For Kikkan Randall, a cross-country skiing world champion, working out in the off-season is about far more than sliding across the snow, The Wall Street Journal reported.

Randall spends spring and summer trying to build the explosive strength her grueling event requires. "I take a couple of weeks off and go to Hawaii, and do some biking while I'm there," she says. "But by May 1, I start training."

Randall, the world sprint champion for the 2011-12 season, is a major star in Northern Europe, where cross-country skiing is one of the most popular sports. In the U.S., it's something of an afterthought, even back home in Alaska, where she spends most of her off-season.

Her regimen is a brutal, six- (sometimes seven) day-a-week mix of roller skiing, biking, running and strength training. Pull-ups are a fairly unpleasant experience for most humans, but the ones Randall does resemble a form of medieval torture. She straps on a belt with a chain dangling from it and attaches a 60-pound weight to it. Or she'll pull herself up with such power that she is able to clap her hands above the bar and then grab it to slowly lower herself. Eight is her record.

"There's nothing that makes you feel more hard core than strapping on a belt and attaching a big weight to it," she said.

Randall does two workouts each day. She trains with a private cross-country skiing club at Alaska Pacific University. She meets the team at 8:30 each morning for what is usually a 2½-hour workout on roller skis. Once a week, the team has a session that lasts as long as four hours and can include runs of 12 to 15 miles on mountainous terrain.

During the regular session, Ms. Randall and her teammates spend the morning skiing intervals up and down the area's hills. They will often cover more than 25 miles in a morning with ease, though the distance varies depending on whether the team is working on endurance or speed.

Speed work requires interval training, which can be multiple one-minute bursts of sprinting with little rest in between.

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