The Value of Sweating and Hydrating

Sweating And Hydrating

Sweating is our body’s natural cooling system. It keeps our temperature in check working on an automatic internal thermostat. I like to think of our pores as the permanent filters in the system providing the opening for sweat to be released. Is there more to sweating than what’s obvious? And how much should we be hydrating when we do?

Cooling System

Sweat is a combination of water and salt. “When sweat evaporates from your skin, it removes excess heat and cools you…When the water in the sweat evaporates, it leaves the salts (sodium, chloride, and potassium) behind on your skin, which is why your skin tastes salty,” Craig Freudenrich, Ph.D. wrote in How Stuff Works. “The loss of excessive amounts of salt and water from your body can quickly dehydrate you.”

We have a serious number of sweat glands and the amount varies by gender. In an August 2013 Huffington Post article Six Things You Didn’t Know About Sweat reported that each of us has two to four million sweat glands. Although women have more sweat glands than men, men produce more sweat. The article also states that an athlete who exercises intensely in the heat can sweat out 2-6% of their body weight.

We all sweat at different degrees. How quickly someone sweats is not necessarily, a sign of their fitness level. Although, many exercise enthusiasts measure the value of their workout by how much they sweat.

Sweat and yoga are a package deal in hot yoga classes. The classes are held in a room with temperatures hovering close to 100 degrees Fahrenheit, sometimes higher. It’s not uncommon to see the yogis leaving class dripping in sweat with red faces.

Fitness pros and trainers know sweating is part of the workout– a by-product. But hydration needs to accompany a measurable amount of perspiration.


Hydration is paramount. The more you sweat, the more you need to hydrate. Total body weight is an estimated 60% water, according to the NFPT manual. In addition to regulating body temps, water also assists with internal chemical reactions like digestion, circulation, and waste excretion.

The amount of water needed to hydrate varies based on factors such as air temperature, humidity, clothing, diet, exercise intensity, and individual needs. There are various opinions on how much fluid we need, but it’s usually between 8 and 10 cups of water daily. Always heed your medical professional’s advice!

When exercising, NFPT recommends drinking water throughout your workout as well as following it. The small intestine absorbs 8 – 10 ounces of water every 20 minutes, so you want to pace your fluid intake. I remember as a sprinter waiting until the end of the meet to down a large bottle of a sports drink, only to throw it up in a trash can. Now I know why!

Drinking as you’re actively sweating gives your body a chance to use it on demand, rather than guzzling a bunch at once. I see many gym-goers walking around with a gallon jug of water to help them measure how much they drink.

Weighing before and after a workout can be a quick estimate of how much fluid was lost. To replace lost fluids, you need to ingest 16 ounces of water for every pound lost.

Water or Sports Drink?

When do you need a sports drink, instead of water? NFPT recommends a sports drink of 6-8% sugar solution with 100 mgs/8 OZs of sodium concentration if exercise is intense or lasts more than an hour.

I like to think of water for my body like gasoline for my car. It keeps my motor running. In fact, oftentimes, people think they are hungry when they are thirsty.

Sweat is going to happen. “Sweat cleanses from the inside,” said Dr. George Sheehan. “It comes from places a shower will never reach.” As trainers, we can continue to emphasize sweat and hydration benefits. And whether to hydrate with water, water alternatives, or sports drink.


Personal Fitness Training Manual, National Federation of Professional Trainers, 7th edition, page 146 (2017).


Kim Becknell Williams is a freelance writer with more than ten years of personal training experience. Certified through NFPT, she is a Functional Training Specialist and holds a Master Trainer level certificate for resistance, endurance and sports nutrition. Kim has written two books including Gym Etiquette 101. She enjoys writing a variety of lifestyle articles and fitness blogs.
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