Fitness: Physical Activity, Nutrients, and Body Adaptations
I. Fitness
Fitness involves physical activity or exercise. The components of fitness are
cardiorespiratory endurance, flexibility, muscle strength, and muscle endurance. All of
these characteristics describe a healthy body. Today’s world encourages sedentary lifestyles
that foster the development of several chronic diseases.
A. Benefits of Fitness
1. Restful sleep
2. Nutritional health
3. Optimal body composition
4. Optimal bone density
5. Resistance to colds and other infectious diseases
6. Low risks of some types of cancer
7. Strong circulation and lung function
8. Low risk of cardiovascular disease
9. Low risk of type 2 diabetes
10. Reduced risk of gallbladder disease in women
11. Low incidence and severity of anxiety and depression
12. Long life and high quality of life in the later years
B. The 2005
Dietary Guidelines for Americans state that people need to participate in 30
minutes of physical activity most days of the week for health benefits and 60 minutes to
maintain a healthy body weight.
C. Developing Fitness
1. Guidelines for conditioning that are achieved through training. (getting F.I.T.)
a. Cardiorespiratory Endurance
1. Frequency – 3-5 days per week
2. Intensity – 55-90% maximum heart rate
3. Time/Duration – 20-60 minutes
b. Strength
1. Frequency – 2-3 days per week
2. Intensity – enough to enhance muscle strength, muscle endurance, and
improve body composition
3. Time/Duration – 8 to 12 repetitions of 8 to 10 different exercises
c. Flexibility
1. Frequency – 2-3 days per week
2. Intensity – enough to develop and maintain a full range of motion
3. Time/Duration – 4 repetitions of 10-30 seconds per muscle group
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2. The Overload Principle – to slightly increase comfortable capacity in each area. This
is also called the progressive overload principle.
a. Increase frequency – how often an activity is performed
b. Increase intensity – the degree of exertion while exercising
c. Increase duration – the length of time
3. The Body’s Response to Physical Activity
a. Hypertrophy is muscle gain in size and strength, the result of repeated work.
b. Atrophy is muscle loss in size and strength, the result of lack of activity.
c. Other Tips
1. Be active all week.
2. Use proper equipment and attire.
3. Use proper form when exercising.
4. Include warm-ups and cool-downs.
5. Challenge yourself, but not every time you exercise.
6. Pay attention to body signals.
7. Build intensity slowly.
4. Cautions on Starting
a. Healthy people can start with a moderate exercise program without seeking
medical advise first.
b. People with risk factors may need medical advice.
D.
Cardiorespiratory Endurance
Cardiorespiratory conditioning is measured by maximum oxygen uptake
(VO2max).
a. Increases cardiac output and oxygen delivery
b. Increases stroke volume
c. Slows resting pulse
d. Increases breathing efficiency
e. Improves circulation
f. Reduces blood pressure
2. Muscle Conditioning
a. Muscles use oxygen efficiently.
b. Muscles can burn fat longer.
3. A Balanced Fitness Program
a. Individualized
b. Cardiorespiratory
c. Muscle strength and endurance
d. Flexibility
e. Choose an activity you enjoy
1.
E. Weight Training is also called resistance training.
1. Increases muscle strength and endurance
2. Prevents and manages cardiovascular disease
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3. Enhances psychological well-being
4. Maximizes and maintains bone mass
5. Enhances performance in other sports
II.
Energy Systems, Fuels, and Nutrients to Support Activity
The mixture of fuels used during physical activity depends on diet, and intensity and duration
of the activity and training. Well-nourished active people and athletes do not need nutritional
supplements. Water, iron and sodium are nutrients that may need attention.
A. The Energy Systems of Physical Activity—ATP and CP
1. ATP is adenosine triphosphate – a high-energy compound that delivers energy instantaneously.
2. CP is creatine phosphate – a high-energy compound in the muscles, used anaerobically.
3. The Energy-Yielding Nutrients
a. Nutrients work together while one may predominate.
b. Depends on diet, intensity and duration of the activity, and training
1. Extremely intense activity
a. 8-10 seconds
b. ATP-CP (immediately available)
c. No oxygen needed (anaerobic)
d. Activity example – 100 yard dash, shot put
2. Very highly intense activity
a. 20 seconds to 3 minutes
b. ATP from carbohydrate (lactic acid)
c. No oxygen needed (anaerobic)
d. Activity example – ¼ mile run at maximum speed
3. Highly intense activity
a. 3-20 minutes
b. ATP from carbohydrate
c. Oxygen needed (aerobic)
d. Activity example – cycling, swimming, running
4. Moderately intense activity
a. More than 20 minutes
b. ATP from fat
c. Oxygen needed (aerobic)
d. Activity example – hiking
B.
