You can be an effective athlete with internal tibial torsion and tibial varum.
The video of world champ Mirinda Carfrae shows it beautifully on the right side during loading. The question is always, "how durable is your given anatomy ?".
How durable is your compensation ? And is there a cost when your endurance runs outor when the load gets too high ? Those are the big questions you have to ask.
In this video, stop the play at 34-37 seconds, keep playing that loop over and over again until you can clearly lock this in your head -- internal tibial torsion and tibial varum. See how far laterally she appears in initial weight bearing ? See the appearance of her apparent "in-toe"? You cannot correct this. You would be a fool to tell them to toe out more -- this would take her knee outside the sagittal plane. You leave this one alone. You make your athlete durable, giving them frontal plane and rotational-axial plane work to control those torsional forces during loading and unloading. The difference been you and her, is she has done this loading a trillion times, safely and built durability on the entire chain from foot to spine so the tissues can tolerate it. The question is, will there be a limit for her ? Will there be a point where the bone and soft tissues say they have had enough ? This is the golden question.
Some folks with this can be assisted by more step width separation, getting away from a Cross Over gait but Mirinda has a beautiful running form. However, in this particular video so does show some cross over gait, very narrow foot separation, and this magnified what you are seeing during her foot strike. In many other videos she does not cross over if you have studied her running form elsewhere.
As she says in her video, being a world champ is all about the details, details like we pointed out here today.
Know your anatomical variances. Know how they play out, and how they fail.
Shawn and Ivo, the gait guys