This from the Journal of nutrition and Metabolism:
Great read and it makes the point that after fat adaptation strength and long endurance efforts are not affected on ketogenic diets, however anaerobic efforts that would typically put one in the glycolytic pathway are greatly compromised. it is interesting to note however that maximum aerobic capacity is neither enhanced nor decreased in a ketogenic diet.
Now this from the Journal of Applied Physiology:
The author makes the point that although fat is the primary fuel source for long slow events, the realities of racing dictate a need for glycogen for final kicks and things like that.
I have a few thoughts on this:
1-The more your sports or activities hang in the glycolytic pathway the more carbs you will need. One may be able to force a bit of fat adaptation in someone like a wrestler...more of their recovery after training may be fed from fat breakdown vs carbs, however if this person runs out of glycogen they are dead on the mat.
2-We can manufacture glucose from 3 sources. Gluconeogenesis from amino acids, lactate in the Cori cycle and glycerol in TAG/fat metabolism. Although the body can and does run quite well on ketones it would certainly be of survival benefit to have glycogen for brief, intense activities. Another way of putting it: if nature could have figured out another way to bridge the gap between ATP/CP and aerobic metabolism, it would have. Fro activities that are both intense and moderate in duration, carbs are essential if performance is the primary concern.
3-Ketosis, whether a consequence of strictly a low carb, higher fat diet or as a consequence of intermittent fasting, appears to confer a wide range of benefits.
4-This the interplay of performance, health and longevity IMO. What one do you want to emphasize? A nice way to balance this is intermittent fasting, likely with a CLC plan something like post WO carb feedings.