do men really sweat more than women?

Men are generally taller than women, but we do not define gender by height. Likewise ours latest research shows that we cannot define men and women by their tendency to sweat (although some parents and partners may suggest otherwise).

When we studied men and women exercising in warm and dry conditions, sex differences in responses to heat loss (skin blood flow and sweating) could almost entirely be explained by individual differences in body size and shape.

The results disprove the popular saying “men sweat and women glow.”

How objects and bodies lose heat

Heat loss from any object is dictated by its surface area to mass ratio, known as its “specific surface area.” Hot objects with a larger specific surface area cool faster than those with a smaller specific surface area. Doubling the radius (size) of a sphere increases its surface area fourfold but its mass eightfold: this is called “isometric growth.” Isometrically larger objects do not lose heat as easily.

Shape (morphology) also has a huge impact on heat loss, which is why a thin rectangular prism loses heat much faster than a sphere of the same composition and mass. In previous articlewe explained that the risk of heat loss through the head is no greater than through other parts of the body.

Unlike geometric objects, animals do not grow isometrically; we retain the recognizable shape, but our proportions change (this is called “allometric growth”). This is most noticeable in children, who have proportionally larger heads and shorter limbs than adults.

However, if you double your weight by building muscle and storing fat (without changing your height), it will not double your skin surface area. This change in weight increases the surface area only about 30%which translates into reduced specific surface area and lower heat loss through these physical mechanisms. The larger a person is, the smaller his surface area and the less effective these mechanisms become. This is where physiological mechanisms of heat loss, particularly sweating, come into play in preventing unwanted heat gain.

Sweating and evaporative cooling

Since man has evolved in the heat of Africawe have acquired the ability to transfer heat from deep within our bodies to the surface of our skin to be dissipated through blood flow in the skin. Similarly, we have acquired an evaporative cooling mechanism that can operate when the air is hotter than the skin: sweating. These physiological responses allow us to manage body heat and are activated when physical heat loss becomes insufficient.

To investigate the effects of body shape and gender on these two physiological responses related to body heat management, we studied men and women (60 university students) with widely varying but overlapping body sizes. The subjects had very similar exercise habits, endurance and body fat.

For each participant, we calculated a target exercise intensity related directly to skin surface area. This resulted in a comparable increase in body temperature for all participants and equivalent heat loss requirements. To the best of our knowledge, this was the first study to achieve such results in a morphologically diverse sample of men and women. Previous researchers appear to have failed to fully appreciate these important experimental design criteria, leading to experiments that perpetuated the myth that all men sweat more than women.

Our analyzes showed that differences in blood flow and skin sweating in men and women depend not on gender, but on body morphology.

By answering our questions, we showed that the song lyrics “Down” (Men at Work) require modification.

Do you come from the land below?

Where women shine and men plunder?

Although we do come from the land below, and although some men may unfortunately still plunder, women do not radiate. They sweat just like men and for the same reason: to lower their body temperature.

Three different types of sweat

To consider the relationship between sweat and body odor, we need to look a little broader.

The ubiquitous sweat glands that humans have for evaporative cooling are called “eccrine” glands. However, we all have two other types of glands in our skin: Apocrine and apoeccrine glands..

While eccrine glands are distributed throughout the body, apocrine and apoeccrine glands have a limited distribution and are located mainly in areas where longer – sometimes curlier – hair grows in adults (regardless of whether we remove it).

Apocrine glands are located next to hair follicles, where they secrete a milky, oily fluid. The apoeccrine glands, which appear to develop after puberty, appear to be the dominant gland in the armpits. They secrete a watery fluid similar to eccrine glands.

The odor that we sometimes smell around sweaty people or their clothes comes mainly from the secretion of the apocrine and apoeccrine glands. These secretions are initially odorless, but the action of bacteria on this fluid leads to smelly men and smelly women.