Nutrition by pengxiang



   KNR 240
 What are the different kinds of nutrients,
  and what functions do they perform in the
 How does the body use the foods we
  consume for fuel?
 What percentages of calories come from
  protein, fats, and carbohydrates in the
  average American diet, and what
  percentages of these nutrients are
 What guidelines have been developed
  to help people choose a healthy diet,
  avoid nutritional deficiencies, and
  protect themselves from diet-related
  chronic diseases?
 How can people adapt nutritional
  information to their own lives and
Nutrition is:
 A vitally important
  component of
 Closely linked with                      MAJOR CHRONIC DISEASE
  certain diseases,                                RISK

  disabling conditions,
  and other health         HEART DISEASE   CANCER        STROKE    DIABETES
So, the goals of this section are to:
 Understand the basic principles of nutrition.
 Learn the six classes of essential nutrients,
 Learn the role of these essential nutrients
  in the body.
 Understand the guidelines that are
  available to help YOU design a food plan
  for health and wellness for yourself…..
 Understand the guidelines that are
  available to help YOU design a food plan
  for health and wellness for your athletes…
   Proteins
   Carbohydrates
   Fats
   Vitamins
   Minerals
   Water

Are nutrients that we
 must include in our diet.
 Our body does not
 manufacture them.
 Nutrients are released into the body
  by the process of DIGESTION
 The Energy in Foods is measured in
   1 kcal represents the amount of heat it
    takes to raise the temp. of 1 kg of water
    1 degree C.
The Process of Digestion
  3 PROVIDE          3 DO NOT
    fat                vitamins
    protein            minerals
    carbohydrates      water
Food Energy
 Fats
   Provide the most energy.
   9 calories per gram.
 Carbohydrates
   Provide 4 calories per gram
 Proteins
   Provide 4 calories per gram.
 Alcohol
   Although alcohol is not an essential nutrient, it
    does provide energy.
   Alcohol provides 7 calories per gram
•Although vitamins, minerals,
and water do not provide
energy, they are still VITAL!
•The body is approximately 60%
water, and can survive only a
few days without it.
•All foods are combinations of
the different kinds of nutrients.
Energy and ATP Production
 Metabolism is---‖The sum of all the
  chemical processes necessary to
  maintain the body.‖
 Energy is required to fuel vital body
 The rate at which your body uses
  energy (its metabolic rate) depends
  on your level of activity.
So, where does the energy come
 The body converts chemical energy
  from food into substances that cells
  can use as fuel.
 These fuels can be used immediately
  or stored.
•During digestion, most
carbohydrates are broken down
into glucose.
•Some glucose remains in the
blood and some is converted to
glycogen and is stored in the
liver, muscles, and kidneys.
•Remaining glucose is converted
to fat and stored in adipose.
 Used primarily for building of new
 Can be broken down for energy when
  other fuels not available.
 Excess can be converted and stored
  as fat.
 Excess fat is stored as fat.
 Adenosine triphosphate- Is the basic form of
  energy used by the cells.
 ATP is ―The energy currency of cells‖
 When a cell needs energy, it breaks down ATP,
  which is a process that releases energy in the only
  form the cell can use directly.
 Cells do store a minute amount of ATP, but when
  more is needed, it is created through the chemical
  reactions that break down the body’s stored fuels-
  glucose, glycogen, and fat.
 Metabolic pathway map.
Exercise and the three energy
 The muscles in your body have three
  energy systems by which they can
  create ATP and fuel cellular activity.
 These systems use different fuels and
  chemical processes, and they perform
  different, specific functions during
Immediate energy system
ATP-CP stores
   Very short duration (<10sec.)
   Very high intensity
   Rapid ATP production
   Uses existing ATP, CP
   Anaerobic.
Non-oxidative (Anaeroic)
Lactate Path
 Short duration (10sec to 2 min.)
 High intensity
 Rapid rate of production of ATP
 Glucose and glycogen used in process
  called glycolysis
 Anaerobic-no oxygen used.
