In her first year, she obtained ninth place in the 5 km freestyle, at the 1997 FIS Junior World Ski Championships in Canmore, Canada.

In 1999, she achieved a podium position at the FIS Junior World Ski Championships in Saalfelden, Austria with a 3rd place in the 5 km C, a race where athletes like Marit Bjørgen, Petra Majdič, and Aino-Kaisa Saarinen were also competing.

Longa also earned great results in the Continental Cup, including the win at the 5 km classical stage in Candanchu, Spain where she preceded Majdič|.

Longa ended the 2003 season in 51st position in the world cup overall standing achieving a 7th place in the 10 km classical mass start as top result.

In the summer of 2008 she also competed in roller skiing races to speed-up her recovery, obtaining a victory, two seconds and a fourth place.

A month after, she won two medals at the 2009 FIS Nordic World Ski Championship in Liberec with a silver in the 10 km C and bronze in the team sprint C event.

She ended the 2010 World Cup season in ninth position in the overall standings, with the major World Cup results of a third in Lahti in the 4 × 5 km relay, and a fourth place in the 10 km classical in Rukatunturi, Finland In January 2011 she obtained third place in the 2010-11 Tour de Ski, arriving third on the final climb finish in Val di Fiemme, following Justyna Kowalczyk and Therese Johaug.

On the last race, the 30 km, she obtained the eight position in a spectacular day, where Johaug offered an outstanding performance securing the gold medal ahead of Bjørgen and Kowalczyk.