Heimdal, who starts for Dølaski, ran his first World Cup race in Lahti in March 2000 , which he finished in ninth place in the sprint. In the 2000/01 season he achieved after 84th place in Beitostølen over 15 km classic, in Oslo with second place in the sprint his only podium finish in the World Cup. In the following season he came in seventh place in the sprint in Stockholm again in the top ten and completed his sixth and last World Cup race in Oslo in March 2002, which he finished in 16th place in the sprint. He also takes part in ski marathon races. He won the Reistadløpet eight times (1994, 1996, 2000, 2002, 2003, 2005, 2006, 2008).