 Produces lactic acid
Oxidative (Aerobic)
 Used in activities longer than 2 minutes
 Low to moderate intensity
 Slower production of ATP, but is prolonged
 Fuel used is glycogen, glucose, fat, and
 Oxygen is required (aerobic)
 ATP production occurs in the mitochondria.
  The mitochondria can use either glucose or
  fats to produce ATP. The fuel used
  depends on the intensity of the exercise.
Oxidative-Aerobic continued
 Maximal Oxygen Consumption (VO2
   Determined by the ability of the body to
    uptake, distribute, and utilize oxygen.
   Determined partly on genetics, and
    partly on fitness status.
   Considered the best overall measure of
    the capacity of the CR system.
Energy systems in combination
 Your body typically uses all three
  energy systems when you exercise.
   The intensity and duration of the activity
    will determine which system
   Fitness status
   Previous diet
 See Figure 9.8 p. 304
 Fat and carbohydrate are the primary fuels
  for endurance exercise.
 See Table 9.9, p. 304 for substrate stores.
 How does one choose foods that will
  best fuel their body?
   From an energy perspective
   From a health/wellness/disease
    prevention perspective????
Dietary Guidelines for Health and
Disease Prevention
 Dietary Guidelines for Americans
   Aim for Fitness
   Build a healthy base
   Choose sensibly
Aim for Fitness
 1. Aim for a healthy weight
   As previously discussed, 55% of adults
    and 22% of children and adolescents are
    overweight and obese in the US today.
   OW and OB are linked with HTN, heart
    disease, stroke, diabetes, certain
    cancers, arthritis, and other types of
   Calories in—Calories out
Aim for Fitness
 2. Be physically active every day.
   More than 60% of American adults do not
    engage in recommended amounts of physical
   25% of American adults are not active at all.
   Only about 15% of American adults engage in
    regular, daily, moderate physical activity for at
    least 30 minutes per day.
   Refer to Table 1.1, p. 7 in text.
Build a Healthy Base
 3. Let
  be your
Build a Healthy Base
 The FGP was developed by the USDA
  to help consumers translate nutrient
  recommendations into a plan for
  healthy eating.
 Range of serving sizes from six food
   Total number of servings needed
    depends on caloric needs.
     1600-2800 calories/day
     See Box 9.3, p. 289.
Build a Healthy Base
 Within each food group, foods vary in the
  amount of nutrients and calories they
 Not all foods are created equal!
 All foods can fit!
 Best choices emphasize nutrient density—
  those that are high in nutrients relative to
  the amount of calories they contain.
   E.g.: A slice of whole grain bread compared to a
Build a Healthy Base
Build a Healthy Base
Build a Healthy Base
Dietary practices of children and adolescents.

Proportion of persons aged 2 & older who:                     Consume:     2010
                                                               Current    Target
                                                               Baseline    (%)
three or more daily servings of vegetables, with 33% from
dark green & yellow veggies                                   3         50
six or more daily servings of grain products, three or more
from whole grain                                       7         50
two or more daily servings of fruit   
                                                                28         75
less than 30% of calories from fat    
                                                                33         75
less than 10% of calories from saturated fat   
                                                                36         75
meet dietary recommendation for calcium
                                                                46         75
Build a Healthy Base
 4. Choose a variety of Grains daily,
  especially whole grains.
   Most foods chosen each day should come from
    this segment of the pyramid.
   Choosing more whole-grain products will
    increase consumption of total % carbohydrates
    and fiber, and will decrease fat consumption.
   Choose unrefined, whole grains over refined,
    processed foods.
   Recommendation is for AT LEAST 55% of total
    calories to come from carbohydrates, with no
    more than 10-15% of these to come from
    simple carbohydrate sources.
Simple Carbohydrates
 Contain only one or two sugar units in each
 One-unit molecule= MONOSACCHARIDE
   glucose, fructose, and galactose
 Two unit molecule = DISACCHARIDE.
   These include:
     sucrose (table sugar) fructose + glucose
     maltose (malt sugar) glucose + glucose
     lactose (milk sugar) glucose + galactose.
