Olympic sports sometimes get retired (see: polo, tug-of-war), but sometimes that fate befalls specific events. For example, between 1936 and 1956, the Olympics held 10 kilometer races. In canoes.

The two-man 10k was introduced in 1936, and the one-man was added in 1948. At least, with two men, you can chat during the 10 kilometers... With one? You just kneel and paddle, kneel and paddle. Leon Rotman of Romania, who won that last ever C-1 10k, did it in 56 minutes. An hour of kneel and paddle, kneel and paddle...

Rotman seemed to be superhuman: a day after he took down the 10k, he came back and won the 1k as well. When he returned for the next Olympics four years later, the longer race was retired, but he added another 1k medal, a silver, to his tally.

Now, even though the 10k is no longer in the Olympics, there are special world marathon canoeing championships. Some of those races are much longer than 10k, and some involve grueling affairs on back-to-back days.

Kneel and paddle, kneel and paddle...