Długopolski started playing at the age of eight in 1988 and made his international debut at the age of sixteen in 1997, when he was used on the normal hill at the Nordic World Ski Championships in Trondheim , where he placed 44th. As early as November of the same year, the association used him for the first time in the Ski Jumping World Cup , where he steadily improved and in his fourth competition in Courchevel achieved his first World Cup points as 28th. Thanks to these good results, the Pole was invited to the 1998 Winter Olympics in Nagano - as the youngest athlete in his country - but with 45 points he only managed the last place of all jumpers. Nevertheless, he received further chances in the World Cup at the end of the season, but he remained without points. In the summer of 1998, the 18-year-old managed to win the Polish summer championship. On the other hand, he remained without points in the winter of 1998/99, but achieved two top ten results with the team at the Summer Grand Prix .
Długopolski took a longer break from competition, which lasted until December 2001. Then he returned initially with three competitions in the Continental Cup and although he remained without points there, he made his comeback in the top series of competitions at the end of January 2002. With the team he placed in the top ten for the first time in Sapporo , but only eleven nations were at the start. In other Continental Cup competitions he achieved a 21st place as the best result, which he improved when he was fifteenth in the following winter . Nevertheless, he mostly remained without a top 30 result in this class, so that he hardly recommended himself for the World Cup, where he only started again in January 2004 after finishing eleventh in the Planica Continental Cup. Over the course of 2004, the Pole convinced several times in the COC and was thus nominated for the first competition of the Four Hills Tournament 2004/05 in Oberstdorf . There, as 28th, he collected points for the overall World Cup for the second time, but he did not start in the other competitions and was only 53rd overall. Instead, he concentrated on the Winter Universiade 2005 in Innsbruck , where he achieved a good eighth place twice in individual and won the silver medal with the team. After that he did not reach any more points, but he achieved his best result there as 85th in the overall World Cup.
Summer 2005 was quite successful for Długopolski, in Hinterzarten he was sixth at the Summer Grand Prix both on the normal hill and in the team. With these successes he was nominated for the last time for the World Cup in January 2006, but again missed the points. For this he started again successfully in the Continental Cup 2005/06 by finishing second in the Villach jumping together with two tied athletes . With a total of 145 points, he placed 41st in the overall ranking. In January 2007, the Polish team did not defend the silver medal at the Universiade, but at least achieved fourth place. Throughout 2007 he continued to take part in COC competitions, but did not make it into the top ten. In August 2007 Długopolski declared his career end in active sport, but took part in an international summer competition in Frenštát pod Radhoštěm in August 2008 , which was organized outside the FIS and in which he was sixth. In addition, he only started in February 2009 for the last time at Polish championships. Since the end of his sporting career, he has held various coaching positions in the Polish national ski jumping team. Today he lives in Witów .