 Simple carbs provide much of the
  sweetness in foods.
Complex Carbohydrates
   Starches and most types of dietary fiber.
       SOLUBLE: slows the absorption of glucose, binds cholesterol, which reduces serum
        cholesterol and CAD risk.
       INSOLUBLE: binds water, making feces bulkier and softer
            Both kinds of fiber contribute to disease prevention.
            A diet high in soluble fiber can help people manage diabetes and high chol. levels.
            A diet high in insoluble fiber can help prevent constipation, hemorrhoids,
             diverticulitis and colon and rectal cancers
            Some research suggests it may also reverse pre-CA changes.
   Consist of chains of many glucose molecules.
   All plant foods contain some dietary fiber.
       Those particularly rich in fiber include fruits, legumes, oats (oat bran), barley, and
       Wheat (bran) cereals, grains, and veggies are good sources of insoluable fiber
       See Table 9.3, p. 292
       Recommendation for daily fiber intake is 20-35 grams. Current intake is about 14
Refined vs. Unrefined
 The processing of packaged foods can
  remove fiber.
 Refined carbohydrates retain all the
  calories, but are lower in fiber, vitamins,
  and minerals.
 Unrefined carbohydrates take longer to
  chew and digest, and enter the blood more
   These have many health benefits.
     Feel fuller longer, more anti-oxidant vitamins
      and phytochemicals, and decreased risk of
Build a Healthy Base
 5. Choose a variety of fruits and
  vegetables daily.
   Fruits and veges are complex foods
    containing more than 100 beneficial
    vitamins, minerals, fiber, and other
    substances such as phytochemicals.
Build a Healthy Base
 Phytochemicals and
   Much new research
    being done on these.
   Are said to aid in the
    preservation of the
    body’s healthy cells.
   Free-radicals damage
    cell membranes and
    cause gene
Build a Healthy Base
 A Free Radical is a chemically unstable molecule that is
  missing an electron. It will react with any molecule it
  encounters from which it can take an electron. (For
  example fats, proteins and DNA. This damages cell
  membranes and mutates genes.
 Therefore, they have been implicated in aging, cancer,
  cardiovascular disease, and degenerative diseases such
  as arthritis.
 Environmental factors such as cigarette smoking,
  exhaust fumes, radiation, excessive sun exposure,
  certain drugs, and stress can increase free radical
 Antioxidants react with free radicals and donate lost
  electrons. They help by blocking the formation and
  action of free radicals and repair the damage they cause.
      Vitamin C, Vitamin A (beta-carotene), Vitamin E and selenium
       are a few examples of antioxidants.
Build a Healthy Base
 Phytochemicals
   Anti-oxidants are a particular type of
    phytochemical which is a substance
    found in plant foods that may help
    prevent chronic diseases.
   Examples of phytochemicals include
    sulforaphane (found in cruciferous
    veges), allyl sulfides, and isoflavones.
   See handout
Build a Healthy Base
 6. Keep food safe to eat.
   Food-borne illness is caused by eating
    foods that contain harmful bacteria,
    toxins, parasites, viruses, or chemical
   S/S of having eaten unsafe food may
    appear within half an hour, or may not
    develop for up to 3 weeks.
   Refer to p. 294 for steps to follow to
    keep food safe.
Choose Sensibly
 7. Choose a diet that is low in saturated fat
  and cholesterol and moderate in total fat.
   Most fats in food are in the form of triglycerides.
     Triglycerides are composed of a glycerine
      molecule (an alcohol) plus three fatty acid
     Fatty acids are made up of a chain of carbon
      atoms with oxygen attached at the end and
      hydrogen atoms attached along the length of
      the chain.
     Fatty acids differ in the length of their carbon
      atom chains.
Choose Sensibly
Choose Sensibly
  Cholesterol
    Is a type of fat (sterol) found in animal
     products only.
    It is manufactured by the body in the liver.
    High levels of cholesterol are linked to
     coronary artery disease.
    RDA for cholesterol is less than 300
Choose Sensibly
 Fatty acids also differ by their degree of saturation.
