This article is from the Bicycles FAQ, by Mike Iglesias 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 cycling 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.
Because the performance phase(which includes both training rides and
racing)spans at most 5-7 hours whereas the building and recovery phases
are ongoing processes, its requirements are totally different from the
other two. Good nutrition is a long term proposition meaning the effects
of a vitamin or mineral deficiency take weeks to manifest themselves.
This is evidenced by the fact that it took many months for scurvy to
show in sailors on a vitamin C deficient diet. What this means is that
during the performance phase, the primary concern is energy replacement
(fighting off the dreaded "bonk") while the vitamin and mineral demands
can be overlooked.
Simple sugars such a sucrose, glucose and fructose are the quickest
sources of energy and in moderate quantities of about 100gm/hr(too much
can delay fluid absorption in the stomach) are helpful in providing fuel
for the body and the brain. Proteins and fats are not recommended because
of their slow and energy intensive digestion mechanism.
Short, one day rides or races of up to one hour in length usually require
no special nutritional considerations provided the body's short term energy
stores (glycogen) are not depleted which may be the case during multi-day
Because psychological as well as physiological factors determine performance
most cyclists tend to eat and drink whatever makes them feel "good" during a
ride. This is all right as long as energy considerations are being met and
the stomach is not overloaded trying to digest any fatty or protein containing
foods. If the vitamin and mineral requirements are being satisfied during the
building and recovery phases no additional intake during the performance phase