Arnold attended the children's and youth sports school in Klingenthal. On the international stage, he made his first appearance at the Nordic Junior World Ski Championships in 1987 in Asiago, Italy , when he won silver in the individual competition on the normal hill after winning gold in the team competition two days earlier. In the same month Arnold started at the Nordic World Ski Championships in Oberstdorf, where he achieved 6th place in individual and 5th place in team jumping from the large hill.
At the 6th Summer Water Grand Prix 2012 in the Klingenthal outdoor pool, the unofficial world championships in water ski jumping, Arnold took third place.