 Fats are classified as saturated or unsaturated
  depending on the amount of double bonds located
  between the carbon atoms.
   If no double bonds exist between carbons, a fat is
     classified as ―Saturated‖.
   Fats are unsaturated depending on the amount of
     double bonds between C atoms.
       FA’s with one double bond are called
       FA’s with two or more double bonds are called
Choose Sensibly
 Main sources of saturated fats in the
  American diet are: hamburger,
  steak, roast, poultry skin, ice cream,
  and many baked products, cheese,
  coconut and palm oil, Crisco and
 These are solid at room temperature.
Choose Sensibly
 Foods that are classified as mono or poly
  unsaturated typically come from plant
   They are liquid at room temperature. This is
    because there is not as many hydrogen bonds to
    the carbons.
 Main sources include oils, except palm and
  coconut oil.
 Mono’s=olive, canola, safflower and peanut
 Poly’s=corn, soybean and cottonseed
Choose Sensibly
Choose Sensibly
   The process of adding hydrogen to an oil to improve the
    texture of foods and increase shelf life. Also helps the fat
    be more capable of withstanding high temperatures for
   Turns a liquid oil into a solid.
       Turns the double bonds in unsaturated fats to single bonds,
        thereby increasing the degree of saturation and producing a
        more solid fat from a liquid oil.
   Margarine...
   The process of hydrogenation produces fatty acids that are
    not quite the same as a saturated fat, and are referred to
    as trans-fatty acids.
       Read on nutrition labels as hydrogenated or partially-
        hydrogenated vegetable oils.
       Leads to health risk due to increase in cholesterol level.
       Refer to Figure 9.4, p. 295 for fatty acid structure and food
Chemical Structure of Fatty Acids
Choose Sensibly
Choose Sensibly
 Omega-3 Fatty Acids
   Is a form of polyunsaturated fat.
   Found in many kinds of fish.
   May play a role in CAD prevention.
   Has been found to reduce the tendency of the blood
    to clot, to decrease inflammatory responses, helps
    heart to beat in a steady rhythm, and to increase
    HDL levels in women.
   Recommendations is to have two or more servings
       Examples: salmon, tuna, trout, mackerel, herring,
        sardines, and anchovies.
       Plant sources include dark green leafy veges, walnuts,
        and flax seeds.
Choosing Sensibly
 Calculating Fat %, Reading Food Labels
   Find the food nutrition label.
   Look at the total number of calories and fat
    grams in one serving.
   Multiply the number of fat grams by 9.
   Divide that number by the number of total
   Result is percent of calories that product has
    that come from a fat.
   Refer to Figure 9.3, p. 293.
Example: Ho-Ho’s
 Serving size = 2 rolls.
 Calories per serving = 290.
 Total Fat per serving = 15 grams
 Saturated fat = 7 grams.
 Calculate: 15 X 9 = 135, thus 135 calories
  are fat calories.
 135 / 290 = 0.465 or 47%.
 SO, 47% of the calories in a HO-HO is from
  fat, and 22% is from Sat. fat. YUCK!!!
Choose Sensibly
 High saturated and trans-fat in the diet increases level
  of serum cholesterol and LDL, and lowers HDL.
   High LDL leads to increased risk of CAD.
 Consumption of unsaturated fats may lead to a
  decrease in total serum cholesterol
   Mono-unsaturated fats may lower total cholesterol
      and LDL, yet have no effect or may raise HDL
   Poly-unsaturated fats may also lower total cholesterol
      and LDL, but tend to also lower HDL
 Diet high in fat may also lead to cancer and weight
  management problems.
Choose Sensibly
 To lower trans fats, decrease intake of:
   Deep-fat fried foods and baked goods made with
    hydrogenated vegetable oils.
 Choose:
   Liquid oils rather than margarine or shortening
    for cooking, and flavor tub or squeeze
    margarines or those labeled low-trans or trans-
    free over standard stick margarines.
     Remember, the softer or more liquid the fat
       is, the less saturated and trans fat it is
       likely to contain.
