Software Vault: The Gold Collection/Software Vault - The Gold Collection (American Databankers) (1993).ISO/cdr13/nutritn.zip/COMPET.NUT

Text File | 1993-05-12 | 12KB | 235 lines

     Here's the original version of an article in the Feb 91
VeloNews. Compare the two to see what an editor can do to a story
(You tell me which is the better).

Roger Marquis
____________________________________________________________________

                      COMPETITIVE NUTRITION

     It's sometimes difficult to assess the effect of diet on
athletic performance. While some riders seem to do well no matter
what they eat many unknowingly handicap themselves with less than
optimal eating habits both on and off the bike.
     Most elite cyclists do watch their diets carefully and will
attest to the value of eating intelligently. Experienced riders
are usually better able than novices to sense the subtle physical
signs of different dietary regimes.

ON THE BIKE
FOOD
        During any workout, your blood sugar level primarily
determines how well you feel and perform; therefore it is vitally
important to eat during rides. If you burn large numbers of
calories and do not replace them, your blood sugar level will
begin to drop and you will feel tired. Most riders misinterpret this
fatigue as lack of endurance, more likely they just have not
eaten enough.
     If you eat every 15 to 20 minutes after the first 45 minutes
of your ride, you can avoid this problem. That means remembering
to bring food on rides and remembering to eat lightly and
regularly. Bananas, fig bars, Powerbars, fruit juice diluted with
water, etc., all are easily available and easily digested on the
bike. Avoid high-fat foods, they can slow you down, and simple
sugars that can cause an insulin reaction, leaving you with lower
blood sugar levels than before you ate.
     Eating while working-out does not come naturally to most
people. The physical stress of exercise depresses the hunger
center of the brain. Especially during extreme effort, you will
not become hungry until your blood sugar has dropped dangerously
low. So if, during a hard ride, your blood sugar level falls low
enough to cause hunger, you've waited too long. You may not be
able to eat and continue your ride, you may need a prolonged (12+
hours) rest.
      If you don't eat enough during a ride, you will "bonk". one
time or another every serious cyclist experiences it. When your
blood sugar falls so low that further exercise becomes difficult,
you have bonked. If it happens to you find something sweet to eat
right away and ride straight home the easiest possible way. Do not
wait to eat and don't ride further than you have to. Your body
can become so stressed from bonking that you may wake up the next
morning feeling sick. Even if you do not get sick, you probably
won't derive any training effect from the workout. Recovery can take
so long you may notice a decrease in your fitness rather
than an increase - even if the workout had seemed high quality.
     Normal levels of blood sugar (glucose) are essential for
metabolizing fat. When blood sugar runs low you cannot burn fat
to compensate for it. This becomes especially important as fat
utilization rises steadily after the first thirty minutes of
exercise. In order to burn fat you need to ride for at least
half an hour - without getting hungry doing it. You can't train
your body to burn fat by eating less during a workout; you can
only become more efficient at burning fat for fuel by getting
fit. Glucose is also the only fuel the brain can use. Starving
your brain for fuel, you may be unable to think clearly and risk
your own safety.

DRINK
     Thirst is similarly suppressed during strenuous exercise.
Though a highly trained athlete will be better able to judge how
much to drink, large fluctuations in need can occur due to
fatigue, temperature, altitude, humidity, air flow, fitness, food
and the type of fluid consumed. Dehydration can fool you because
it feels exactly like fatigue. Late in a hard ride, when you feel
tired, you may simply be running short on fluids. Don't sell
yourself short, drink up before you get tired.
     A fluid loss of as little as three percent of your total
body weight (4.5 of 150 lbs.) can measurably effect your
performance. Dehydration impairs thermoregulation through reduced
sweating and blood circulation. Your blood gets thicker, creating
cardiac stress and impairing metabolic processes necessary for
physical effort.
     If you lose more than a few pounds on a ride, or more than a
couple of pounds overnight, you probably didn't drink enough.
With experience you should be able to keep within a few pounds of
pre-race weight even on long rides in hot weather.

ELECTROLYTES
     Current research indicates that the most likely reason
electrolytes are eliminated in sweat is to compensate for their
rising concentrations in the blood. The concentration of
electrolytes rises because of a net fluid loss when you drink
less than you sweat. Supplementation with electrolyte-containing
"sports drinks" only raises blood salt levels higher and
increases volemic (as opposed to osmotic, or intra-cellular)
dehydration.
     Many commercial sports drinks offer little more value than
diluted fruit juice. Of all the studies done on sports drinks and
performance only one has shown any effect. The American Dietetic
Association (1981) showed a decrease in the performance of
athletes drinking fluids containing electrolytes when compared
with straight water. Electrolytes pull fluids out of the
bloodstream and deposit them into cells where they are far less
effective in compensating for fluid losses brought about by
sweating and physical effort.
     Overly sweet fluids too, can hurt your performance. Sugar
concentrations over 100 calories per water bottle slow the
absorption of fluid and, except for fructose, can cause an
insulin reaction. The high sugar concentration of some commercial
drinks merely lessens their effectiveness in preventing
dehydration.
     On the other hand, one of the best sources of quick energy
is the water bottle, especially for shorter races. Watch a pro
peleton in Europe: in the final kilometers you will see riders
pulling small flasks out of their pockets and drinking the
contents. These flasks usually contain a dextrose/glucose
solution that quickly and temporarily raises blood sugar. The
extra sugar can be a tremendous advantage in the sprint.
     There is controversy in sports-medical literature these days
about the optimal sugar concentration of fluid taken during
exercise. Most of these studies fail to consider that a less than
maximal rate of absorption may be appropriate if much-needed
calories are also absorbed. Despite the debates, most cyclists
learn by trial and error what fluids work best and in what
quantities.

