From Washington Post:
Her mechanics, common among male swimmers but almost unheard of among women, is often described as a “gallop†or a “giddy-up†stroke, or is said to have a “hitch.†Ledecky has called it a “loping†stroke. Essentially, instead of a steady, metronomic beat — left, right, left, right — her stroke is syncopated: short left, long right, short left, long right. She breathes almost exclusively to the right side.
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Yuri Suguiyama, Ledecky’s coach from age 10 to 15, taught her that stroke in the spring of 2011 — about 15 months before she would win gold in London. To hear Ledecky tell the story, it was more or less accidental: She was doing a drill where she was asked to reduce her number of strokes per lap and had to lunge — or gallop — to reach the wall.
“She was swimming more like a classic female distance swimmer,†he recalled. “She would breathe to both sides. She had kind of a sporadic kick, or what we call a two-beat kick. And I don’t know — I just didn’t like the way she swam. . . . I think I was watching a Phelps race from 2007. His legs were moving the entire time. He had a nice little hitch, or a gallop, and I was like, man, Katie could swim that way. . . . It just takes advantage of the aggression and the kind of fury that she swims with.â€
If the best female swimmer in the world swims one way, it would make sense for others to try to copy her. But it isn’t that easy. The gallop stroke requires tons of core strength, the sort many male swimmers possess but few females do.
“We found that it’s a very hip-driven stroke, and I have really good rotation and rhythm with my hip rotation, and I get a lot of power out of my hips,†Ledecky said. “So that stroke kind of maximizes that.â€