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Chapter 10 Nutrients, Physical Activity, and the Bodys Responses


Nutrition and physical activity are interactive ... swimming, cross-country skiing, rowing, fast walking, jogging, fast bicycling, ... – PowerPoint PPT presentation

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Title: Chapter 10 Nutrients, Physical Activity, and the Bodys Responses

Chapter 10 Nutrients, Physical Activity, and the
Bodys Responses
  • Nutrition and physical activity are interactive
  • As you improve your physical fitness, you not
    only feel better and stronger, but you look

  • Fitness depends on a minimum amount of
  • Physical activity
  • Exercise
  • People who regularly engage in just moderate
    physical activity live longer (on average) than
    those who are inactive
  • 25 of adults in the U.S. are inactive

Benefits of Fitness
  • More restful sleep
  • Better nutritional health
  • Physical activity expends energy and thus allows
    people to eat more food
  • Improved body composition
  • limits body fat and increases or maintains lean
  • Improved bone density
  • builds bone strength and protects against
  • Lower risk of some kinds of cancer
  • Lifelong physical activity may help to protect
    against colon cancer, breast cancer

Benefits of Fitness
  • Lower risks of type 2 diabetes
  • Reduced risk of gallbladder disease
  • Stronger circulation and lung function
  • Lower risks of cardiovascular disease
  • Physical activity lowers BP, slows resting pulse
  • Lower incidence and severity of anxiety and
  • Stronger self-image
  • Longer life and better quality of life

Benefits of Fitness
  • The American College of Sports medicine (ACSM)
  • Specifies that people need to spend a minimum of
    30 minutes in some sort of physical activity on
    most days of the week
  • The Dietary Guidelines for Americans, 2005
  • The DRI committee recommends at least 60 minutes
    of moderately intense activity

The Essentials of Fitness
  • A variety of physical activities produces the
    best overall fitness
  • Stretching enhances flexibility, the ability of
    the joints to move through a full range of motion
    and the ability to bend and recover without
  • Weight training develops muscle strength and
    endurance, the ability of muscles to work against
  • Aerobic activity improves cardiorespiratory
    endurance-(oxygen- strengthens the heart and
    lungs by requiring them to work harder than
    normal to deliver oxygen to the tissues)

What is Weight Training?
  • The use of free weights or weight machines can
    provide resistance for developing muscle strength
    and endurance
  • A persons own body weight may be used to provide
    resistance as when a person does push-ups,
    pull-ups, or sit-ups

The Essentials of Fitness
  • Benefits of weight training
  • Prevent and manage several chronic
    diseases/cardiovascular disease
  • Promotes strong muscles in the back and
    abdomen--Can improve posture and reduce the risk
    of back injury
  • Prevents the decline in physical mobility as we
  • Can maintain bone mass/bone density
  • Can emphasize either muscle strength or muscle
  • To emphasize muscle strength
  • Combine high resistance with a low number of
  • To emphasize muscle endurance
  • Combine less resistance with more repetitions
  • Enhances performance in other sports
  • Swimmers can develop a more efficient
  • Tennis players can develop a more powerful

The Essentials of Fitness
  • How Does Cardiorespiratory Training Benefit the
  • It determines how long you can remain active with
    an elevated heart rate
  • It is the ability of the heart and lungs to
    sustain a given physical demand
  • It is aerobic.
  • Examples of activities---swimming,
    cross-country skiing, rowing, fast walking,
    jogging, fast bicycling, soccer, hockey,
    basketball, in-line skating, lacrosse, rugby

The Essentials of Fitness
  • As cardiorespiratory endurance improves, the
    body delivers oxygen more efficiently
  • The total blood volume and the number of red
    blood cells increase
  • The heart becomes stronger and larger
  • The heart pumps more oxygen --Cardiac output
  • The heart pumps more blood per beat-- Stroke
    volume increases
  • Fewer beats pulse rate falls
  • Breathing becomes more efficient

The Essentials of Fitness
The Active Bodys Use of Fuels
  • Fuels/Energy that support body activity are
  • Glucose--From carbohydrate
  • Fatty acids--From fat
  • To a small extent, amino acids--from protein
  • The body uses different mixtures of fuels
    depending on the intensity and duration of its
    activities and prior training