Choose Sensibly:
Reducing the fat in your diet
   See list on p. 296, text.
   Be moderate in your intake of fast foods, commercially
    prepared baked goods and desserts, deep-fried foods, meat,
    poultry, nuts and seeds, and regular dairy products.
   Season vegetables, seafood, and meats with herbs and spices
    rather than with creamy sauces, butter, or margarine.
   Try non-fat mayonnaise and fat-free salad dressings.
   Steam, boil, bake, or microwave vegetables.
   Roast, bake, or broil meats, poultry, or fish so that fat drips
    away as it cooks.
   Use non-stick cookware so added fat is not necessary.
   Make gravies with de-fatted broth.
   Substitute egg whites or egg beaters for whole eggs.
   Substitute liquid butter buds, applesauce or non-fat yogurt for
    butter or margarine in baking.
Choose Sensibly: Fat Intake
   Humans only need a single tablespoon of vegetable oil per
    day (15 grams) to get their essential FA.
       Linoleic and alpha-linolenic
       These are polyunsaturated fats.
   The average American consumes about 32-38% of their
    calories from fat (75 grams or 5 tbls.)
     Over recent years, the percentage of calories from fat
        has decreased, but, because of increased caloric
        consumption over these past recent years, we are
        actually consuming more total grams of fat.
   Recommendations: No more than 30% of calories from fat,
    and no more than 7-10% from saturated fat sources, up to
    10% from polyunsaturated sources, and up to 20% from
    monounsaturated sources.
Food For Thought…..
 The text states that the goal is to end
  up with fewer than 30% of your total
  day’s calories to come from fat.
 I wonder if it should not be to try to
  keep the fat in each individual food
  from contributing more than 30% of
 Also, is 30% too high????? I wonder.
Choose Sensibly
 8. Choose beverages and foods to
  moderate your intake of sugars.
   As discussed previously, sugars are classified as
    simple carbohydrates, whereas starch is defined
    as a complex carbohydrate.
   Sugars and starches occur naturally in many
    foods—including milk, fruits, some vegetables,
    bread, cereals, and grains.
     These foods, however, provide many
       important nutrients.
     On the other hand, so-called added sugars-
       supply added calories, but few nutrients.
   Foods rich in added sugars include things like
    soft drinks and desserts.
Choose Sensibly
 How       Carbonated beverages         8-10 tsp
  much      yogurt                       7   tsp
  sugar     1 cup canned corn            3   tsp
  is        1 tablespoon ketchup         1   tsp
            Glazed donut                 6   tsp
  this???   1 choc. Éclair or piece of
            angel food cake              7 tsp
            2 oz. chocolate candy        8 tsp
            Iced chocolate cake or
            berry pie                    10 tsp
            4 oz hard candy              20 tsp
Choose Sensibly
 A sugar by any other name…
   Read the label to locate hidden sugars in the
    foods you consume.
   Sugars are listed by many different names,
    including brown sugar, corn sweetener, corn
    syrup, fructose, fruit juice concentrate, glucose
    or dextrose, high-fructose corn syrup, honey,
    lactose, maltose, molasses, raw sugar, table
    sugar, or sucrose, and syrup.
     If one of these appears near the top of the
       ingredients list, the food is probably high in
       added sugars.
 Choose Sensibly
 Recommendations:
   The FGP places foods high in added sugars at the top
    of the pyramid.
   Average American intake of added sugars: males-22
    tsps., females, 16 tsps.
     This does not include naturally occuring sugars
       found in foods such as milk and fruits.
   The USDA recommendation:
     1600 calories/day = no more than 6 tsp/day
     2200 calories/day = no more than 12 tsp/day
     2800 calories/day = no more than 18 tsp/day
Choose Sensibly
 Rationale:
   Sugars and starches can both promote
    tooth decay.
   Sugars increase serum triglyceride
   Added calories for little nutrient density.
 Choose Sensibly
 9. Choose and prepare foods with less
   The human body requires 500 mg Na/day.
   Average American consumes about 4,000-
    6,000 mg/day.
   High Na intake associated with HTN.
