I don’t know about you but I can’t step outside without wearing my body’s very own brand of tears. My sweat glands are constantly weeping for the respite of a cool, heat-repelling climate that Singapore naturally lacks – then reminds me again with the stickiness of a thousand Post-It notes after the perspiration has dried off.
But as uncomfortable as it sounds, sweat plays an important role. It’s like the coolant in your car’s system – not the most presentable part of your S$125,000 sedan but without it, you may not even be able to start the engine. Similarly, if you don’t sweat and let evaporation keep your body’s core temperature within its happy zone, you won’t be able to drive your body beyond a heat-induced coma.
But I do wonder: Just how much sweat does the average person produce? Why do some people sweat more than others? What’s in this bodily fluid that creates that unpleasant, sticky sensation on skin? Can you really sweat off toxins in your body? And with this weather, can you over-shower?
So, yes, we’re going to work up a sweat and ask the experts to address some questions and commonly held notions below:
JUST HOW MUCH SWEAT DO I PRODUCE A DAY?
It depends on your level of activity and the environment you’re in. Typically, a healthy, average-sized person produces 500ml of sweat every hour when performing a low-intensity activity (such as yoga or walking), said Dr Kok Wai Leong, a senior consultant and dermatologist at StarMed Specialist Centre. This rate can double to around 1 litre per hour with high-intensity exercise (any activity where you can’t say more than a few words without gasping for breath).
“In athletes and heavier individuals, the sweat rate can reach 2 litres per hour. In a day, the total sweat output can be as high as 10 litres, especially in hot and humid conditions,” said Dr Kok.
WHY DO I SWEAT MORE THAN MY FRIENDS?
There is a number of factors, said Dr Wang Ding Yuan, a consultant with National Skin Centre. In general, individuals with a large body mass, better physical fitness and better acclimated to hot weather tend to sweat more. Age is another reason; for example, older individuals tend to sweat less than younger people.
“Beyond that, there can be pathologic reasons why one sweats abnormally less or more than others,” said Dr Wang. “These can include the use of certain medications, neurological diseases, alcoholism, other systemic disorders (thyroid problems, heart failure or lymphoma) and rare genetic disorders.” And sometimes, there is simply no reason for the excessive sweat, he added.
CAN I SWEAT OFF TOXINS?
Let’s clear this up: Sweating’s primary purpose is to cool you down, not to help you detox. While small amounts of metabolic waste such as urea and ammonia are excreted through sweating, you lose more waste through your urine than sweat.
For instance, a drop of sweat is about 99 per cent water with the remaining 1 per cent containing traces of urea, ammonia and other substances. Urine, on the other hand, consists of 95 per cent water, 2.5 per cent urea and 2.5 per cent other waste products.
Many people have this misconception perhaps because they regard sweat as “an excretable bodily fluid”, much like urine, said Dr Wang. “The popularity of saunas and their supposed ‘sweat it out’ benefits, and the common belief of sweating as a means to overcome hangovers are probably symptoms of such a notion.”
Moreover, toxins are usually removed by the kidneys and liver – not your sweat glands, said Dr Kok.
I DON’T USE ANY UNDERARM PRODUCTS. BUT WHY IS THERE WHITE STUFF LEFT ON THE ARMHOLES OF MY CLOTHES?
You’re sweating the small stuff quite literally. That’s because each bead of perspiration contains trace amounts of minerals that dry into the white residue you see on clothes. These minerals include potassium, calcium and magnesium, said Dr Wang, who estimated that their quantities can range from 2 to 8 mmol/L, 0.2 to 2 mmol/L, and 0.02 to 0.4 mmol/L respectively.
As for why your sweat tastes salty, that’s because sodium chloride and water are the key components. “Some studies show sodium chloride at a concentration of 10 to 90 mmol/L”, said Dr Wang.
Sometimes, yellow stains can form on clothes but it’s not entirely owing to sweat alone. Rather, it’s your sweat’s interaction with the chemicals in anti-perspirants or the presence of micro-organisms that cause the fabric to turn yellow, said Dr Kok.
The discolouration can also be caused by a rare condition called chromhidrosis, a disorder that causes the sweat glands to produce a pigment compound, he said.
WHY DOES SWEAT FEEL STICKY AFTER IT HAS DRIED?
Other than the water, trace minerals and waste products that are inherently in sweat, this bodily fluid will also “mix with lipids or oils present on the surface of skin”, said Dr Wang. “After the water component of sweat has evaporated, the other constituents left behind on the skin surface is probably what imparts the sticky feeling.”
Clogged pores and acne can result as well at times, said Dr Kok, when sweat “mixes with dead skin cells and clogs the pores, making skin oily, sticky and prone to acne and dark spots”.
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I’VE BEEN WEARING MOISTURE-WICKING SPORTSWEAR EVEN WHEN I’M NOT WORKING OUT. CAN THERE BE POTENTIAL SKIN PROBLEMS?
In general, it shouldn’t be a problem lounging in your favourite pair of leggings, sports bra or quick-drying sports tee post-workout – although “loose clothing and breathable fabrics are preferred over tight clothing or leggings in warm weather to prevent heat rash”, said Dr Kok.
“In extremely humid conditions, sweat evaporation rates are lower, leading to the accumulation of sweat on the skin. Therefore, you would want to change out of these clothing into loose, clean clothes once you have completed your workout.”
Moreover, Dr Kok advises caution if you have eczema or contact allergies as moisture-wicking materials may contain triggering compounds such as phthalates. “Some fabrics can also feel rough and can irritate the skin and lead to rashes,” he said.
I’VE BEEN TAKING MORE SHOWERS TO COOL OFF AND WASH OFF THE STICKY FEELING. IS IT OKAY TO JUMP INTO THE SHOWER WHILE STILL SWEATY?
It’s not a bad idea actually, according to the experts. Dr Kok said that doing so would “allow skin to cool down to prevent heat rashes”.
Dr Wang isn’t aware of any ill effects of showering whilst still sweaty. “I don’t necessarily advise against it,” he said, adding to use a gentle, soap-free cleanser, keep your showers up to twice a day and 10 to 15 minutes each time, and use lukewarm instead of hot water.
In fact, it is recommended to take a shower as soon as you practically can after a sweaty activity “because the salts left behind can irritate skin”, said Dr Kok. If you can’t, dry off with a clean towel, so that sweat does not accumulate in skin folds, he said.
As for the fear of developing white spots on skin, showering while sweaty isn’t the cause. “White spots are typically caused by an overgrowth of a type of yeast on the skin, leading to a superficial fungal skin infection termed tinea versicolor,” said Dr Kok. “It is important to understand that fungal infections do not happen because of this practice.”
