Word on the street is that 5K times are limited by VO2max; Half-marathon times by lactate threshold; and Marathons by glycogen storage. How do these factors affect us low-carbers? I am, specifically, a high-fat, meat & egg low-carber. Will I need to modify that diet in order to run long distances?
One of the things I've seen about fat metabolism is that it requires more oxygen to burn fat than it does to burn carbs. But I've only seen that claim; not the evidence behind it. Is it (practically) impossible to achieve world record times at 5K races as a low-carber because of that?
To what extent is lactate reduced by burning fat instead of carbs? This is one place where a low-carber might benefit. But I have no idea.
Glycogen storage is, of course, not an issue at all.
Unless a long-distance runner needs to burn carbs when running. I've seen many runners mention that they eat a lot of carbs before running, including carbo-loading before long races. They're only eating a low-carb diet whenever they're not running -- and depending on how often they run, that might mean low-carb only five days a week. Or four. Which isn't really low-carb, to me.
I've also seen many runners mention that they do just fine running long races.
An unanswered question among all this is how competetive the low-carbers are. If one maintains a strict low-carb diet 24/7, how competetively can you run?