[1] He represented his native country at the 1936 Summer Olympics in Berlin, where he won the gold medal in the men's 1000 meter match sprint event.

At the World Championships in Brussels, he also won the title in the final against Dutch cyclist Arie van Vliet 2-1.

During the first race of the 1936 Olympic final, Merkens clearly interfered with Arie van Vliet, but no foul was called by the officials.

He was struck between the heart and lungs by a shell splinter, and died in a hospital in Wildbad after becoming ill with meningitis.

[4] In the Munich Olympiapark, the road between the main stadium and the velodrome is called Toni-Merkens-Weg (Toni Merkens Way).