Gabe Mirkin, M.D.
A study from The University of Bern in Switzerland
shows that a high carbohydrate, high-fat diet for three days
before competition can help athletes store more fat in their
muscles and use much more muscle fat for energy during
exercise (European Journal of Applied Physiology, November,
2006). Endurance-trained athletes exercised for three hours to
empty sugar and fat reserves from their muscles. Then they ate
a high-carbohydrate, low-fat diet for 2.5 days or the same diet
with lots of added fat for the last 1.5 days. Athletes who ate the
high-carbohydrate, high-fat diet stored 55 percent more fat in
their muscles and used more than three times as much of that fat
during exercise.
The data on fat storage may have no practical value for
endurance athletes because the authors were not able to show
that the extra fat stored in muscles increased endurance. This is
probably because there is almost an unlimited amount of energy
available from a person’s own body fat. Changing the
percentage of fat use from body fat to muscle fat would not
increase energy sources and therefore would not increase
endurance.
Carbohydrates are another story. Normally there is only
a small amount of carbohydrates stored in the muscles, liver and
bloodstream. Storing extra carbohydrates in muscles is
beneficial because when a person runs out of stored muscle
sugar, his muscles hurt and are more difficult to control. In the
1940s, Per Olaf Ostrand showed that a high carbohydrate diet for
several days before athletic competitions helps a person store
more sugar in muscles, which does increase endurance. Since
then athletes have eaten high-carbohydrate diets before
competition and often have pre-race pasta parties. Subsequent
studies showed that highly-conditioned endurance-trained
athletes can maximally fill their muscles with sugar just by eating
their usual meals and cutting back on their heavy workloads for a
few days before competition.
January 15, 2007