At 40 years old, he became the oldest snowboarder to win an Olympic medal. Now 43 years old, Nick Baumgartner says he feels faster than ever as he tries to qualify for his fifth Olympic games.

As recently as 2018, the U.S. was looking for its first Olympic medal in cross-country skiing since Bill Koch won the silver in the 30-kilometer race in 1976. That was the lone American cross ...