After a long day at work, for some the height of luxury is a long, hot, and almost scalding shower.
A quarter of an hour, even half an hour is enough to evacuate bodily impurities and worries.
But hey, high temperature washing isn't just bad for energy use and the planet.
It is also for your body.
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Enemy of heavy legs
Human beings manage to maintain their body temperature around 37°C, thanks to brown fat, also called adipose tissue.
To diffuse this internal heat towards the skin and its extremities, the blood circulation comes into play. However, an increasingly hot jet of water leads to vasodilatation, ie an increase in the diameter of the blood vessels and blood flow.
And if the process is normal or even beneficial for oxygen exchanges, the decongestion of internal organs and muscle relaxation, it can aggravate the symptoms of people suffering from venous insufficiency, points out Sophie Blaise, professor of vascular medicine at the University Hospital of Grenoble. .
As a reminder...
Venous insufficiency does not only concern women and the elderly.
"It can occur from the age of 20, especially if there is a family history or other risk factors: venous malformation, obesity or even a sedentary lifestyle", underlines Professor Sophie Blaise.
According to the specialist, this condition is most often identified by swelling of the legs (calves, ankles or feet), associated with this famous feeling of heavy legs, or varicose veins, or dilatations of superficial veins on the leg.
“In case of venous insufficiency, the blood stagnates in the veins of the lower limbs.
Normally, the contraction of the muscles participates in bringing the blood back to the heart, but the heat of the shower associated with the almost immobile position that it implies, will reduce this pressure and thus further limit this venous return”, specifies Alain Géloën. , research director at the CNRS.
Dryness and dehydration
The skin is also impacted by excess heat.
“Beyond 39°C, the water will gradually melt the outer layer of the epidermis, the “hydrolipidic film”, whose role is to act as a barrier against external aggressions, reports Alain Géloën, director of research at the CNRS and also author of
Microbiota cutaneous
(1).
Without this film, the skin is then more easily dehydrated, which explains this feeling of tightness when leaving the shower.
"If the excess temperature is too frequent, it can weaken the epidermis and cause increased sensitivity, which can lead to atopic dermatitis, better known as eczema," says Alain Géloën.
Hence the importance of rehydrating the skin with emollient creams, once the body is dry.
Skin microbiota imbalance
In the care department, beware of cleansing products.
A high temperature, combined with cleansing gels rich in preservatives and potentially allergenic texturizing agents, will produce a detergent effect on the skin, which is harmful to our skin microbiota.
“If 5% of bacteria are harmful, the majority of them contributes on the contrary to defending the skin against infections, by occupying space in large numbers, explains the director of research at the CNRS, Alain Géloën.
However, the hot water will participate more in detaching them one by one.
The specialist also recalls that it is important that the body be accustomed from childhood to being in contact with bacteria, so that the immune system gets used to the “good ones”, and can prevent pathogens from settling. .
Far from the knob, closer to the smells?
"You can wash every day, reassures Alain Géloën, provided you do not rinse excessively, with temperate water, and with a neutral pH product or shower oil, without rubbing too much".
(1) Alain Géloën is co-author with Alexandra Raillan of
Cutaneous microbiota
, Ed.
First, 240 pages, €15.95.
