I'm reading Slow Burn by Stu Mittleman. Stu as a record holder for 6-day races. Yes, that means he runs non-stop for six days. He trains on a hi-fat, hi-protein diet. The book stresses running with a heart rate monitor. The goal is to never run so fast that the heart rate becomes elevated. When that happens, the body is using glycogen (stored carbs). It's been my problem for a long time: I try to run fast and always fail. The lower amount of carbs in the muscles of low-carb eaters means once you use up the carbs, there's nothing left to run on.

By following the book's recomendation, I am able to run without crashing. Over time, I should get faster while staying away from carbs. The process of turning into a fat-burning runner can takes several weeks. So far I've been able to run an hour a day without problems. In the past I've done 50-mile races on a low carb diet but typically I eat carbs while running. According to Mittleman, that shuts down the fat-burning system. I have races planned this Spring and Summer.