The Active Bodys Use of Fuels
  • During rest
  • The body gets a little more than half of its
    energy from fatty acids
  • Most of the rest from glucose
  • A little from amino acids
  • During physical activity
  • The body adjusts its fuel mix to use the stored
    glucose of muscle glycogen
  • In the early minutes of activity, glycogen
    provides the majority of energy the muscles use
    to go into action
  • As the activity continues epinephine signals the
    liver and fat cells to release glucose and fatty

Glucose Use and Storage
  • As activity continues
  • Glucose from the livers stored glycogen and
    dietary glucose absorbed from the digestive tract
    also become important sources of fuel for muscle
  • The body constantly uses and replenishes its
  • The more carbohydrate a person eats
  • The more glycogen muscles store (there is a limit
    to less than 2,000 calories of energy
  • Fat stores can usually provide more than 70,000
    calories and fuel hours of activity without
    running out

Glucose Use and Storage
  • A classic study compared three diets used by
    three groups of runners, each on a different diet
  • one groups ate a normal mixed diet-55 CHO
  • a second group ate a high-carbohydrate diet-83
  • the third group ate a high-fat diet94 fat
  • The high-carbohydrate diet enables the athletes
    to work longer before exhaustion

Activity Intensity, Glucose Use, and Glycogen
  • Anaerobic Use of Glucose
  • Anaerobic
  • Not requiring oxygen
  • Anaerobic activity may require strength but does
    not work the heart and lungs very hard for a
    sustained period
  • The muscles begin drawing on their limited
    glycogen supply
  • Glucose can yield energy quickly
  • Weight lifting, sprint

Activity Intensity, Glucose Use, and Glycogen
  • Moderate physical activity uses glycogen
    slowly-Aerobic activity (easy jogging)
  • The individual breathes easily and the heart
    beats at a faster pace than at rest
  • During aerobic metabolism muscles get their
    energy from both glucose and fatty acids
  • Moderate activity conserves glycogen stores

Activity Intensity, Glucose Use, and Glycogen
  • During intense activity, the anaerobic breakdown
    of glucose produces a by product called lactic
  • Liver enzymes can convert the lactic acid back
    into glucose
  • The glucose return to the muscles to fuel
    additional activity

Activity Intensity, Glucose Use, and Glycogen
  • At low intensities, lactic acid is cleared from
    the blood by the liver
  • At higher intensities, lactic acid accumulates
  • When the rate of lactic acid production exceeds
    the rate of clearance, intense activity can be
    maintained for only one to three minutes

Activity Duration Affects Glucose Use
  • Glucose use depends on the duration and intensity
    of the activity
  • In the first 10 minutes
  • muscles rely almost entirely on their own stores
    of glycogen
  • Within the first 20 minutes of moderate activity
  • About one-fifth of their available glycogen is
    used up
  • Blood glucose also decreases and is used by the

Activity Duration Affects Glucose Use
  • After 20 minutes less glucose and more fat is
    used for fuel
  • If the activity goes on long enough and at a high
    enough intensity glycogen depletion occurs after
    about two hours
  • When hypoglycemia and glycogen depletion occur
    activity stops

Activity Duration Affects Glucose Use
  • Maintaining Blood Glucose for Activity
  • Eat a high-carbohydrate diet regularly
  • Take glucose (usually in sports drinks)
    periodically during endurance activities
  • Eat carbohydrate-rich foods after performance
  • Train the muscles to maximize glycogen
    stores--Carbohydrate loading

Activity Duration Affects Glucose Use
  • Carbohydrate Loading
  • A regimen of moderate exercise, followed by
    eating a high-carbohydrate diet
  • It enables muscles to temporarily store double
    the glycogen beyond their normal capacity
  • It can benefit athletes who must keep going 90
    minutes or longer

