Carbohydrates
Carbohydrates are classified as either "simple" or
"complex". Some common simple carbohydrates include
glucose, fructose, and sucrose, and are typically
associated with sweet foods and ripe fruits. The complex
carbohydrates are either digestible (starches) or
indigestible (fiber). The digestible complex carbohydrates
are ultimately "digested" to the simple carbohydrate
glucose when they are consumed. While the ultimate "fuel"
for muscles is glucose, complex carbohydrates usually carry
with them other nutrients, such as B vitamins, which are
necessary for muscles to get energy from the foods we’ve
eaten. Simple carbohydrates (sugars) on the other hand, do
provide energy but may not contain the other nutrients
needed to use this energy. Therefore, it is generally
recommended that athletes consume no less than 60% of total
calories from carbohydrates, and no more than 10% of these
calories in the form of simple carbohydrates. Good sources
of carbohydrates include pasta, bread, cereal, legumes
(beans), fruits, and vegetables.
Glycogen is the storage form of glucose, and it is called
upon when muscles need more fuel. Glycogen is needed for
both endurance and strength events, but the human body has
a limited capacity to store it. Therefore, even though
athletes need a lot of it we only have a limited supply.
Therefore, it is important to take every opportunity to
keep this glycogen "fuel tank" full by making carbohydrates
a main part of the foods usually consumed, and by eating
carbohydrates before, during, and immediately after
exercise. Providing a constant supply of carbohydrates is
the best, simplest, and safest means of "glycogen loading".
Because glycogen is only efficiently stored when an athlete
is well hydrated, it is also important to make certain that
plenty of fluids are consumed while eating carbohydrates.
This is a list of some commonly consumed foods with the
distribution of carbohydrate, protein, and fat:
(Kcal=Calories)
Food
Calories % Carbohydrate % Protein % Fat
1 raw apple
84
100
0
0
10 grapes
36
100
0
0
1 cup orange juice 104
96
4
0
1 oz Rice Krispies 108
93
7
0
1 baked potato 148
92
8
0
1 banana
105
89
3
7
1 cup spaghetti with sauce
198
79
1 bagel
198
77
1 slice bread
69
1 oz Cheerios 114
70
12
14
75
9
9
12
14
13
16
Protein
Protein is a part of muscles, bone, hemoglobin, myoglobin,
hormones, antibodies, and enzymes, and makes up about 45%
of the human body. There is no question that it is an
important constituent of the diet, but the amount of
protein we actually need for activity and health is
considerably less than many people think we need.
The requirement for protein is dependent on total energy
intake, the amount of training an athlete does, and the
intensity of that training. Of these factors, the most
important one is total energy (calorie) intake. Increasing
energy intake from carbohydrate improves protein
utilization, while lowering energy intake to a level below
the amount needed causes increased protein losses and
breakdown. Therefore, one of the best ways to make certain
protein status is OK is to make certain enough total energy
is consumed to maintain activity and growth requirements.
Muscle is approximately 70% water and only about 20%
protein. Therefore, increasing muscle mass requires extra
water, extra energy in the form of carbohydrates (to
maintain the needs of that extra muscle), and a little
extra protein. In fact, for an athlete increasing muscle
mass at an extraordinarily high rate of 1 kg/week (2.2 lbs
of extra muscle per week), only 4 extra ounces of meat per
day would be needed. In most surveys that have been done on
athletes, protein intake from food far exceeds
requirement. The generally accepted athlete requirement
for protein is between 1.5 and 2.0 grams per kilogram of
body weight. Many studies show that athletes commonly
consume well over 3.0 grams per kilogram of body weight.
For athletes who take unnecessary protein powders and amino
acid supplements, the intake of protein is often higher
than 3.5 grams per kilogram of body weight. However,
carbohydrate and water intake is typically lower than the
amount needed to maintain or increase muscle mass. It also
appears that those athletes (body builders, weight lifters,
football players, etc) who generally consume supplements of
protein and amino acids (components of protein) are those
who need supplements the least.
High sources of protein include meat, poultry, fish, and
eggs. However, vegetarians can obtain adequate protein by
combining non-meat items. For instance, combining legumes
(beans) and cereals (rice or corn) creates a protein
combination of high quality. However, animal proteins
provide numerous other nutrients (including iron and zinc)
that are more difficult to obtain elsewhere unless the diet
is very carefully planned.
The bottom line is this: If you consume enough energy from
carbohydrates, then the protein you consume will be used
for all the valuable protein related functions, such as
synthesis and maintenance of muscle, synthesis of creatine,
and the creation of hormones and enzymes. However, without
enough carbohydrate energy, the consumed protein will be
'burned' as fuel rather than used for these other critical
functions. Burning protein as fuel causes increased water
loss that can increase the risk of dehydration (a major
factor related to poor performance in athletes.)
