Rosa was born in Troviscal, Oliveira do Bairro. She began her career as a cross country specialist. She won the 2000 World Student Cross Country Championships and established herself on the senior national scene as well, taking three straight short course titles from 2000 to 2003. She made her major international debut at the 2000 IAAF World Cross Country Championships in Vilamoura, running in the short race. She switched to the long race at the next edition and reached the top-fifteen runners. Over the following seasons, she made a number of other top-twenty finishes (including 11th in the long race and 16th in the short at the 2003 IAAF World Cross Country Championships). Her world cross career was highlighted by a team bronze medal at the 2005 edition, where she led the national team with a fifteenth-place finish. She also reached the top ten at the European Cross Country Championships in 2004 and 2006.