Colchen first emerged as a high jumper in the mid-1940s and she ranked in the world's top twenty in 1944, clearing . She rose to the peak of the international scene with a gold medal win at the 1946 European Athletics Championships, holding off the Soviet all-round athlete Aleksandra Chudina with her winning height of . As of 2015, Colchen remains the only French woman to win a European high jump title (Jacques Madubost won the men's event in 1966). She followed this with a silver medal in the 4×100 metres relay, running alongside her compatriots Léa Caurla, Claire Brésolles and Monique Drilhon to finish behind a Fanny Blankers-Koen-led Dutch team.