Maybe she should try not to run so fast on that, or what do you think igzigpuff?
Swede, don't think it would matter what speed she's going...
I notice the leg will hitch out whether she is wearing running shoes or heels (happens to the guys too).
My theory is that Sims have one leg longer that the other so it kinda bows out now and again.
Poor Dears!
I'm sure EA is aware of the issue...the folks on the official forum are not shy about voicing their complaints.