms, your body isn't congratulating you on the quality of your squats- It's trying to keep you from overheating.

How much you sweat depends on plenty of things: temperature, humidity, clothing, body size, genetics, hydration and heat acclimatisation can all change how much you perspire. It's a very subjective thing. Two people can run the same distance at the same pace and finish looking like they have had entirely different workouts. That's no reason for the less sweaty person to feel bad about themselves. They might even feel a little happy to know that their hair isn't ruined for the rest of the day.

Humidity can make you feel considerably sweatier because the air is already holding a lot of moisture, which makes it harder for sweat to evaporate. And when you regularly exercise in the heat, your body can adapt by beginning to sweat sooner and producing more sweat. That is not a sign that you are working harder- It is one of the ways your body gets better at dealing with heat. 

The biggest misconception is that more sweat means more calories burned. It doesn't. The energy expenditure comes from the exercise itself, while sweating is the mechanism your body uses to cool down. A very sweaty workout can therefore burn fewer calories than a less sweaty one. You can also sweat heavily simply because you're sitting outside on a brutally hot day. The number on the weighing scale immediately after a sweaty workout can be misleading, too.

Any sudden drop is largely water loss, not a miraculous disappearance of body fat. This is also why deliberately trying to sweat more by wearing extra layers, using a sauna suit or exercising in excessive heat isn't a clever shortcut to weight loss. It can instead put additional strain on your cardiovascular system and increase the risk of dehydration and heat illness.

Then there is the idea that not sweating means you haven't worked hard enough. Strength training, lower-intensity endurance work and workouts in cooler environments can all be effective without leaving you looking like you've just walked out of a grease-fest. Heart rate, perceived exertion, strength, pace and your progress over time are far more useful ways to judge a workout.

Sweating is one of the body's most useful responses to exercise, particularly in hot weather. It helps prevent your core temperature from climbing too high, and becoming better at sweating can be part of your body's adaptation to heat. There is also that post-workout glow we all love.

What Your Sweat Is Actually Telling You

The more useful thing to take from a sweaty workout is that you have lost fluid and may need to replace it. How much you need depends on how long and intensely you are exercising, the conditions around you and how much you tend to sweat. During longer workouts in hot weather, hydration is particularly important, and electrolytes are your go-to when you are losing significant amounts of fluid and sodium.

Heat has an effect on your usual pace too- the five-kilometre run that comes easy in cooler weather might feel considerably harder in summer, and there is no prize for forcing your body to reproduce the same numbers in different conditions. If you feel dizzy, nauseated, unusually weak, or develop a headache or chills, stop exercising and get somewhere cooler. Heat illness is considerably less glamorous than a sweaty post-workout picture.

Maybe the better way to think about exercise instead of counting whether you looked like you had a good workout and start asking whether your body got what it needed from it. Did you lift a little more? Run a little farther? Build endurance? Recover better? Or simply get yourself moving on a day when you didn't feel like it? Those are much cooler measures of progress than how much sweat you can wring from your T-shirt. By all means, enjoy the glow. Enjoy the soaked-through shirt. Just don't mistake the puddle beneath you for a performance report.