I'm capmikee's wife and really struggling with the whole running/low carb thing. For me, the problem is not being able to run the distance, it's the performance issue. Running on low carb has always meant two things for me: low speed (and I'm slow enough as it is) and injuries. Whenever I have trained seriously, my times always drop like crazy if I eat carbs (unfortunately, I also gain weight).

I have seen the mitochondria issue mentioned in running books. Basically, I think it is the reasoning behind carbloading diets for marathoning. Nowadays, people carbload pretty much all the time, but orginally carb loading meant eat low carb while in training for two purposes - to fat-adapt by increasing mitochondria and to induce the muscles to go hyperactive on glycogen-loading when carbs are finally introduced just before a performance test (i.e. a race). All marathoners are well-served by becoming more fat adapted, because at some point the glycogen runs out in everyone.

I am at a crossroads, about to start marathon training. Wishing I could lose weight. Capmikee race a five mile race with me recently and was slower than I expected (still awesome since he's not really a runner)!- that was not a great confidence booster for low carb running.