What is the origin of foot perspiration?

Key points to remember.

The soles of the feet have one of the highest densities of sweat glands, with 600 to 700 glands per square centimetre.
Unlike the rest of the body, plantar sweating is activated by emotional and mental stimuli rather than by heat.
Wearing closed shoes and synthetic socks promotes maceration by preventing the natural evaporation of moisture.
Change your socks daily and alternate your pairs of shoes to help limit bacterial proliferation on the feet.
Baking soda is a highly effective natural remedy for neutralising odours.

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How can we explain why feet perspire?

The skin on our feet has a unique anatomical characteristic: it contains one of the highest densities of sweat glands in the human body.

600–700

eccrine sweat glands per square centimetre on the soles of the feet.

64

of sweat glands per square centimetre on the back.

However, unlike in the rest of the body where sweat is primarily used to cool the body in response to heat, sweating of the feet is governed by different biological mechanisms. Various scientific studies have in fact shown that perspiration of the palms and soles of the feet is relatively insensitive to changes in external temperature.

For example, we can consider a study that compared the activity of the nerves on the sole of the foot (tibial nerve) with those on the top of the foot (peroneal nerve). The results are unequivocal: during a mental arithmetic task, the nerve impulses directed towards the plantar arch increase dramatically, reaching 1,000% of their resting level, whereas the top of the foot shows only a 117% change. The study also highlights an important distinction regarding thermal regulation. Although an increase in ambient temperature to 30°C does stimulate the sweat glands, this response remains far lower than that triggered by mental exertion.

290%

of increased plantar nerve activity following thermal stimulation.

1,000%

an increase in nervous activity following intellectual effort.

The activation of the sweat glands in the feet is governed by a distinct nerve pathway, linked to the sympathetic nervous system and to our emotions. Thus, intense stress or strong mental stimulation can increase tenfold the nerve activity directed towards the soles of the feet. From an evolutionary perspective, this slight moisture is thought to improve grip and friction between the skin and the ground, thereby making it easier to brace oneself in situations of tension. This is why we often sweat more from our feet during intellectual effort or moments of nervousness than during simple exposure to the sun.

Besides stress, various internal and environmental factors can increase perspiration of the feet.

Heredity, excess weight or certain hormonal changes can naturally increase sweating. In everyday life, wearing closed shoes or socks made from synthetic materials also contributes to perspiration, as these materials prevent the evaporation of sweat, creating an enclosed environment in which moisture accumulates. While physical activity also stimulates the glands located on the top of the foot to regulate heat, it is indeed the combination of our emotions and our footwear habits that determines the intensity of plantar sweating.

How can foot perspiration be reduced?

Several everyday measures can help to limit plantar hyperhidrosis, that is, excessive sweating of the feet. The first step is based on rigorous hygiene of both the feet and textiles. For example, it is essential to change your socks every day. We also recommend favouring natural fibres, such as cotton, which facilitate the evacuation of moisture. Alternating shoes can also be an effective strategy. By allowing each pair to rest for at least 24 hours, the materials have time to dry completely, thereby breaking the cycle of maceration that leads to bacterial proliferation and unpleasant odours. Another good practice to prevent the maceration of micro-organisms is to ensure that, after washing your feet, you dry them thoroughly and meticulously, especially between the toes.

To neutralise unpleasant odours at their source, bicarbonate of soda can be a valuable ally. By slightly modifying the pH of the skin, it creates an environment that is unfavourable to the development of bacteria responsible for unpleasant odours. You can sprinkle it directly inside your shoes or use it in a foot bath. In this case, feel free to add a few drops of vinegar or lavender essential oil, active agents that possess purifying and soothing properties which greatly enhance the effectiveness of the treatment.