The human Sweat – a short introduction
Sweating – also known as perspiration, transpiration or diaphoresis – is a natural and vitally important function to balance temperatures by evaporation (thermoregulation). The human perspiration is typically associated with physical activities, hot weather, humid air and with fever, too. Various other factors such as the menopause, puberty, nervousness and several diseases are also known to cause sweating.
While sweating, the body produces aqueous and salty fluids. This bodily sweat is secreted from over 3 million eccrine (also: merocrine) sweat glands which are spread all over the skin. By the way: the other known type of dermal glands, the apocrine sweat glands do not produce any sweat.
Excessive sweating – basic facts:
Increased sweat production is commonly an inherited condition. In other cases the onset is based on manifold changes in life, for example changes of the hormone level, changes of one’s personal diet, of the clothes or fabrics, emotional changes and so on.
Excessive sweating can affect those who suffer from it on a social, functional, and emotional level. Nevertheless, most people still think that even the worst sweating conditions are quite normal and natural. Outsiders would keep on quoting old fashioned insight and wisdom, like “Sweating is healthy!” or “It’s dangerous to stop your sweating because it’s essential!” They rather should become aware of the fact that heavy perspiration is never acceptable for the person concerned.
Why? See below.
Common complications of excessive sweating
Complications are rarely medically serious, they include significant psychological distress, as well as skin problems:
- Social and emotional strains
Excessive sweating causes serious mental problems. More than 35 % of people with sweat problems say their symptoms are intolerable or barely tolerable. They avoid social and professional opportunities because of embarrassment. Many report difficulties in their romantic lives because of excessive sweating.
- Maceration (fishy skin)
The softening and whitening of skin that is kept constantly wet. The mushy, peeling skin can lead to other skin conditions, which are usually mild but annoying.
- Tinea cruris (Jock itch)
An itching fungal infection in the folds of the groin. Heavy sweating around one’s private parts creates a continuous moist environment – the perfect climate for mycosis.
- Tinea pedis (Athlete’s foot)
Athlete’s foot is a fungal infection of the feet. The fungus thrives in moist conditions, mostly in between the toes or on the sole.
(c) scape | media
- Bromhidrosis (body odour)
Sweat itself does not smell bad. It’s the acids skin bacteria create when they decompose the salty fluid. The sweat in the underarm and genital areas is most prone to create body odour. Smelly feet are best known (or feared), too.
(c) sascha ballweg
- Warts and bacterial infections
Damp skin, permanently soaked from sweating can allow easier entry for bacteria and viruses that cause all kinds of skin infections and warts. A prominent wart is the Verruca plantaris, the plantar wart that grows vice versa – into the skin.
There is a only a thin line between increased sweating and Hyperhidrosis, the medical term for abnormal sweating. This clinical condition is descriped here.
Interesting sweating facts
Sweating in words and figures
- under normal conditions an average person sweats up to 6 liters per day
- a hard working adult can sweat up to 15 liters a day
- 250 ml of sweat (per day) come from the feet
- a bedding is soaked with 2 liters of sweat per year (night sweating)
- there are 2 – 4 million sweat glands distributed all over the human skin
- most sweat glands can be found on the feet, hands, forehead and groin
- the fewest can be found on tighs and upper arms
- maximum: there are over 250,000 sweat glands on the feet
- misconception: the axillary area does not contain many sweat glands
- underarm sweating is furthered by lacking air circulation
- men have more hair follicles, thereby more apocrine sweat glands
- women have more eccrine sweat glands than men, but:
- men typically have more active eccrine sweat glands
- men tend to sweat faster than women 1
- men have a higher sweat loss than women 1
- trained athletes sweat more and faster than unexercised persons
- fun fact: pigs do not sweat, they coat themselves in mud to stay cool
- fun fact: dogs and cats can sweat through the pads on their feet
- fun fact: a rabbit’s sweat glands are around its lips
- fun fact: kangaroos cool themselves by licking their fur
- fun fact: camels can sweat up 25 % of their body weight without dehydration
- a human can sweat away a maximum 12 % of body weight
- Hyperhidrosis sufferers sweat 3 times more than average persons
Eccrine sweat is made of …
- water (approx. 99 %)
- salt (NaCl) + electrolytes (potassium, calcium, magnesium)
- Vitamin C
- long chain fat molecules
- urinic traces (approx. 0.0013 %)
Perspiration is NOT used for detoxication!
