Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "
Endurance athletes prepare better for races with a low-carb diet
Endurance athletes who are preparing for competitions may achieve better results if they cut their carbohydrate consumption right down, and replace the carbs with unsaturated fatty acids. Polish sports scientists drew this conclusion after performing a study in which 8 experienced male mountain bikers followed a low-carb ketogenic diet for four weeks.
Endurance sports paradox
You'd expect that endurance athletes would be better off following a diet that provides most kcals in the form of fat – which would encourage their body to learn how to oxidise fats.
The researchers monitored the concentration of the enzymes LDH and CK in the athletes' blood. The higher the concentration, the more muscle damage there is. From their measurements the Poles could see that the low-carb diet reduced muscle damage incurred during exertion.
On the other hand the subjects' maximum workload had decreased – at least, after the low-carb diet the athletes generated fewer Watts. From this the Poles concluded that a ketogenic diet is probably ideal preparation for competition, but that just before and during races endurance athletes are probably better off eating carbohydrates.
"High volume training on a ketogenic diet increases fat metabolism during exercise, reduces body mass and fat content and decreases post exercise muscle damage. Low carbohydrate ketogenic diets decrease the ability to perform high intensity work, due to decreased glycogen muscle stores and the lower activity of glycolytic enzymes, which is evidenced by a lower maximal work load during the last 15 min of the high intensity stage of the exercise protocol."