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Activity Duration Affects Glucose Use
  • Glucose After Activity
  • High-carbohydrate foods after physical activity
    replaces glycogen stores
  • Eating a high-carbohydrate meal within 2 hours
    after physical activity accelerates the rate of
    glycogen storage by 300
  • This is important to athletes who train hard more
    than one time a day
  • High-carbohydrate energy drinks can be used to
    restore muscle glycogen after exercise or as a
    pregame beverage

Should Athletes Eat More Fat?
  • When endurance athletes fat load by consuming
    high-fat, low-carbohydrate diets for 1 to 3 days
  • performance is impaired because their small
    glycogen stores are depleted quickly
  • Endurance athletes who fat load for more than a
  • Adapt to relying on more fat to fuel activity
  • Performance benefits have not been consistently

Should Athletes Eat More Fat?
  • High-fat diets carry risks of heart disease
  • Physical activity offers some protection against
    CV disease however athletes can suffer heart
    attacks and strokes
  • A diet that restricts fat is not recommended
  • Endurance athletes should consume 20-30 of
    their energy from fat
  • As fuel for activity, body fat stores are more
    important than fat in the diet
  • Fat stores can fuel hours of activity without
    running out, even for marathoners

Should Athletes Eat More Fat?
  • Early in activity muscles draw on fatty acids
    from two sources
  • Fats stored within the working muscles
  • Fats under the skin
  • Areas with the most fat to spare donate the
    greatest amounts of fatty acids to the blood

Should Athletes Eat More Fat?
  • Intensity and Duration Affect Fat Use
  • The intensity of physical activity affects the
    percentage of energy contributed by fat
  • Fat can be broken down for energy only by aerobic
  • When the intensity of activity becomes so great
    that energy demands surpass the ability to
    provide energy aerobically, the body cannot burn
    more fat instead, it burns more glucose

Should Athletes Eat More Fat?
  • The duration of activity also matters to fat use
  • At the start of activity, the blood fatty acid
    concentration falls
  • But a few minutes into an activity norepinephrine
    signals fat cells to break apart their stored
    triglycerides and to liberate fatty acids into
    the blood
  • After about 20 minutes of activity, the blood
    fatty acid concentration rises above normal
    resting concentrations
  • It is during this phase that fat cells begin to
    shrink in size

Should Eat More Fat?
  • Degree of Training Affects Fat Use
  • Training stimulates muscles to develop more
    fat-burning enzymes
  • Aerobically trained muscles burn fat more readily
    than untrained muscles
  • With aerobic training, the heart and lungs become
    stronger and better able to deliver oxygen to the
    muscles during high-intensity activities

Can Physical Training Speed Up an Athletes
  • Athletes in training expend huge amounts of
    energy each day while practicing
  • Research suggests that the athlete uses more
    energy at rest than a sedentary person or a
    casual exerciser
  • Intense endurance activity can increase BMR for
    anywhere from 5 minutes to hours

Using Protein and Amino Acids
  • Athletes use dietary protein to build and
    maintain muscle and other lean tissue structure
  • The body handles protein differently during
    activity than during rest
  • During rest muscles speed up their rate of
    protein synthesis to remodel muscle

Using Protein and Amino Acids
  • Protein for Fuel
  • Athletes retain more protein, and use a little
    more protein as fuel
  • Studies of nitrogen balance show that the body
    speeds up its use of amino acids for energy
    during physical activity
  • Protein contributes about 10 of the total fuel
  • A carbohydrate-rich diet spares excess protein
    from being used as fuel
  • Some amino acids can be converted into glucose
    when needed
  • If the diet is low in carbohydrate, much more
    protein will be used in place of glucose

Using Protein and Amino Acids
  • Intensity and Duration Affect Protein Use
  • Endurance athletes training more than an hour a
    day may deplete their glycogen stores by the end
    of their training period and become more
    dependent on body protein for energy

How Much Protein Should an Athlete Consume
  • The protein needs of endurance and strength
    athletes are higher than those of sedentary
  • Athletes in training should take care of protein
    and carbohydrate needs
  • Otherwise, they will use protein as fuel rather
    than to retain muscle
  • The DRI committee does not recommend
    greater-than-normal protein intakes for athletes
  • Other authorities do
  • The American Dietetic Association and the
    Dietitians of Canada recommend protein intakes
    higher than the 0.8 gram of protein per kilogram
    of body weight recommended for sedentary people

