Training with Marit Bjoergen and the Norwegian women’s cross-country team might be an intimidating prospect even for some of North America’s elite men. But not for Kikkan Randall. In the middle of a two-week visit to Norway this month, Randall took up an offer to go head-to-head with the country’s women’s squad in a double-pole interval workout. And while the pace was high—“pretty much all out”—Randall wasn’t blown away. “It was pretty cool just to...