Fat
Fat is an energy source that provides the essential fatty
acid and carries fat soluble vitamins (vitamins A, D, E,
and K) . In general, people eat a great deal more fat than
is desirable for health or necessary for athletic
performance. Americans typically consume foods that provide
well over 35% of total calories from fat, and surveys of
athletes indicate that their average fat intake is only
slightly lower. Athletes should strive to have a fat intake
that does not exceed 25% of total calories. To achieve this
goal, it is important to know what foods are high in fat
and to know some strategies that might make it easier to
reduce fat intake. The good news is that, because fat is
such a concentrated source of energy, reducing fat intake
makes it possible for you to eat much more food!
Fats are a natural component of some foods, such as whole
milk, meat, nuts, and cheese, and they are often added in
food processing to make potato chips, other fried foods,
and desserts. Many people don’t realize that whole milk,
even though it contains only 3.8% fat by volume, derives
over 50% of its calories from fat. Even 2% milk, which is
touted as a "low fat" product, derives over 32% of its
calories from fat. Skim milk, on the other hand, contains
all of the nutrients of whole milk but with NO fat. A
simple strategy for reducing fat intake is to follow these
three simple rules:
Consume little or no fried foods (the baked, broiled, or
boiled equivalent is OK).
Stay away from prepared meats (bologna, salami, bacon,
sausage, etc.). These are typically very high in fat.
Limit the consumption of visible fats (butter, margarine,
fat surrounding steak, chicken skin, etc.)
Fats are metabolized during exercise, but it takes time and
aerobic training to become an efficient fat "burner".
In
addition, excess dietary fat is very efficiently and easily
converted to stored body fat. Therefore, a combination of
frequent exercise and lower dietary fat are both needed to
assure a good body fat level. The good news is you don't
have to totally eliminate fat from your diet. Rather, take
some simple steps to reduce the fat in your diet.
Some 'diets' suggest that increasing fat intake is good for
athletic performance. In fact, all the good studies
strongly suggest that higher carbohydrate intake and lower
fat intake are important for optimizing athletic
performance. So, don't be taken in by the fad diets. Eat a
reasonably lower fat diet with plenty of carbohydrates to
fuel activity.
Fluids
Water may be the most critical single nutrient needed to
ensure that the athlete can perform up to his/her trained
or conditioned ability. Since heat production is increased
with ALL forms of exercise, it is necessary for athletes to
maintain water balance so this excess heat can be
dissipated through the production of sweat. With the
evaporation of sweat, heat is lost from the blood that
circulates near the skin. The rate of sweat loss varies
between people and with the temperature, but it is common
to see water losses of up to 3 liters (over 6 quarts!) per
hour in trained athletes exercising in hot and humid
environments. Water losses that represent 6% of body weight
may occur with 2 hours of training in high heat.
DEHYDRATION occurs when fluid losses are greater than 1% of
body weight, and athletic ability is impaired with a 2%
loss of body weight. This means a 100 lb athlete who loses
2 pounds during exercise may no longer be performing up to
his/her trained ability because of the excessive water
loss. Typical symptoms of inadequate fluid intake during
exercise include: thirst, fatigue, loss of coordination,
mental confusion, irritability, dry skin, elevated body
temperature, and reduced urine output. Heat stroke, caused
by severe heat injury and inadequate hydration, has a
mortality rate of 80%. To assure that an athlete learns to
drink sufficient amounts of fluid during exercise, weight
should be taken before exercise and after exercise. The
difference in weight in pounds is equal to the the amount
of fluid, in pints, the athlete should have consumed during
exercise. For instance, an athlete losing 4 pounds during
exercise should learn to consume 4 additional pints of
fluid during that activity.
GENERAL GUIDELINES:
Adequate daily consumption of fluids to avoid thirst.
Limit consumption of caffeine and alcohol containing
fluids. They act as diuretics and can increase fluid loss.
Drink at least 8 to 16 oz of fluid 2 hours before exercise
Drink at least 4 to 8 oz of fluid immediately before
exercise
Drink at least 4 to 8 oz of fluid every 15 to 20 minutes
during exercise (whether thirsty or not)
Drink at least 8 to 16 oz of fluid after exercise
Drink at least 8 oz of fluid with each meal
Drink at least 8 oz of fluid between meals.
Note: Sports drinks should be used in place of water,
regardless of the length or intensity of the activity.
They encourage drinking, and improve the delivery of both
carbohydrate and water to the muscles. They also,
importantly, help to maintain blood volume.
Vitamins and Minerals
The following covers b-vitamins, vitamin C, calcium, and
iron. There are many other vitamins and minerals of equal
importance in human nutrition. These are covered because
they are either closely linked to physical activity, or are
related to nutrient risks commonly faced by athletes.