A common misbelief and misinterpretation is that sweating is useful for the excretion of toxic agents and purification. Some miracle healers even claim people should never reduce their sweating with antiperspirants, otherwise their bodies would get ‘polluted’ from inside. However, this is not true. Toxic agents are solely filtered and excreted by the kidneys or the liver. Only in rare cases, when both organs are severely affected by illness, the body would use the skin to emit harmful substances (e.g. yellow jaundice). Scientists know that human sweat may contain minimal traces of urinic substances from time to time but the amount is very minuscule – it could never be used for an efficient excretion of bodily ‘waste products’.
Perspiration will NOT help burning fat or calories!
It is hard to believe that people still fall for this. Sweating has nothing to do with fat burning. Some tremendous workout at the gym has, though. Or endurance sports. And one’s personal diet, of course. But fat (or whatever) is not excreted by the sweat glands. Scientifical examinations of sweat have shown that sweat contains long-chained fat molecules. This fact might be the origin of the misbelief. However, sporty people who may sweat like a horse for several hours still lose their fatty tissue by muscular exercise, not by sweating. The loss of water, of course, would be gaugeable, too. Persons who tend to sweat excessively should always keep an eye on dehydration which can become a serious health issue while training. Therefore, the continuous substitution of fluid (water) and electrolytes is very important.
picture above | Save your money. Sauna sweat-suits like the silver overall shown above are noneffective. Burning fat and calories has nothing to do with sweating.
Correct measuring of sweat rates and body mass losses
Sweat losses and sweat rates can be measured using various sophisticated techniques in laboratories. In the field, the most practical way for athletes to monitor their sweat loss is to measure changes in body mass, with corrections made for fluid/food intake, as well as urine losses. In monitoring changes in body mass, athletes weigh themselves prior to training in minimal clothing. Immediately after training, they weigh themselves again in identical dry clothing on the same set of scales. The weight of any food/fluid consumed is then added to the calculation, before estimated urine losses are subtracted. This will provide estimate of sweat losses over the whole session. Dividing the total sweat loss by the duration of exercise will provide an estimation of the rate of sweat loss.
|pre-exercise weight||= 55 kg|
|post-exercise weight||= 53.5 kg|
|volume of fluid consumed during exercise||= 1 L = 1 kg 2|
|estimated urine losses||= 500 ml = 0.5 kg
|exercise duration (in hours)||= 2 h|
|fluid deficit||= 55 kg – 53.5 kg = 1.5 kg|
|total sweat loss||= 1.5 kg + 1 kg – 500ml = 2 kg|
|sweat rate (L/h)||= 2 kg/2 h = 1 L/h|
Five examples for athletic sweat rates: 3
- Running (1o km; Ø speed 13 km/h): females 1.5 L/h; males 1.8 L/h
- Marathon (42.2 km; Ø speed 11 km/h): females 0.7 L/h; males 1.6 L/h
- Cycling (40 km; Ø speed 30 km/h): females 0.75 L/h; males 1.14 L/h
- Baketball (competition): females 0.9 L/h; males 1.6 L/h
- Soccer (competition): females 0.8 L/h; males 1.2 L/h
The more sweat, the better the workout?
Nope. Sweating is pretty synonymous with working out, but it is not necessarily a measure of how effective your workout is. The only important indicator of efficiency is provided by measuring the heart rate and calories burned.