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Vitamin and Minerals - Keys to Performance
  • Many vitamins (Bs) and minerals assist in
    releasing energy from fuels and transporting
  • Vitamin C is needed for the formation of the
    protein collagen
  • The foundation material of bones and the
    cartilage that forms the linings of joints and
    other connective tissues
  • Folate and vitamin B12 help build red blood cells
  • Calcium and magnesium help make muscles contract

Do Nutrient Supplements Benefit Athletic
  • Nutrient supplements do not enhance the
    performance of well-nourished athletes or active
  • Deficiencies of vitamins and minerals adversely
    effect performance
  • Taking vitamin or mineral supplements just before
    competition will not enhance performance

Do Nutrient Supplements Benefit Athletic
  • Athletes who lose weight making weight to meet
    low body-weight requirements may consume so
    little food that they fail to obtain all the
    nutrients they need
  • A daily multivitamin-mineral tablet that provides
    the DRI recommendations can be beneficial
  • Athletes who eat well-balanced meals generally do
    not need vitamin or mineral supplements

Nutrients of Special Concern Vitamin E and Iron
  • During prolonged, high-intensity physical
    activity, the muscles use of oxygen increases
    tenfold or more
  • increasing the production of free radicals in the
  • Vitamin E an antioxidant protects cells membranes
    against oxidative damage
  • Some athletes take megadoses of vitamin E to
    prevent oxidative damage to muscles
  • Supplementation with vitamin E does seem to
    protect against exercise-induced oxidative stress
  • There is little evidence it improve performance

Nutrients of Special Concern
  • Iron deficiency impairs performance by reducing
    aerobic capacity
  • Physically active young women are prone to iron
    deficiency due to
  • Iron losses in sweat
  • Small blood losses through the digestive track
  • Low intakes of high iron foods and
  • High iron losses through menstruation

Nutrients of Special Concern
  • Vegetarian female athletes are vulnerable to low
    iron and iron deficiency
  • The bioavailability of iron is often poor in
    plant-based diets because of
  • The high fiber and phytic acid
  • The iron in plant foods is not as easily absorbed
    as the heme iron in animal based foods
  • Good dietary sources of iron (fortified cereals,
    legumes, nuts, and seeds)
  • vitamin C rich foods should be included with each

Nutrients of Special Concern
  • Who needs iron supplements?
  • Many menstruating women border on iron
  • Teens of both genders because of growth, have
    high iron needs
  • Both groups may need supplements to correct an
    iron deficiency

Temperature Regulation Water
  • During physical activity
  • Dehydration is a real threat
  • A water loss of 1-2 of body weight can reduce a
    persons capacity to do muscular work
  • A person with a water loss of 7 is likely to
  • The exercising body loses water via sweat and
    exhaled vapor
  • Sweat cools the body
  • If heat builds up heat stroke may occur
    (increases body heat with loss of body fluid)

Temperature Regulation
  • Measures to prevent heat stroke
  • Drink enough fluid before and during activity
  • Rest in the shade
  • Wear lightweight clothing that encourages
  • Heat stroke symptoms
  • Clumsiness, Confusion or loss of consciousness,
    Dizziness, Headache Internal temperature above
    104F, Nausea, Stumbling, Sudden cessation of
    sweating (hot, dry skin)
  • This condition needs medical attention.

Temperature Regulation
  • Hypothermia
  • Below-normal body temperature in cold weather can
    pose as serious health threat
  • Early symptoms are shivering and euphoria
  • As body temperature falls
  • Shivering stops
  • Weakness, disorientation, and apathy set in
  • Even in cold weather, the body sweats and needs
  • The fluids should be warm or at room temperature
    to help prevent hypothermia

Fluid Needs
  • Endurance athletes can lose 2 or more quarts of
    fluid in every hour of activity
  • athletes must hydrate before and rehydrate during
    and after activity to replace all the lost fluid
  • Athletes are often advised to drink extra fluids
    in the last few days of training before an event
  • Extra fluid is not stored but ensures maximum
    tissue hydration
  • Thirst awareness occurs after fluid stores are
  • Dont wait to feel thirsty before drinking

