This article is from the Running FAQ, by Ozzie Gontang with numerous contributions by others.
Nutrition in athletics is a very controversial topic. However, for an
athlete to have confidence that his/her diet is beneficial he/she must
understand the role each food component plays in the body's overall makeup.
Conversely, it is important to identify and understand the nutritional
demands on the physiological processes of the body that occur as a result
of racing and training so that these needs can be satisfied in the
For the above reasons, a basic nutrition primer should help the athlete
determine the right ingredients of his/her diet which fit training and
racing schedules and existing eating habits. The body requires three basic
components from foods: 1) water; 2) energy; and 3)nutrients.
Water is essential for life and without a doubt the most important
component in our diet. Proper hydrations not only allows the body to
maintain structural and biochemical integrity, but it also prevents
overheating, through sensible heat loss(perspiration). Many *runners* have
experienced the affects of acute fluid deficiency on a hot day, better
known as heat exhaustion. Dehydration can be a long term problem,
especially at altitude, but this does not seem to be a widespread problem
among *runners* and is only mentioned here as a reminder (but an important
Energy is required for metabolic processes, growth and to support physical
activity. The Food and Nutrition Board of the National Academy of Sciences
has procrastinated in establishing a Recommended Daily Allowance(RDA) for
energy the reasoning being that such a daily requirement could lead to
overeating. A moderately active 70kg(155lb) man burns about 2700 kcal/day
and a moderately active 58kg(128lb) woman burns about 2500 kcal/day.
It is estimated that runners burn XXXX kcal/min or about XXX-XXX kcal/hr
while *running* (this is obviously dependent on the level of exertion).
Thus a three hour training *run* can add up to XXXX kcals(the public knows
these as calories) to the daily energy demand of the *runner*. Nutritional
studies indicate that there is no significant increase in the vitamin
requirement of the athlete as a result of this energy expenditure.
In order to meet this extra demand, the *runner* must increase his/her
intake of food. This may come before, during or after a *run* but most
likely it will be a combination of all of the above. If for some reason
extra nutrients are required because of this extra energy demand, they will
most likely be replenished through the increased food intake. Carbohydrates
and fats are the body's energy sources and will be discussed shortly.
This is a broad term and refers to vitamins, minerals, proteins,
carbohydrates, fats, fiber and a host of other substances. The body is a
very complex product of evolution. It can manufacture many of the resources
it needs to survive. However, vitamins, minerals and essential amino
acids(the building blocks of proteins) and fatty acids cannot be
manufactured, hence they must be supplied in our food to support proper
Vitamins and Minerals
No explanation needed here except that there are established RDA's for most
vitamins and minerals and that a well balanced diet, especially when
supplemented by a daily multivitamin and mineral tablet should meet all the
requirements of the cyclist.
Proper electrolyte replacement(sodium and potassium salts) should be
emphasized, especially during and after long, hot rides. Commercially
available preparations such as Exceed, Body Fuel and Isostar help replenish
electrolytes lost while *running*.
Food proteins are necessary for the synthesis of the body's
skeletal(muscle, skin, etc.) and biochemical(enzymes, hormones,
etc.)proteins. Contrary to popular belief, proteins are not a good source
of energy in fact they produce many toxic substances when they are
converted to the simple sugars needed for the body's energy demand.
Americans traditionally eat enough proteins to satisfy their body's
requirement. All indications are that increased levels of exercise do not
cause a significant increase in the body's daily protein requirement which
has been estimated to be 0.8gm protein/kg body weight.
Carbohydrates are divided into two groups, simple and complex, and serve as
one of the body's two main sources of energy.
Simple carbohydrates are better known as sugars, examples being fructose,
glucose(also called dextrose), sucrose(table sugar) and lactose(milk
The complex carbohydrates include starches and pectins which are
multi-linked chains of glucose. Breads and pastas are rich sources of
The brain requires glucose for proper functioning which necessitates a
carbohydrate source. The simple sugars are quite easily broken down to help
satisfy energy and brain demands and for this reason they are an ideal food
during racing and training. The complex sugars require a substantially
longer time for breakdown into their glucose sub units and are more suited
before and after riding to help meet the body's energy requirements.
Fats represent the body's other major energy source. Fats are twice as
dense in calories as carbohydrates(9 kcal/gm vs 4 kcal/gm) but they are
more slowly retrieved from their storage units(triglycerides) than
carbohydrates(glycogen). Recent studies indicate that caffeine may help
speed up the retrieval of fats which would be of benefit on long rides.
Fats are either saturated or unsaturated and most nutritional experts agree
that unsaturated, plant-based varieties are healthier. Animal fats are
saturated(and may contain cholesterol), while plant based fats such as corn
and soybean oils are unsaturated. Unsaturated fats are necessary to supply
essential fatty acids and should be included in the diet to represent about
25% of the total caloric intake. Most of this amount we don't really
realize we ingest, so it is not necessary to heap on the margarine as a
balanced diet provides adequate amounts.