On December 29, 1983 Proswirnin made her debut in the Nordic Combined World Cup at the World Cup in Oberwiesenthal and took second place behind Andreas Langer from the GDR at his first start . In the same season he took part for the Soviet Union in the 1984 Olympic Games in Sarajevo and finished sixth in the only Nordic combined competition. He also took part in the Nordic World Ski Championships in 1984 , which were held because the team competition in the Nordic Combined was not an Olympic competition. In the team competition, Proswirnin won the bronze medal behind Norway and Finland together with Alexander Majorow and Ildar Garifullin . At the end of the 1983/84 season he finished fourth in the overall standings with the German Thomas Müller with 72 World Cup points.
In the following season he took part in the Nordic World Ski Championships in 1985 and finished 14th in the individual competition. In the team competition, he finished fourth with Allar Levandi and Alexander Majorow behind the teams from Germany, Norway and Finland.