How to cleanse your skin after exercise?

Engaging in sports can be a way to tone one's body. However, after a session of physical exercise, changes can be observed on our skin. It is due to these changes that post-exercise cleansing can prove to be fundamental.

Reason No. 1: The sweat produced during exercise can be odorous.

Indeed, during exercise, our sweat rate can increase compared to when at rest. In a study led by Lindsay R. KALAN and her team, researchers found that certain microorganisms showed particular preferences for sweat: this is the case for the commensal skin bacterium Staphylococcus epidermidis, typical of the skin flora of a healthy microbiota. However, in another study led by Niranjan NAGARAJAN, the results showed that different bacteria, including Staphylococcus epidermidis, could produce unpleasant odours.

The analysis of metabolic pathways has highlighted a production of isovaleric and acetic acid, responsible for a sour smell, by the enriched enzymes of S. epidermidis and a production of sulphur by the species of Staphylococcus, by breaking down certain constituents of sweat such as amino acids and fatty acids. Thus, washing the skin after sport will help to eliminate sweat and the characteristic odour with it.

Reason No. 2: Sweat can cause itching in some individuals.

Sweat can sometimes cause itching, particularly in individuals suffering from atopic dermatitis. It is hypothesised that a component of sweat that induces itching is highly concentrated in the sweat of those with atopic dermatitis. Therefore, the properties of sweat have been compared between subjects with atopic dermatitis and healthy subjects after perspiring in a sauna.

In the sweat of individuals with atopic dermatitis, the concentration of LL-37, an antimicrobial peptide, varied from one person to another. As LL-37 is recognised as being cytotoxic, it can be hypothesised that sweat containing high concentrations of LL-37 might promote inflammation and itching in individuals suffering from eczema.

Furthermore, sweat retention due to the occlusion of sweat pores has been reported in atopic dermatitis. The occlusion of sweat pores is supposedly due to biofilms of Staphylococcus epidermidis. Skin dryness and the increase in skin temperature due to sweat retention may partly contribute to the worsening of itchiness in atopic dermatitis. However, the scientific evidence for this latter hypothesis is still weak.

Furthermore, the epidermis has para-cellular tight junctions that act as a barrier to regulate skin permeability. A decrease in their expression results in water leakage from the body, leading to skin dryness, the penetration of pathogenic agents, and skin inflammation.

Studies have shown that dermcidin, an antimicrobial peptide found exclusively in sweat, is located not only within the sweat glands but also in the outer tissues in atopic dermatitis lesions, suggesting that sweat could infiltrate into the tissues.

Sweat contains proteases, histamine, salt, LL-37, and antigens. If it infiltrates the tissues, it can then cause tingling or itching sensations.

Reason No. 3: The sweat produced by exertion is uncomfortable.

Finally, sweat is simply unpleasant on the skin, it provides a sensation of discomfort. A sticky feeling to the touch, a wet appearance of the skin, a greasy effect on the hair... washing can therefore help to get rid of this impression of being "dirty".