   USDA recommendation: no more than 2,400
    mg/day or about 1 tsp. NaCl/day.
   Refer to Table 9.4, p. 297 text for sources
    of salt.
Choose Sensibly
 Tips for reducing salt intake:
   Read food labels.
   Choose more fresh fruits and veges.
   Choose fresh or frozen fish, shellfish, poultry,
    and meat. They are lower in salt than most
    canned and processed forms of meats.
   Reduce salt use during cooking. Substitute
    herbs and low-Na seasonings.
   Avoid the salt shaker, and limit use of
    condiments such as soy sauce, ketchup,
    mustard, pickles, and olives.
   Limit intake of foods with visible salt on them,
    such as snack chips, salted nuts, cracker, etc.
Choose Sensibly
 10. If you drink alcoholic beverages,
  do so in moderation.
   Alcohol supplies calories with very little
    nutrition. (7 calories/gm).
   Alcohol is linked with many health
    problems, birth defects, accidents,
    violent crimes, and addiction.
     See list on p. 298 for USDA identified
      groups that should abstain from alcohol.
Choose Sensibly
 Moderate intake means……
   No more than two drinks a day for men, and one
    drink a day for women.
   One serving of alcohol, commonly called a
    ―drink‖ delivers 0.5 ounces of pure alcohol.
     12 oz regular beer (150 calories)
     5 oz wine (100 calories)
     1.5 oz of 80-proof distilled spirits (100 cals)
     10 oz of wine cooler (140 calories)
   See Table 9.5 for BAC and symptoms.
10 Cardinal Sports-Nutrition Principles
that are Applicable to the Athlete
 1.  Prudent diet is the cornerstone
 2.  Increase total energy intake
 3.  Keep the dietary carbohydrate intake high (55-70%)
     during training
 4. Drink large amounts of fluid during training and the
 5. Keep a close watch on possible iron deficiency
 6. Vitamin and mineral supplements are not needed
 7. Protein supplements do not benefit the athlete
 8. Rest and emphasize carbohydrates before long
     endurance events
 9. Use of ergogenic aids is unethical
 10. Fat loading is not recommended for enhanced
     performance or health
Prudent diet is the cornerstone
 For all Americans, physically active or
  not, the ―prudent diet‖ is the
 The ―prudent diet‖ adheres to
  recommendations from the National
  Research Council, and the USDA’s
  Dietary Guidelines for Americans
 RDA’s provided in text on pages 284-
Prudent diet is the cornerstone
   Dietary practices of athletes
       Athletes who purposely keep their weight below natural weight for competition tend
        to have reported caloric intakes that fall way below calculated energy expenditure.
       Athletes in sports that emphasize leanness (wrestlers, gymnasts, body builders,
        runners, and ballet dancers) are exceptionally preoccupied with weight and tend to
        use unhealthy methods for weight control, tend toward eating disorders and
        demonstrate poor nutrition practices.
   Protein intake in athletes ranges form 10 – 36% of total calories. Athletes
    are not much different than the non-athletic population, who also tends to
    consume nearly double the RDA for protein.
   Fat intake averages 36% of energy intake in athletes. Power and strength
    athletes tended to have higher fat intakes than endurance athletes, and this
    is often associated with the higher protein intake.
   Carbohydrate provides about 46% of energy consumed by athletes. Tri-
    athletes tended to have higher carbohydrate intake than the other athletes.
   Vitamin and mineral intakes tended to be higher than the RDA, because the
    athletes ate more food than inactive people. There is also widespread use of
    supplements in athletes. However, sports emphasizing leanness were found
    to consume insufficient quantities of vitamins and minerals.
   In general, the quality of the athletes diet is somewhat similar to that of the
    general population.
Increase total energy intake
 If a person is of normal body weight, and
  they exercise regularly, that person’s
  energy consumption will need to be higher
  than that of the average sedentary
  individual to maintain body weight.
 The amount and intensity of training and
  body size are the chief determinants of the
  energy requirements of the athlete.
