When a character from an anime (usually a ninja or something like that) runs with their arms pointed out behind them, seeming like they're limp and they're flowing with the wind.
Since doing this makes running even harder, it can be suspected that anime characters run like that because the animators are too lazy to animate their arms going back and forth, so they just point them backwards.
Matt: Hey look at Johnny! He's doing an anime dash! It looks cool!
Josh: Yeah, it won't look cool when he lands on his face. There's a reason why we move our arms when we run