Coached by Yves Kieffer at Pôle France INSEP in Paris, she was the French junior national champion in 2002.

At the 2004 Olympics in Athens, Le Pennec placed sixth with the French team and 14th in the all-around final.

However, she shone in the uneven bars event final, where her challenging routine helped her win a gold medal over a tough field with numerous Olympic and world champions, including Svetlana Khorkina (who took an infamous fall from the apparatus, which she traditionally dominated) and 2002 World Champion Courtney Kupets.

She also qualified to the all-around finals in first place, but lost any chance for a medal when she fell during her balance beam routine.

In it, she completed a Def (a Gienger release move with a full twist), an element classified at the top difficulty level, Super-E, in the 2005 Code of Points.