 See Table 9.7, p. 301
Keep the dietary carbohydrate intake
   high (55-70%) during training
    There are several basic principles regarding the relationship between exercise and
     dietary carbohydrate and muscle glycogen.
        Body glycogen stores play an important role in hard exercise (70-85% of VO2 max) that is
         either prolonged and continuous or of an extended intermittent mixed anaerobic-aerobic nature.
        There are limited CHO stores in the body, and the body adapts in various ways to maximize its
         use of these stores.
        Exhaustion during prolonged, hard exercise is tied to low muscle glycogen levels.
        When muscle and liver glycogen stores are low, a high work output cannot be maintained.
         ―Hitting the Wall‖
        During the first hour of hard exercise, most CHO and fat come from within the muscle. As
         exercise continues beyond one hour, more demand is placed upon adipose tissue fat fuel
         sources and blood glucose as muscle glycogen levels begin to be depleted. The longer the
         exercise, the greater the need for glucose from the liver.
        During training, muscle glycogen stores undergo rapid day-to-day fluctuation.
        Rapid restoration of muscle glycogen stores is essential to those athletes that compete or train
         repeatedly on same or consecutive days.
    Glycemic index—which foods to choose pre, during and post event/training. See Box
     9.5, p. 309.
    Recommendation: athletes in heavy training should consume a diet of close to 70%
     CHO, or about 525 grams per 3000 calories). This will restore muscle glycogen within
     24 hours, enabling the athlete to continue heavy training. This is especially important
     after race events and long, intense training bouts.
         See table 9.10 for listing of high CHO foods.
    Drink large amounts of fluid during
    training and the event
    As little as a 2% drop in body weight caused by water loss (primarily from sweat) can reduce
     exercise capacity.
    If you are thirsty, you are already dehydrated.
    Recommendation: Drink 2 cups of water immediately before exercise, 1 cup every 15
     minutes during exercise, and then 2 more cups after the session.
    If exercising longer than one hour, then consider carbohydrate and sodium drinks.
    Loss of body water from sweating beyond 2% of body weight will significantly impair
     endurance capacity, through elevation of body temperature and decreased cardiac output.
     When sweat output exceeds water intake, both intracellular and extra-cellular water levels
     fall, and plasma volume decreases. This results in an increase in body temperature, a
     decrease in the ability of the heart to pump blood, and a decrease in endurance performance.
        Intracellular fluid accounts for 67%, Interstitial (between cells) fluid accounts for 27% and plasma
         volume accounts for 6% of an average 70 kg individual with 42 liters of body water. (60% of body
    Acclimatization process occurs as people train in the heat. The individual will have a higher
     plasma volume and sweat glands will produce more sweat earlier in the exercise session, with
     less loss of sodium. Body temp and HR do not rise as strongly in those who are acclimatized.
    When the body loses water during prolonged exercise, and it is not replenished, there is a
     gradual decrease in heart stroke volume, and a corresponding increase in heart rate.
    Box 9.6, p. 316- ACSM position stand on fluid replacement.
    Should electrolytes and carbohydrates be used during exercise? When exercise exceeds one
     hour, the exercisers fluid, electrolyte, and carbohydrate requirements can be met
     simultaneously by ingesting 600-1200 ml/hour of a solution containing 4-8% CHO and 0.5-
     0.7 grams of sodium per liter.
Keep a close watch on possible iron
 Some athletes, especially females, may be
  prone to iron deficiency.
 Recommendation is to not routinely take
  iron supplements without medical
  supervision, but to increase iron
  consumption by eating foods high in iron.
 Heme-Fe and non-heme Fe.
     Vitamin C
 See table 9.15, p. 322 for foods with
  various iron contents.
    Vitamin and mineral supplements
    are not needed
    Most studies show that the intake of major vitamins and minerals by people who
     exercise is above recommended levels.
        The increase in food eaten by exercisers provides the extra vitamins and minerals,
         particularly if the diet consists of a high-carbohydrate, moderate protein, low-fat menu.
    Even though many coaches and fitness journals urge supplementation to boost
     or maximize performance, the ACSM, the ADA, and Dietitians of Canada have
     made a statement that no vitamin or mineral supplements are required if an
     athlete is consuming adequate energy from a variety of foods.
