Carbohydrates:
Although studies showed that high carbohydrate intakes increased efficiency of muscular
work, little effort was done to manipulate carbohydrates in diet. To test this, researchers
at Harvard Medical School conducted an experiment at the Boston Marathon in 1924.
Blood samples from the first 20 runners to finish the race were taken, and a link was
found between low glucose levels and symptoms of fatigue, stupor and inability to focus.
The next year, many of these athletes were supplemented with large amounts of
carbohydrates the day before the race. Moreover, sugar candy was provided to the
athletes with instructions to eat them before and during the event. The study showed that
by normalizing blood glucose levels, symptoms of fatigue, stupor and inability to
concentrate were prevented. It was not until the 1960s, however, that research conducted
on carbohydrate by the Swedish team at St. Erik's Sjukhus in Stockholm showed that
high carbohydrate diets heightened endurance performance and ingesting carbohydrates
during exercise delayed fatigue. The early 1970s witnessed a craze in carbohydrate
loading after a study in Scandinavia showed the effect of dietary carbohydrate
manipulation on muscle glycogen and endurance; the higher the glycogen levels were,
the better the work time and better endurance. (see figures 1 & 2)
Figure 2