OFF THE BIKE
PROTEIN
        Many endurance athletes opt for a full-time high
carbohydrate diet. While such a diet might be beneficial before a
competition, it is not a good idea to let daily protein intake
fall below 14% of total calories. Not only is the amino acid pool
tapped for fuel during endurance exercise, amino acids also play
an important role in muscle metabolism (primarily in acid
buffering and the glucose-alanine cycle).
     Among the many disadvantages of a negative nitrogen balance
(protein deficit) are reduced healing and recovery abilities,
immune suppression system and muscle atrophy. Have you noticed
how thin cyclists can get after a few months (or days, in some
cases) of putting in serious miles? Not just low body fat but
honest, muscle and fat, skinny. That kind of weight loss is
undesirable even if it helps you climb better. You lose weight
like that because your muscle tissue is being converted into fuel
(gluconeogenesis) when other sources of energy begin to run low.
This muscle is not regenerated if your amino acid pool is tapped
for energy and your diet is low in protein (measured as percent
of total calories NOT grams per day). You may lose weight but you
will not become a fitter, better rider.
     On the contrary, protein malnutrition will depress your
immune system, retard your recovery from hard workouts, slow
healing and impede many other processes, both physical and
mental, necessary for your athletic success.

FATS
     Though cholesterol levels are rarely a problem for racing
cyclists, a high fat diet can effect performance, especially for
track and criterium riders. Fat is not very nutrient-dense. Those
nine calories per gram displace proteins and carbohydrates and are
rarely high in vitamins or minerals. While fats play an important
role in hormone production and nerve cell function, especially in
children and young adults, the U.S. national average of 40%+ of
calories derived from fat is well over the recommended 25 to 35%.

CARBOS
     Carbohydrates are the tiger in every cyclist's tank. They
are also the best source of fiber. The optimum percentage of
calories derived from carbohydrates is 50% to 60%. The more
complex these carbos are the better. Whole grain breads, pastas,
brown rice, and vegetables like potatoes, peas and corn are the
best sources of quality carbohydrates.
    One way of assuring good blood sugar levels during a race is
by carbohydrate supercompensation or "carbo loading." First you
deplete your body's glycogen stores with a low carbohydrate diet,
tricking your body into storing more glycogen than it normally
would during the next phase, the loading phase, when primarily
complex carbohydrate foods are eaten.
     There is a proven benefit to carbo-loading for single day
events lasting over two hours, but there are also significant
drawbacks. The depletion phase is physiologically stressful. An
elite athlete must train easier during the depletion phase. The
carbo-loaded athlete will also weigh more due to the large
quantities of water stored with each gram of glycogen. This water
will help with hydration later in the race but could be a
hindrance in the event of an intense early effort.

BEFORE AND AFTER THE RIDE
     Drinking before a race or ride is just as important as
drinking during the ride. Just drink a large glass of water or
juice (unsweetened, of course). If you drink coffee or tea with
breakfast drink another glass of water to counteract caffeine's
strong dehydrating effect.
     After a long ride many cyclists notice a significant weight
loss. Ninety-five% of this lost weight is water. To recover
quickly replace the lost fluid by drinking two cups of water
every half hour for every pound you lost. Do not rely on your
sense of thirst. If you delay rehydrating, you will also delay
your recovery.

BREAKFAST
     Amazingly, lots of (non-elite) athletes train before
breakfast or skip breakfast altogether. Skipping the morning meal
is an unproductive habit which should be "unlearned" at the
earliest possible opportunity.
     Think about it: the average human uses more than six hundred
calories during any twelve hour period (including during sleep);
the recovering athlete uses considerably more. Beginning a
workout hundreds of calories in glycogen debt does not lead to a
productive workout. Why be a slave to an unproductive habit? Get
used to eating breakfast. Start with a glass of juice; when
you're comfortable with just the juice, add some toast or oatmeal
or even a breakfast bar. After a few days of eating breakfast any
discomfort should go away and those morning workouts will improve
noticeably.

DIETARY ANALYSIS
     The only way to be sure you're eating well is to do a
dietary analysis. Estimating just doesn't cut it. Write down your
standard diet for three days. Specify the quantities and
descriptions of all meals and snacks. Then: 1) Check out a copy
of the "Nutritive Values of American Foods" and look up the
nutritive values of what you ate. Or, 2) Take your diet list to a
Registered Dietitian for a detailed computer analysis. This is
about the most useful information an athlete can get.
     For the definitive word on nutrition go to the nearest
college bookstore and pick up a copy of "Nutrition for Living"
(Christian, J., Benjamin/Cummings, 1985). This volume serves as
the reference text for most nutrition courses. It is well written
and informative without the biases and inaccuracies often found
in popular books.

_____________________________________________________________________

Roger Marquis   ({berkeley.edu!}well.uucp!marquis)
                (uunet.uu.net!pge!rnd!goldfinger!rnm)