Un souffle pour la muco is a solidarity running event in Belle-Isle-Terre, Brittany, focused on raising funds for cystic fibrosis research. Held in April, it offers participants a range of distances, from a short 750 m to long routes of 65 km and 130 km, with intermediate options including 9 km, 20 km, 25 km, 30 km, 40 km, and 50 km. The listed entry fees for many races are modest, around 5 to 6 euros, aligning with the event's charitable focus.
The event evolved from the former rando muco de Belle-Isle-Terre, a regional gathering that had ceased before a group of friends revived it as Un souffle pour la muco. The cause remains central: cystic fibrosis is a genetic condition impacting breathing and digestion, and the event directs its efforts toward research funding. Featuring short distances, standard running courses, and ultra-distance options within the same program, it attracts families, casual walkers or runners, and those seeking a more extensive challenge.