B-VITAMINS
B-vitamins have a well-established role in energy
metabolism and muscle function and, because of this role,
are frequently taken in supplement form by athletes. These
vitamins, which include thiamin (B-1), riboflavin (B-2),
niacin, pyridoxine (B-6), folacin, cyanocobalamin (B-12),
pantothenic acid, and biotin, work together in energy
metabolic processes. Taking supplements, in the absence of
a known deficiency, does NOT improve athletic potential,
and may introduce harmful side effects. Therefore, a
balanced diet is the best approach to making certain you
get enough of the B-vitamins.
Thiamin Food Sources: Liver, pork, lean meats, wheat germ,
whole grains, enriched breads, and cereals.
Riboflavin Food Sources: Milk and milk products, liver,
enriched breads, and cereals.
Niacin Food Sources: Liver, poultry, fish, peanut butter.
Pyridoxine Food Sources: Liver, herring and salmon, wheat
germ and whole grains, lean meats.
Folacin Food Sources: Liver, wheat bran, whole grains,
spinach and other green leafy vegetables, legumes, orange
juice.
Cyanocobalamin Food Sources: Foods of animal origin,
specially prepared fermented yeasts, and fortified soy
products.
Biotin Food Sources: Egg Yolk, liver, and legumes.
Pantothenic Acid Food Sources: Eggs, liver, wheat bran,
peanuts, legumes, lean meats, spinach, and other
vegetables.
VITAMIN C
Vitamin C is involved in the manufacture of collagen, a
connective tissue protein, and is also involved in the
manufacture of thyroxin, a hormone that controls the rate
at which energy is used. Vitamin C is also involved in the
absorption of iron, resistance to infection, and metabolism
(breakdown and build-up) of amino acids, the building
blocks of protein.
It is not clear from studies whether a marginal vitamin C
status impairs athletic performance or work capacity.
Therefore it does not appear that taking supplements, even
when a good diet is consumed, is necessary for optimizing
athletic performance. Toxicity symptoms to excessive
vitamin C intake are rare.
Symptoms of vitamin C deficiency include:
Microcytic anemia (small and inadequate red blood cells,
limiting oxygen carrying capacity.)
Purpura (small red dots appearing at the base of hair
follicles, due to hemorrhage.)
Easy hemorrhaging Depression
Frequent infections
Symptoms of vitamin C toxicity (excess) include:
Early red-cell breakdown
Nausea
Frequent urination
Abdominal cramps
Diarrhea
Good Food Sources of Vitamin C include fresh fruits, fruit
juices, an vegetables. Bean sprouts are also good sources.
CALCIUM
While the recommendation for calcium is between 800 to
1,500 mg/day many athletes have an intake that is far less
than this amount. Further, there is evidence that the
current requirement is actually lower than it should be.
These factors, coupled with the fact that exercise
increases bone stress, suggest that more athletes should be
concerned about their level of calcium intake. Inadequate
calcium intake can increase the risk of stress fractures
and, if there is inadequate intake during growth, may
increase the risk of early osteoporosis (bone disease)
later in life. Bones consist of living cells that are
constantly changing (just like all other cells in the
body). Providing enough calcium helps to assure that the
bones will change in a positive direction.
Major functions of calcium include:
Bone formation and bone strength
Nerve impulse transmission
Muscle contraction
Blood clotting
pH control
Blood pressure control
The following foods contain about the same amount of
calcium (297mg) as 8 oz (1 cup) of milk:
Cheddar Cheese l.5oz
Cottage Cheese 2 cups
Yogurt 1 cup
Processed Cheese 1.5 slices
Ice Cream 1.5 cups
Ice Milk 1.5 cups
Tofu 8 oz
Broccoli 2 cups
Collard Greens 1 cup
Turnip Greens 1 cup
Mustard Greens 1.5 cups
Salmon 4 oz
Sardines 2.5 oz
Orange Juice w/calcium 1 cup
Common calcium supplements and elemental calcium
concentration:
Calcium gluconate 9% calcium
Calcium lactate 13% calcium
Calcium carbonate 40% calcium
IRON
Iron deficiency may lower athletic performance because of
its involvement in carrying oxygen to cells and removing
carbon dioxide. Many athletes may be at risk f or iron
deficiency because of poor iron intake, poor iron
absorption, loss of iron in sweat, blood loss in the GI
tract, and red blood cell breakdown.
A condition called "sports anemia" has been reported in
athletes, and is most associated with increased red blood
cell breakdown and lower hemoglobin concentration when an
exercise program is initiated. However, "sports anemia"
appears to be a transient condition that disappears when
red cell production has an opportunity to catch up to the
increased blood volume that occurs with exercise.
It appears that female and growing athletes are more at
risk for iron deficiency than male or grown athletes.