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  • The best drink for most active people is plain
    cool water
  • Endurance athletes need more from their fluids
    than plain water
  • The first priority for endurance athletes should
    be replacement of fluids
  • To prevent heat stroke
  • The body also looses electrolytes in sweat
  • The minerals sodium, potassium, and chloride

Electrolyte Losses and Replacement
  • To replenish electrolytes in events lasting more
    than 1 hour
  • Sports drinks may be needed to replace fluids and
  • Sports drinks supply about 7 glucose
  • A carbohydrate concentration greater than 8 can
    delay fluid emptying from the stomach and slow
    down the delivery of water to the tissues

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Consumer Corner What Do Sports Drinks Have to
  • Sports drinks offer sodium and other electrolytes
    to help replace those lost during physical
  • Sports drinks taste good
  • If the drinks tastes good, people may drink more,
    ensuring adequate hydration
  • Fitness water does not provide glucose and

Sodium Depletion
  • When athletes compete in endurance sports lasting
    longer than three hours
  • Sweating over a long period of time can cause
    sodium depletion (hypoatremia)
  • Hypoatremia symptoms are similar to
    dehydrationBloating, Puffiness from water
    retention, Confusion, Seizure, Severe headache,
  • To prevent hypoatremia, endurance athletes should
    use sports drinks over water and eat salted
    pretzels in the last half of a race
  • Some may need beverages with higher sodium
    concentrations than commercial sports drinks

Other Beverages
  • Caffeine
  • Moderate amounts of caffeine one hour prior to an
    activity may assist athletic performance and at
    other times seem to have no effect
  • Athletic competitions limit the amount of
    caffeine that can be consumed within two hours of
    an event
  • Carbonated Drinks
  • The air bubbles from the carbonation make a
    person feel full quickly and may limit fluid

Other Beverages
  • Alcoholic beverages are inappropriate as fluid
  • Alcohol is a diuretic
  • It promotes the excretion of water, thiamin,
    riboflavin, folate, calcium, magnesium, and
  • Alcoholic beverages…
  • Impair temperature regulation
  • Alter perception and reaction time
  • Reduce strength and endurance
  • Impair judgment

Food Feature Choosing a Performance Diet
  • Many different diets can support an athletes
  • Athletes should eat for energy and full glycogen
  • Endurance athletes should aim for an average
    intake of 50 calories /kg of body weight
  • high in carbohydrate (60-70 of total calories)
  • moderate in fat (20-39),
  • adequate in protein (10-20)

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Food Feature Choosing a Performance Diet
  • Recommendations for a pregame meal
  • The foods should be high in carbohydrate
  • Easy to digest and contain fluids
  • It should be eaten 3 - 4 hours before competition
    to allow time for the stomach to empty

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Food Feature Choosing a Performance Diet
  • Drinks or candylike sport bars claim to provide
    complete nutrition
  • Mixtures of carbohydrate, protein, fat, some
    fiber, and certain vitamins and minerals
  • Usually taste good
  • Provide additional food energy before a game or
    for those needing to gain weight

Controversy Ergogenic Aids
  • Ergoenic aids
  • Appeal to performance-conscious people
  • Thought to enhance performance
  • Protein powders, amino acid supplements, caffeine
    pills, steroid replacers, muscle builders,
    vitamins, etc.

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Controversy Ergogenic Aids
  • Ergogenic Aids
  • For the large majority of ergogenic aids,
    research findings do not support the claims made
    for them
  • Almost anything can be sold under the label of
    dietary supplement with little regulation
  • They may contain added substances, lack purity
  • Consistent training and sound nutrition serve an
    athlete better than any pill, powder, or

Controversy Ergogenic Aids
  • Amino Acid Supplements
  • Are unnecessary
  • Healthy athletes eating a well-balanced diet
    never need them
  • In a few cases these supplements have proved
  • Amino acids complete for carriers
  • An overdose of one can limit the availability of
    some other amino acid

