Diet and Nutrition
Carbohydrate loading or Glycogen loading is a concept derived from research published in Sweden by Drs. Saltin and Hermanson in 1967. Their work lead to a deluge of muscle glycogen and endurance performance studies throughout the world.
Using muscle biopsy techniques they studied athletes under a variety of dietary and athletic endurance protocols. It was shown that significant increases in muscle glycogen (the muscle storage form of glucose) could be achieved by increasing the carbohydrate intake over several hours to days before endurance performances.
In fact, these developed glycogen levels were optimum when the high carbohydrate diet was preceded by prolonged (over one hour) exhaustive exercise thus depleting the muscle glycogen stores.
This evidence and several other similar studies lead to the indiscriminate practice of "carbo-loading" prior to all kind of competitions. It also lead to a plethora of supplement products designed to "optimize" these glycogen stores.
The fallacy of such practices are based on:
Other issues or concern are:
As far back as 1939 it was shown by Christensen and Hansen of Sweden that a high carbohydrate meals immediately prior to a "strenuous" athletic competition impaired performance.
There is evidence that if blood glucose levels can be maintained, muscle glycogen can be spared and therefore lead to longer, high intensity performances during endurance events exceeding one hour.
My advice is to maintain good muscle glycogen levels with 40 percent of calories coming from complex carbohydrates; observe good recovery practices (see article on what to eat for optimum performance) and during long endurance performances consume a high quality sport drink to maintain the blood glucose levels.
Dr. L. Lee Coyne, the Healthy Professor, is a nutritional consultant, lecturer and author of Fat Won't Make You Fat and the LeanSeekers nutrition program.