[quote=@Satoshi Kyou]
true... but i am also putting in consideration a person's perception... i mean she runs a lot. if she didn't run a lot she would have tripped more easily but whatever.
[/quote]

Putting your foot in someone's way of stepping would make ANYONE trip at that speed. Balance isn't really a factor when it's actively disturbed.

If she was someone like Transformer, yeah, Ethel would have broken her foot trying that, but she's not. 

EDIT: Keep in mind, Ethel timed it exactly AS hayate ran through. So jumping over couldn't happen.