As heard on your information update with Kristine Bellino this morning, according to Runners World, a man in Baltimore, Keith Levasseur is trying to get his name in the Guinness Book of World Records for running the Baltimore Marathon in 2 hours and 46 minutes, which is a good time, but it's because he ran it in flip flops. That sounds exhausting to me but still,  what a feat! Get it...feat?,
Anyway, Keith says,

"I knew it was all about maintaining a very efficient and balanced stride. There were times when my feet and ankles would get tired from maintaining a more rigid stride than I might otherwise have and I would start landing more on the outside of the my foot and cause my heel to slip off the sandal. It only happened a few times and when it did, it would refocus my concentration on my stride and posture."

(Runner's World)