Altimiras appeared internationally for the first time at the European Youth Olympic Winter Festival 2013 in Brașov . There he finished 77th in the sprint, 69th place over 7.5 km classic and 62nd place over 10 km freestyle. At the Nordic Junior World Ski Championships in 2014 in Fiemme Valley , he achieved 85th place in the sprint, 78th place over 10 km classic and 71st place in skiathlon . In the following year he came in the Nordic Junior World Ski Championships 2015 in Almaty on the 12th place over 10 km freestyle and on the eighth place in the skiathlon. In February 2016, at the Nordic Junior World Ski Championships 2016 in Rasnov, he achieved 47th place over 10 km classic and 21st place over 15 km freestyle. At the beginning of the 2016/17 season, he started in Valdidentro in the Alpine Cup for the first time and finished fifth over 15 km classic. The next day he won his first Alpine Cup victory over 15 km freestyle. At the beginning of February 2017, he finished eighth in the skiathlon and fourth in the 15 km freestyle at the 2017 U23 World Championships in Soldier Hollow . At the season highlight, the Nordic World Ski Championships 2017 in Lahti , he finished 33rd in the skiathlon and 29th place over 15 km classic. At the end of the season he ran the second fastest time in the Alpine Cup on the final stage of the mini tour in Seefeld in Tyrol and achieved third place in the overall ranking of the Alpine Cup. In the 2017/18 season, he took third place in the skiathlon and second place in the 15 km freestyle at the Alpine Cup in Campra . At the U23 World Ski Championships in Goms in 2018 , he was fifth in the skiathlon and fourth over 15 km classic. In February 2018 he ran at the Winter Olympics in Pyeongchang to 46th place in the skiathlon, 34th place in the 50 km mass start race and 27th place over 15 km freestyle.
At the beginning of the 2018/19 season, Altimiras scored his first World Cup points in the Lillehammer Triple over 15 km freestyle, which he finished in 41st place, with 21st place. At the Tour de Ski 2018/19 he came 24th. With the tenth place in the final stage in Fiemme Valley, he achieved his first top ten placement in the World Cup. At the U23 World Ski Championships in Lahti in 2019 , he finished 13th in the 30 km mass start race and ninth place over 15 km freestyle. At the season highlight, the Nordic World Ski Championships 2019 in Seefeld in Tirol , he came in 29th place in the 50 km mass start race, 22nd place over 15 km classic and 21st place in the skiathlon . At the end of the season, he achieved 43rd place at the World Cup finals in Québec and finally reached 55th place in the overall World Cup. In the 2019/20 season he achieved 23rd place in the Tour de Ski 2019/20 and 25th place in the ski tour, 44th place in the overall World Cup.
Participation in World Championships and Olympic Winter Games
Olympic games
2018 Pyeongchang : 27th place, 15 km freestyle, 34th place 50 km classic mass start, 46th place 30 km skiathlon
Nordic World Ski Championships
2017 Lahti : 29th place 15 km classic, 33rd place 30 km skiathlon
2019 Seefeld in Tirol : 21st place 30 km skiathlon, 22nd place 15 km classic, 29th place 50 km freestyle mass start
Andorra
Valdidentro