A recurring problem among female runners
Running is the sport that causes the most friction-related injuries. The repetitive motion of running causes overheating, which, at high intensity or over long distances, can cause painful burns and sometimes even lifelong scarring.
During marathons, many women suffer from burning under the breasts, on the collarbones and armpits, areas particularly exposed to friction.
In trail running, the longer the distance, the more these irritations appear, with the added bonus of back burns due to the hydration pack, which accentuates the movements of the bra. 
18 months of development and 7 months of testing
Aware of these issues, HÄSTKO initiated a co-development process by selecting 42 women prone to severe irritation. Prior to testing, 12 prototypes were developed and tested internally by the HÄSTKO team as well as by professional athletes such as ultra trail runner Stéphanie Howe. These tests helped refine the design and identify the most effective materials.
Then, two versions were submitted to the 42 testers selected during the UTMB® week, in order to arrive at the final version of the product, judged ideal after 7 months of experiments in real conditions , including intensive training, marathons and ultra-trails.
The test results are edifying:
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- 100% of testers noticed a total reduction in friction .
- More than 90% noted better moisture wicking , thus preventing maceration and burns.
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A majority confirmed that the support was optimal, comfortable and without excessive compression.
A revolutionary bra
Following these tests, HÄSTKO finally unveiled the BRA N°42 during the Paris Marathon , a bra designed specifically to meet these challenges.
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- 100% seamless : no friction points, thanks to a fully welded and thermoformed assembly.
- Ultra-light and breathable material for rapid moisture wicking .
- Welded folded edges and laser-cut finishes for absolute comfort.
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Strategically placed mesh zones for optimal ventilation.
High-performance support
HÄSTKO uses individual breast encapsulation technology . A welded internal structure and external 3D printing envelop each thermoformed cup, ensuring a perfect fit without excessive compression . The result: complete freedom of movement and protection against chafing.
See you at the Run Experience Show at the 2025 Paris Marathon
Come and discover and test the BRA 42 in preview at the Paris Marathon 2025 Show, stand 41. And on April 16, 2025 at Au Vieux Campeur in Paris from 6 p.m. for an exceptional evening. A unique opportunity to try the bra that could well revolutionize your running practice !
👉 Discover our testers’ testimonials on Instagram:
