The other perspective that makes this angle of her body plausible is if she where jumping/about to leap off a cliff or some high point.
Since she has no concern for landing her back leg this solution above is the only answer. There is no physical way the back leg could be brought forward to continue the run. Even if somehow it was able to get forward the 2 in heel of the boot would hit the ground twist her ankle/leg/knee into a pretzeel.
Escher Girls has picked up the image from the home page. If you're wondering what that means:
This is a blog to archive and showcase the prevalence of certain ways women are depicted in illustrated pop media, specifically how women are posed, drawn, distorted, and sexualized out of context, often in ridiculous, impossible or disturbing ways that sacrifice storytelling.
Cryptic, take note, this is not an "OMG a girl/sexuality/boobs being used to sell something" moment. It is the absurdity of the image itself which is meme-worthy. Walk it back before it spreads and the first thing the general population associates with STO is T'boobs and her memes.