Well, I note that there are no genuine athletes on zero-carb(Charles is not viewed as a serious athlete by the genuine RVAF athletes I've come across). The issue re longer recovery-time while on zero-carb has been admitted by Charles, and there is some (admittedly primarily anecdotal) reports re zero carb being fine for aerobic activity but not anaerobic activity.
I suppose the real test would be to find any Inuit Olympic runners(on traditional ZC diet) and the like.
Inuit had a life that was physically demanding. Fishing, hunting, etc. in the Artic required a very good physical condition and recovery.
Same thing for Indians from the north. They were perfectly adapted to a zerocarb diet.
Today, there are so few people on zero-carb that I am not surprised that there are no genuine athletes among them!