Sept. 20, 2018

Why it's OK to stay sweaty after a workout

Kinesiology researcher Tish Doyle-Baker on perspiration
Tish Doyle-Baker, professor in the Human Performance Lab in the University of Calgary's Faculty of Kinesiology, spoke about the Science of Sweat in mid-September during Beakerhead, a Calgary festival of art, science and engineering.
Tish Doyle-Baker, professor in the Human Performance Lab in the Faculty of Kinesiology. Riley Brandt, University of Calgary

Whether you like to call it glowing, spritzing or perspiring, we all do it. We all sweat. But we don’t all understand why.

“Sweat exists to maintain your body’s temperature as close as possible to normal, which is 98.6 degrees F (37 C),” says Dr. Tish Doyle-Baker, DrPH, professor in the Human Performance Lab in the Faculty of Kinesiology. She spilled all about the Science of Sweat during the 2018 edition of Beakerhead, a Calgary festival of art, science and engineering.

Sweating is part of a complex system that kicks in when you use your muscles. Whether you’re walking the dog or running a marathon, when your muscles get going they need more oxygen.

“During exercise, your heart rate picks up and the increased blood flow amps up the delivery of oxygen to your working muscles,” says Doyle-Baker. “That increases your temperature, triggering your sweat glands.” They pump out moisture to your skin. It evaporates, cooling you down.

Sweat is made up of about 99 per cent water and one per cent salt, potassium and carbohydrates. How much you sweat depends on a number of factors, including your genes and your fitness level. An average person doing an hour of exercise produces about a litre of sweat.

If you’re really fit you will start sweating earlier in your workout and produce more sweat. You’ll also produce more heat shock proteins, a handy compound for fighting inflammation. “The more you exercise, the more these heat shock proteins come into play,” says Doyle-Baker. “When you sweat they respond to safeguard other proteins from damage, repair damaged ones and they can also signal to produce new healthy proteins.”

Your body uses salt to help draw the water out of your cells and turn it into sweat. That’s why sweat tastes salty and you may see white salt streaks on your gym clothes. You don’t want to lose too much sodium, or electrolytes, because they maintain the amount of water in your blood and in and around your cells.

The more you sweat, the more you need to replenish your body with fluids. But stay away from gulping down sports drinks. It’s better to sip plain old water, says Doyle-Baker. “Hydrate before exercise and along the way because it’s easier for your body to adjust than when you take huge amounts of water in at one time. When you do that, the water all has to go into your stomach and then your body has to make sure it’s at the right temperature before it can make use of it.”

Sweat also produces oil that protects skin from drying out. That’s what causes that sweaty smell. But take your time getting to the shower after working out because sweat has little superpower “killing invaders,” says Doyle-Baker. “Sweat is designed to guard against infection. It’s like a natural antibiotic and protects us from really harmful pathogens like E.coli and some strains of staph (Staphylococcus aureus).”

So rejoice in your sweat because science shows that “your body is better off the more frequently you sweat.”