To run like a girl

The other day, this phrase popped into my head. She's running like a girl. Then I shook my head. What was wrong with me?

But there wasn't anything else for me to say. "To run like a girl" was the phrase that directly captured what I was seeing, never mind that girls who run regularly usually don't run that way. Somehow, to run inefficiently, in that peculiar style with the forearms flailing out to the sides, the upper and lower body rotating sideways in opposition to each other, is to run like a girl.

If I just say her running form was bad, it could mean any number of things, but "to run like a girl" somehow captures that specific bad form. Which I, of course, last remember seeing done by a boy. Oh, to live in a language where the idioms are not gendered. What can I say that captures what I saw more specifically than She had poor form without reinforcing sexist beliefs?

And have we yet reached the point where little girls and little boys both participate equally in sports that require them to learn how to run?