This article is from the Running FAQ, by Ozzie Gontang with numerous contributions by others.
Now that we have somewhat of an understanding of the role each food
component plays in the body's processes let's relate the nutritional
demands that occur during *running* in an attempt to develop an adequate
diet. Basically our bodies need to function in three separate areas which
require somewhat different nutritional considerations. These areas are: 1)
building; 2) recovery; and 3) performance.
Building refers to increasing the body's ability to perform physiological
processes, one example being the gearing up of enzyme systems necessary for
protein synthesis, which results in an increase in muscle mass, oxygen
transport, etc. These systems require amino acids, the building blocks of
proteins. Hence, it is important to eat a diet that contains quality
proteins (expressed as a balance of the essential amino acid sub units
present)fish, red meat, milk and eggs being excellent sources.
As always, the RDA's for vitamins and minerals must also be met but, as
with the protein requirement, they are satisfied in a well balanced diet.
This phase may overlap the building process and the nutritional
requirements are complimentary. Training and racing depletes the body of
its energy reserves as well as loss of electrolytes through sweat.
Replacing the energy reserves is accomplished through an increased intake
of complex carbohydrates(60-70% of total calories) and to a lesser extent
fat(25%). Replenishing lost electrolytes is easily accomplished through the
use of the commercial preparations already mentioned.