Exercise-induced purpura: our advice to prevent it

What is exercise-induced purpura?

Sometimes, after a hike, some walkers get red patches on the feet, ankles and/or calves.

Initially, it is often assumed to be caused by an allergic reaction (to the socks or shoes worn), but in the majority of the cases studied*, it turns out that we are in fact dealing with exercise-induced purpura.

What is exercise-induced purpura?

The condition has only recently been recognised, while it is still largely unknown to the general public. Moreover, it is still not uncommon for doctors, who do not specialise in dermatology, to be ill-informed on the subject. Exercise-induced purpura is also known as exercise-induced vasculitis, marathon runner's vasculitis or golfer's rash (especially in Australia) for reasons you will discover...

It is characterised by the appearance of skin lesions similar to those seen after strenuous exercise (such as an ultra marathon). Symptoms vary with subjects sometimes complaining of pain or a burning sensation.

When does it occur?

Multiple factors can contribute to the emergence of this condition:

- a long walk particularly in the mountains or on rough terrain;

- a rather high outdoor temperature;

- we also note that it is more prevalent in women

Indeed, prolonged exercise involves significant energy expenditure, elevated muscle temperature (up to 41°C), vasodilation, a build-up of lactic acid, increased blood viscosity, inflammation, and muscle and skin lesions. These factors can result in a microcirculatory deficiency.

It can also suddenly occur in hikers with no prior medical history. Once you've suffered one episode, you are more likely to experience further relapses.

Can it be avoided?

There is no known treatment. Depending on the individual patient, treatment may include wearing compression stockings, taking vasoconstrictor medication or the administration of corticosteroids to help blood flow. We recommend consulting a dermatologist in order to find the most suitable treatment.

Good to know

Purpura can sometimes be confused with erythema. This common skin inflammation also causes rashes.

To tell the difference, you can carry out the following test: press on the lesion using a glass (spectacle lens, magnifying glass, transparent glass cup etc.). If the rash disappears, it is probably erythema (confirm with your doctor) and not purpura. 

Article drafted in consultation with Dr A. A. Ramelet, a dermatologist in Lausanne, who conducted studies on the subject and has written the following medical publications in particular.  

* Every summer, our product design teams get a number of notifications from customers who experience red patches on their skin following a hike. In this case, the socks used are sent away to undergo toxicological tests to assess whether they could be the cause of an allergic reaction. To date, the returned toxicological reports have always produced negative results, leading us to conclude that it is caused by exercise-induced purpura.

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