I have always read that it's best to make yourself look big and wave your arms and yell a lot, but NOT to go faster! Triggers a cat-prey response. I don't know how true this is, but I think I read it on an REI "bears and cougars" website post. Given what we know about cats, the loud scary noise part makes sense, as does the don't-inspire-a-chase part. However, that obviously has limited value if one sees you going fast, I suppose.