I wonder if anybody on Ketosis has ever done an endurance event and not ended up feeling absolutely miserable/exhausted. I was on a fairly low carb regime (< 15 grams/day) for about 6 weeks, and something as simple as climbing fifty stories would always end up with me breathing heavy, and sweating. A simple 500 gram carb-load the day before, and I could that same climb 4x over without being anywhere near as exhausted.

The research that I've read says that the ideal training regime is to work-out in a carb-exhausted state, so as to encourage your body to develop the low-carb metabolic pathway, but for actual endurance events, definitely carb load as your primary fuel.