Nutr Metab (Lond). 2004 Aug 17;1(1):2.
Ketogenic diets and physical performance.
Phinney SD.
"Abstract
Impaired physical performance is a common but not obligate result of a low carbohydrate diet. Lessons from traditional Inuit culture indicate that time for adaptation, optimized sodium and potassium nutriture, and constraint of protein to 15-25 % of daily energy expenditure allow unimpaired endurance performance despite nutritional ketosis."
http://www.ncbi.nlm.nih.gov/pubmed/15507148