What moves a woman to get on a dog sled and set out on a three-week ride over two mountain ranges and through Alaskan blizzards with a crowd of fierce competitors at her heels? A bout of cabin fever with a set of 2-year-old triplets? A determination to get ready for "the lightweight, more revealing clothes of summer" that the flab-reduction people are already warning us about? Or maybe just a yen to travel, combined with a fear of flying or a lifelong aversion to automobiles.

Libby Riddles, a fragile-looking, 28-year-old Alaskan, didn't need any of these excuses. She simply wanted to be the first woman to win the grueling, 1,135 mile Iditarod Trail Dog Sled Race from Anchorage to Nome -- and she was. The race was arduous enough, but the packing may have been worse. Imagine taking along 13 dogs, a three-week supply of food for yourself and them, a sleeping bag, a pup tent, tools for dealing with frozen terrain and, according to a story in The New York Times, eight booties for each dog to protect its paws on icy trails. Anyone who's left for an afternoon at grandma's worrying about the baby food, the apple juice, the car seat, the disposable diapers, the folding stroller and the teddy bear can appreciate the challenge.

Sixty-one competitors, male and female, started the race, and 49 finished. One woman, who had on two earlier occasions finished second, had to drop out because a moose killed two of her dogs. Miss Riddles pulled ahead when she set out alone in a blizzard that had stalled the others. "I kept on telling myself how foolish I was for doing this, because the weather was just miserable," she said later. "But I figured if it does pan out, it might help me win the race. So I'm going to try it even if it's crazy."

Ever since Billie Jean Kig beat Bobby Riggs, female athletes have been surprising us -- correction: some of us -- with one unlikely triumph after another. The Olympic marathon last summer was the most recent heart-warmer. Somehow, we didn't expect the next victory to come in dog sledding, but we're delighted that it did. Here's to all the mushers who made it -- most of all to Libby Riddles, who broke a barrier with a sled, a pack of dogs and a full measure of guts.