Vegetarian athletes also appear to be at increased risk of
deficiency.
The following recommendations should help to reduce the
risk of iron deficiency:
Consume lean cuts of meat (dark poultry or red meat) 3 to 4
times
per week.
Consume enriched grains and cereals (breads, pastas, etc.)
regularly
Consume vitamin C containing foods (fruits, fruit juices)
with grains and vegetables. The vitamin C enhances iron
absorption from these foods.
Consume tea, coffee, and all-bran products in moderation.
These foods contain substances that may inhibit iron
absorption.
Women of child-bearing age may require a low-level
supplement of iron to assure an adequate intake (consult
your physician).
Pre-Game Meal
In general, the pre-exercise meal should focus on the
provision of carbohydrates and fluids. Provision of a
nutritionally balanced meal should not be a major concern
at this time, especially if the athlete is well-nourished
most of the time. There are several goals for the preexercise meal, including:
Sufficient Energy - Making certain the athlete obtains
sufficient energy to see him/her through much of the
exercise/competition that will follow the meal. Inadequate
energy may lead to light-headedness, blurred vision, early
fatigue, and loss of competitive attitude.
Prevent Feelings of Hunger - When the athlete feels hungry,
this is a sign that blood sugar may be low. Low blood
sugar could impair muscle function and is related to
central nervous system fatigue.
Drink Fluids - Provision of sufficient fluids to make
certain the athlete begins exercise in a fully hydrated
state is important for athletic performance and endurance.
Eat Familiar Foods - Only consume foods you know make you
feel good and don't cause any kind of GI distress. If
you're competing in a country you've never been to, there
is a big temptation to try unfamiliar local foods. Don't
do that until after the competition.
Avoid Large Amounts of Raw Fruits and Vegetables - Raw
fruits and vegetables may be gas forming, and lead to GI
distention and distress. In particular, foods in the
cabbage family (cabbage, Brussel sprouts, mustard greens,
kholrabi, etc.) appear to be a particular problem. Eating
cooked vegatables or fruit juices do not appear to lead to
problems.
TIMING: There should be adequate time for food to leave the
stomach before the initiation of exercise. Because fats
cause a delay in gastric emptying, fat in the pre-exercise
meal should be kept as low as possible. Ideally, a highcarbohydrate meal should be finished 3.5-4.0 hours before
exercise if the meal is large (lots of food); 2.0-3.0 hours
before exercise if the meal is small. If fat constitutes
more than 25% of total energy in the meal, the timing of
the meal should be changed so that it moves further from
the time of exercise. Light, carbohydrate snacks (crackers,
etc.) may be consume within 1 hour of exercise. Sports
beverages may be consumed at any time before and during
exercise.
Athletes with nervous stomachs may not tolerate food well
before exercise or competition, yet they are still in need
of energy to fuel their muscles. One solution is to make
certain they consume very large amounts of carbohydrates
the day before competition, followed by small snacks of
carbohydrates and fluids on the day of competition. Some
athletes may also tolerate liquid meal replacements well,
but these should not be experimented with on a day of
competition.
SAMPLE PRE-EXERCISE MEAL: (Calories)
2 Cups of Spaghetti (395 calories)
3/4 Cup of Meatless Spaghetti Sauce (203 calories)
2 Tbsp of Parmesan Cheese (46 calories)
3/4 Cup Tossed Salad (1 calorie)
1 Tbsp Low Fat Salad Dressing (67 calories)
2 Dinner Rolls (156 calories)
1 Cup Apple Juice (116 calories)
2 Cups Water (0 calories)
Totals: 69% Carbs; 11% Protein; 20% Fat; 1,000 Cal
Post-Game Meal
Muscles are very receptive to replacing stored muscle
energy (glycogen) within the first 1 or 2 hours after
exercise because of a high level of circulating enzyme
(glycogen synthetase) that aids this process. For those
athletes who work out on consecutive days or who have
multi-day consecutive competitions, replenishing energy
stores immediately after exercise is a good strategy for
assuring an optimal energy level on the following day.
Also, fluids must be replaced as soon after exercise as
possible.
Ideally, the athlete should consume 200 to 400 calories
from carbohydrates immediately following activity, and then
an additional 200-400 calories from carbohydrates within
the next several hours. For those athletes who have
difficulty eating foods immediately following exhaustive
exercise, try high-carbohydrate liquid supplements. These
have the added benefit of also providing some needed
fluids.
Examples of some high-carbohydrate foods:
Food
Calories % Carbohydrate
1 Bagel
165
76
2 Slices Bread
135
81
1 Cup Pasta
215
81
3 Cups Popcorn
70
79
1 Baked Potato
100
88
1 Apple
80
100
1 Orange
65
100
1 Cup Vegetable Juice
55
93