He was a member of the Yugoslavian delegation at the 1928 Summer Olympics in Amsterdam; he won a bronze medal with the men's all-around team, together with Edvard Antosiewicz, Dragutin Ciotti, Stane Derganc, Anton Malej, Janez Porenta, Jože Primožič, and Leon Štukelj.

At the 1930 World Artistic Gymnastics Championships in Luxembourg, Gregorka was a member of the all-around team that won a bronze medal, together with Antosiewicz, Malej, Primožič, Štukelj, Rafael Ban, Peter Šumi, and Stane Žilič.

[3] At the 1938 World Artistic Gymnastics Championships in Prague, Gregorka was again a member of the bronze medal-winning team at the all-around team event, together with Primožič, Stjepan Boltižar, Miroslav Forte, Josip Kujundžić, Janez Pristov, Miloš Skrbinšek, and Josip Vadnav.

After winning a skiing competition in Krvavec, Gregorka received a medal carved out of a fresh potato.

He was the coach of Miroslav Cerar who won three Olympic medals, including two gold in pommel horse at the games in Tokyo and Mexico City.

[3] In addition, Gregorka was a sport referee and served as a member of organization committees for several competitions, including the 1970 World Artistic Gymnastics Championships that took place in Ljubljana.