This actually makes me happy. I'm glad when distance runners have problems like this. But this is charming: "To keep my rear alive, I must be vigilant about continuing to strengthen my lower abdominal and gluteal muscles. Last week, I slacked off and the pain came creeping back. Is it annoying to have to focus so much on these muscles to run? Absolutely. But if it’ll revive my butt, it’s worth every leg lift and crunch."