Controversy Ergogenic Aids
  • Caffeine
  • Provides mental stimulation and a physical boost
    during endurance sports
  • Some research supports this idea
  • Potential benefits from caffeine must be weighed
    against known adverse effects Upset stomach,
    nervousness, irritability, headaches,
    dehydration, and diarrhea

Controversy Ergogenic Aids Carnitine
  • A nonessential nutrient- the body can make plenty
    when needed
  • Marketed as a fat burner
  • In the body it helps transfer fatty acids across
    the membrane that encases the cells mitochondria
  • In scientific studies, carnitine supplementation
    for 7 to 14 days did not raise muscle carnitine
    concentrations or influence fat or carbohydrate
  • Supplements do not enhance exercise performance
  • Milk and meat products are good sources of

Controversy Ergogenic Aids Chromium Picolinate
  • Chromium is an essential trace mineral involved
    carbohydrate and lipid metabolism
  • The great majority of studies show no effects of
    chromium picolinate on body fatness, lean body
    mass, strength, or fatigue

Controversy Ergogenic Aids Creatine
  • Creatine safety
  • Long-term studies are lacking
  • Some studies suggest that creatine
    supplementation may enhance performance of
    high-intensity strength activity--weight lifting
    or repeated sprinting
  • Other studies have found no effect on strength
  • There is concern that children as young as 9
    years old take creatine with unknown consequences
  • Even diets high in creatine do not approach the
    amount athletes take in supplement form

Controversy Ergogenic Aids
  • Protein Powders/ Whey protein
  • Can supply amino acids to the body
  • Offers no special benefits beyond those provided
    by ordinary milk or yogurt
  • Extra protein
  • Will not stimulate muscle growth
  • Muscle growth is stimulated by physically
    demanding activity
  • Complete Meal Replacers
  • These bars and drinks taste good and provide
    extra food energy, largely as added fats and
  • They fall short of providing complete nutrition

Controversy Ergogenic Aids Anabolic Steroid
  • Often athletes take these drugs and related
    products without any medical supervision or
  • The testes and adrenal glands in men and the
    adrenal glands in women make anabolic steroid
    hormones naturally
  • In the body, these steroids produce accelerated
    muscle bulking in response to physical activity
  • Injections of these fake hormones produce
    muscle size and strength far beyond that
    attainable by training alone
  • At the price of great risks to health

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Controversy Ergogenic Aids Anabolic Steroid
  • The AAcademy of Ped the Amer Coll Sports Med, and
    the International Olympic Com maintain that
    taking these drugs is a form of cheating
  • Steroids produce changes in the brain that in
    some people bring on overly aggressive behavior,
    called steroid rage

Controversy Ergogenic Aids Steroid Alternative
  • Andro or DHEA claim
  • They reduce fat, build muscle, slow aging--
    are unsupported by research
  • Some effects of steroid alternatives include
  • Oily skin, Acne, Body hair growth, Liver
  • Irreversible masculine changes in females
  • Irreversible feminine changes in males
  • Aggressive behavior
  • Long-term effects, such as serious liver damage,
    may occur after years of use
  • Particularly vulnerable to these effects are
    children and adolescent athletes

Controversy Ergogenic Aids Human Growth Hormone
  • The U.S. Olympic Committee bans HGH use and
    maintains that it is a form of cheating
  • It can induce huge body size
  • It is less readily detected in drug tests than
  • Athletes in power sports are most likely to
    experiment with HGH
  • HGH causes the disease acromegaly
  • Widened jawline and nose, protruding brow, buck
    teeth, huge body, abnormally enlarged bones and

Controversy Ergogenic Aids
  • Drugs Posing As Supplements
  • Some ergogenic aids sold as dietary supplements
    can be powerful drugs
  • TRIAC a potent thyroid hormone has been recalled
    by the FDA
  • TRIAC interferes with normal thyroid functioning
    and has caused heart attack and stroke

Controversy Ergogenic Aids
  • Conclusion
  • Researchers identified over 300 products
    containing 235 different ingredients advertised
    as beneficial for muscle growth in a dozen health
    and body building magazines
  • None had been scientifically shown to be
  • Consistent training and sound nutrition are the
    best combination for athletic success