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Rec.Bicycles Frequently Asked Questions Posting Part 5/5
Section - 9.20 Nutrition

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Oh well, I have been promising to do this for a while and given the present
discussions on nutrition, it is about the right time.  This article was
written in 1980 for Bicycling Magazine.  It has been reprinted in over 30
publications, been the basis for a chapter in a book and cited numerous
other times.  I guess somebody besides me thinks its OK.  If you disagree
with any points, that's fine, I just don't want to see people take exception
based on their own personal experiences because everyone is different and
psychological factors play a big role(much bigger than you would think)
on how one perceives his/her own nutritional requirements.  Remember that
good nutrition is a LONG TERM process that is not really affected by short
term events(drinking poison would be an exception).  If it works for you
then do it!!!  Don't preach!!!!



		BASIC NUTRITION PRIMER

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 athlete's diet.
 
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
 
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 cyclists 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 cyclists and is only mentioned here as a reminder(but
an important one).
 
ENERGY
 
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 cyclists burn 8-10 kcal/min or about 500-600
kcal/hr while riding(this is obviously dependent on the level of
exertion).  Thus a three hour training ride can add up to 1800
kcals(the public knows these as calories) to the daily energy demand
of the cyclist.  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 cyclist must increase his/her
intake of food.  This may come before, during or after a ride 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. 
 
NUTRIENTS
 
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 health.
 
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 riding.
 
Proteins
 
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
 
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 sugar).
 
The complex carbohydrates include starches and pectins which are multi-linked
chains of glucose.  Breads and pastas are rich sources of complex
carbohydrates.
 
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
 
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.
 
WHAT THE BODY NEEDS
 
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
 
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.
 
Recovery
 
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.
 
Performance
 
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
events.
 
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
is necessary.
 
 
IMPLICATIONS
 
Basically, what all this means is that good nutrition for the cyclist is
not hard to come by once we understand our body's nutrient and energy
requirements.  If a balanced diet meets the RDA's for protein, vitamins
and minerals as well as carbohydrate and fat intake for energy then everything
should be OK nutritionally.  It should be remembered that the problems
associated with nutrient deficiencies take a long time to occur.  Because
of this it is not necessary to eat "right" at every meal which explains
why weekend racing junkets can be quite successful on a diet of tortilla
chips and soft drinks.  However, bear in mind that over time, the body's
nutritional demands must be satisfied.  To play it safe many cyclists
take a daily multivitamin and mineral supplement tablet which has no adverse
affects and something I personally recommend.  Mega vitamin doses(levels
five times or more of the RDA) have not been proven to be beneficial and may
cause some toxicity problems.
 
GREY NUTRITION
 
"Good" nutrition is not black and white.  As we have seen, the body's
requirements are different depending on the phase it is in.  While the
building and recovery phases occur somewhat simultaneously the performance
phase stands by itself.  For this reason, some foods are beneficial during
one phase but not during another.  A good example is the much maligned
twinkie.  In the performance phase it is a very quick source of energy
and quite helpful.  However, during the building phase it is not necessary
and could be converted to unwanted fat stores.  To complicate matters, the
twinkie may help replenish energy stores during the recovery phase however,
complex carbohydrates are probably more beneficial.  So, "one man's meat
may be another man's poison."
 
NUTRIENT DENSITY
 
This term refers to the quantity of nutrients in a food for its accompanying
caloric(energy) value.  A twinkie contains much energy but few vitamins and
minerals so has a low nutrient density.  Liver, on the other hand, has a
moderate amount of calories but is rich in vitamins and minerals and is
considered a high nutrient density food.
 
Basically, one must meet his/her nutrient requirements within the
constraints of his/her energy demands.  Persons with a low daily
activity level have a low energy demand and in order to maintain their
body weight must eat high nutrient density foods.  As already
mentioned, a cyclist has an increased energy demand but no significant
increase in nutrient requirements.  Because of this he/she can eat
foods with a lower nutrient density than the average person.  This
means that a cyclist can be less choosy about the foods that are eaten
provided he/she realizes his/her specific nutrient and energy
requirements that must be met. 
 
BALANCED DIET
 
Now, the definition of that nebulous phrase, "a balanced diet".  Taking into
consideration all of the above, a diet emphasizing fruits and vegetables
(fresh if possible), whole grain breads, pasta,  cereals, milk, eggs, fish and
red meat(if so desired) will satisfy long term nutritional demands.
These foods need to be combined in such a way that during the building and
recovery phase, about 60-70% of the total calories are coming from carbohydrate
sources, 25% from fats and the remainder(about 15%) from proteins.
 
It is not necessary to get 100% of the RDA for all vitamins and minerals
at every meal.  It may be helpful to determine which nutritional
requirements you wish to satisfy at each meal.  Personally, I use breakfast
to satisfy part of my energy requirement by eating toast and cereal.  During
lunch I meet some of the energy, protein and to a lesser extent vitamin and
mineral requirements with such foods as yogurt, fruit, and peanut butter
and jelly sandwiches.  Dinner is a big meal satisfying energy, protein,
vitamin and mineral requirements with salads, vegetables, pasta, meat and
milk.  Between meal snacking is useful to help meet the body's energy
requirement.
 
CONCLUSION
 
All this jiberish may not seem to be telling you anything you couldn't
figure out for yourself.  The point is that "good" nutrition is not
hard to achieve once one understands the reasons behind his/her dietary
habits.  Such habits can easily be modified to accommodate the nutritional
demands of cycling without placing any strict demands on one's lifestyle.

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Top Document: Rec.Bicycles Frequently Asked Questions Posting Part 5/5
Previous Document: 9.19 Reflective Tape
Next Document: 9.21 Nuclear Free Energy Bar Recipe

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Last Update March 27 2014 @ 02:11 PM