Christina posted a link to Why Joggers Labor and Olympians Fly, a good NY Times article about the physiology of running and why some people will just always be faster than others.
When I run, I have a bad habit of turning out my right foot. I first noticed it when I saw video of my crossing the finish line at the end of a 10K, but others who run with me have confirmed that the turnout is always there (and seems more pronounced at the end of a run when I’m tired). It’s only my right foot, which I kick back and out as I push off that foot. I can’t feel that I’m doing it, and thus far have been unable to correct it even though I know it makes me a less efficient runner than I could be otherwise. Though I will never be anything close to an elite runner like those mentioned in the article, I feel like I could improve over where I am now.
Next time I run I may do it on a track, so I can concentrate on putting one foot in front of the other like mentioned in the article. I don’t think it will correct the problem entirely, since it’s less to do with placing my feet in a straight line and more to do with the direction my leg kick goes in, but we’ll see.