        The AMA, the ADA, the American institute of nutrition, the food and nutrition board, and
         the national council against health fraud, have submitted formal statements to the
         effect that there are no demonstrated benefits of self-supplementation beyond the RDA,
         except in special cases. submitted a formal statement to the effect that there are no
         demonstrated benefits of self-supplementation beyond the RDA, except in special cases.
    Recommendation: The best nutritional strategy for promotion optimal health
     and reducing the risk of chronic disease is to obtain adequate nutrients from a
     wide variety of foods.
    High intake of vitamins and minerals even could be problematic, especially with
     the fat soluble vitamins A,D,E, and K. Furthermore, excess of one nutrient can
     cause a deficiency in another nutrient.
        Research shows that between 50 and 80% of elite athletes use vitamin and mineral
         supplements on a regular basis.
Protein supplements do not benefit
the athlete
   Many people who exercise, especially weight lifters, feel that consumption of
    high-protein foods and protein supplements is necessary to build muscle
       The average sedentary person has been advised to consume 0.8 gram of protein per
        kilogram of body weight. Research is showing that highly active people may need
        50-125% more than this because 5-15% of the energy required for long endurance
        exercise or weight lifting comes from protein, and extra protein is needed for muscle
        protein synthesis. However, most experts feel that the traditional food supply
        provides all of the protein needed, even for the athletes during active muscle-building
        phases—supplements are not needed.
   The American Dietetic Association has advised that endurance athletes take in
    1.2-1.4 g/kg protein daily. However, most endurance athletes are already
    getting this much protein and do not need to supplement their diets with
    protein powder or concern themselves with eating high-protein foods.
   Most strength and power athletes can enhance muscle development when
    dietary protein intake ranges between 1.6 and 1.7 g/kg. There is no evidence
    that very high protein intakes (>2g/kg/day) are either necessary or beneficial.
   There is little scientific evidence that amino acid supplementation enhances
    the physiological responses to strength training when adequate diets are
   See Table 9.17 for a list of the protein content of common foods.
   Refer to Box 9.7, p. 328 for special issues for Vegetarians.
    Rest and emphasize carbohydrates
    before long endurance events
    When an event lasts longer than 60-90 minutes, it is
     recommended to taper off the exercise gradually during the
     week before the event, while consuming more than 70% CHO
     during the 3 days before the event. If the event is less than 60
     minutes, carbohydrate loading is not necessary.
    See page 329 for CHO loading.
    For the pre-event meal, most sports-nutrition experts advise
     one or two glasses of water, followed within 20-30 minutes by
     a light (500-800 kcal) meal of rapidly digestible, low-fiber
     starch (cream of wheat hot cereal, white bread, bagels, pasta,
     refined cereals, low glycemic index foods). The food should be
     consumed 3-5 hours before the event, so the stomach will be
     empty at the time of competition to avoid abdominal fullness or
    The use of proteins, fats, known gas-forming foods, high-fiber
     foods, and foods known to act as laxatives is not
Use of ergogenic aids is unethical
 Five categories of ergogenic aids:
     Nutritional aids
     Pharmacological aids
     Physiological aids
     Psychological aids
     Mechanical aids
 See Table 9.18, p. 332 for products,
  claims, and fact on their ergogenic
Fat loading is not recommended for
enhanced performance or health
  Athletes have no guarantee of protection from heart
   disease unless they continue prudent habits of
   exercise and diet after their days of competition are
   Even during heavy training, a diet high in saturated
       fats can raise serum cholesterol to high levels.
   Regular endurance exercise will not fully negate bad
       nutritional habits.
 Nearly all studies have shown that high-fat diets
   (about 70% of total energy) for several days prior to
   endurance exercise significantly decrease body
   carbohydrate stores, reducing endurance time
   dramatically. Although the relative contribution of fat
   is increased, performance is impaired due to low
   muscle glycogen.
 Refer to page 342 for a summary of
  the ten Principles outlined in the text.

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