ergo-log.com

Definition: "An ergogenic aid is any substance or phenomenon that enhances performance "

about us

/

contact

/

16.02.2010


Low-carb diet gives endurance athletes more stamina

Endurance sports gurus are still singing the praises of extremely high carbohydrate eating patterns, but studies suggest that a low-carb diet may also be interesting for endurance athletes. If you put experienced cyclists and triathletes on a fat-rich diet for 6 days, their bodies become more economical with sugars, they burn more fat and their stamina increases slightly, even if they go back to a high-carb menu on the day of a race. Sports scientists at the RMIT University in Australia reported this a decade ago in the Journal of Applied Physiology.

Low-carb diet gives endurance athletes more stamina
The researchers gave 7 test subjects a standard diet on day 1, consisting of 58 percent carbohydrates, 27 percent fats and 15 percent protein. After that the subjects were put on a low-carb diet, where 69 percent of the energy came from fats, 16 percent from carbohydrates and 15 percent from proteins. On day 9 the subjects were given a high-carb diet, with 70 percent of the energy in the form of carbohydrates, 15 percent from fats and 15 percent from carbohydrates. [FAT-adapt]

On another occasion the test subjects were given a diet with a very high carbohydrate content from day 2. [HCHO]

On days 2, 5 and 8 the researchers got their subjects to cycle for 15 minutes at a reasonable speed at 65 percent of their VO2max while determining from which food types the athletes were getting their energy. This was done in the mornings, before the subjects had had breakfast. On day 9 the researchers did the same, but got the subjects to cycle for 4 hours at 65 percent of their VO2max.

When the test subjects had been on a low-carb diet for a week they burned more fats and less carbohydrates, as the figure below shows.


Low-carb diet gives endurance athletes more stamina


During the 4-hour bike ride, the low-carb diet raised the concentration of fatty acids and glycerol in the blood. This suggests that fat cells release their content more easily in the blood.


Low-carb diet gives endurance athletes more stamina


After the 4-hour bike ride the test subjects did another 1-hour ride. The graph below shows that the low-carb diet helped the subjects to cover a slightly greater distance.


Low-carb diet gives endurance athletes more stamina


However, the effect was not statistically significant. The authors therefore conclude that a low-carb diet is not of interest to endurance athletes. "A high-fat, low-carb diet, followed by 1 day of carb restoration, increased fat oxidation during prolonged exercise, yet, this study failed to detect a statistically significant benefit to performance", they write. We on the other hand, not hindered by a knowledge overload, draw the opposite conclusion.

The study was funded by Nestle, a producer of high-carb sports foods for endurance athletes.

Source:
J Appl Physiol. 2001 Jul;91(1):115-22.