Glucose Use during Physical Activity
1.
2.
3.
4.
5.
Diet Affects Glycogen Storage and Use
a. High-carbohydrate diets increase glycogen stores
b. Enhance endurance
Intensity of Activity Affects Glycogen Use
a. Moderate activities use glycogen slowly.
b. Intense activities use glycogen quickly.
Lactic Acid
a. Low intensity activities can clear lactic acid from the blood.
b. During highly intense activities lactic acid accumulates and activity can only be maintained for 1-3
minutes.
c. Lactic acid is converted to glucose in the liver (Cori cycle).
Duration of Activity Affects Glycogen Use
a. First 20 minutes – primarily use glycogen
b. After 20 minutes – use glycogen and fat
Glucose Depletion
a. “Hitting the wall” – exhaustion of glucose stores
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b.
6.
7.
8.
C.
Fat Use during Physical Activity
1.
2.
3.
D.
Duration of Activity Affects Fat Use
a. Beginning of activity uses fatty acids in the blood
b. After 20 minutes, uses body fat as major fuel
Intensity of Activity Affects Fat Use
a. As intensity increases, fat makes less of a contribution to the fuel mix
b. Oxygen must be abundant to break down fat
Training Affects Fat Use
a. The better trained the muscles, the more fat is used
b. The better trained, the stronger the heart and lung to deliver oxygen
c. If better trained, then hormones prevent glucose release from the liver, so they rely more on fat
Protein Use during Physical Activity—and between Times
1.
2.
3.
4.
5.
6.
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Maximizing Glucose Supply
1. High-carbohydrate diet – 8 g/kg body weight or 70% of total energy intake
2. Glucose during activities if activity last longer than 45 minutes (sports drinks, diluted fruit
juice)
3. Eat approximately 60 g of high-carbohydrate foods after activity.
4. Carbohydrate loading is a regime of diet and exercise that maximizes glycogen storage. It is
also called glycogen loading or glycogen super compensation.
Glucose during Activity
a. Activities lasting longer than 45 minutes
b. Light carbohydrate snacks under 200 kcalories
Glucose after Activity
a. High-carbohydrate meal within 15 minutes accelerates glycogen storage by 300%
b. High-carbohydrate meal within 2 hours and rate of glycogen storage declines by half
c. High-glycemic index foods
Training Affects Glycogen Use
a. Muscles that repeatedly deplete glycogen through hard work will store greater amounts of
glycogen.
b. Conditioned muscles rely less on glycogen and more on fat for energy.
c. Trained muscle cells have more mitochondria and can use oxygen better.
d. Untrained muscle cells depend more heavily on anaerobic pathways.
Protein Used in Muscle Building
a. Synthesis of protein is suppressed during activity.
b. After activity protein synthesis accelerates.
c. Repeated activities cause body adaptations to support needs.
d. Remodeling
e. Daily, ¼ to 1 ounce of body protein is added to muscle
mass during muscle-
building phase.
Protein Used as Fuel
a. During physical activity muscles use amino acids for fuel.
b. 10% of total fuel used
Diet Affects Protein Use during Activity
a. Diets rich in energy and carbohydrate allow the body to use less protein for fuel.
b. Carbohydrates spare protein.
Intensity and Duration of Activity Affect Protein Use during Activity
a. If glycogen stores get depleted, then more reliance on protein
b. Anaerobic strength training demands more protein to build muscles but not large amounts.
Training Affects Protein Use – the more trained the less protein used for energy
Protein Recommendations for Active People
a. Athletes in training need more protein than sedentary people.
b. Athletes in training need to meet energy and carbohydrate needs first.
c.
d.
e.
f.
E.
Vitamins and Minerals to Support Activity
1.
2.
3.
4.
5.
6.
7.
F.
Adult RDA: for males 56 g/day, for females 44 g/day
Strength athletes: for males 112-119 g/day, females 88-94 g/day
Endurance athletes: for males 84-112 g/day, females 66-88 g/day
U.S. average intake of protein: for males 95 g/day, females 65 g/day
Supplements
a. Do not enhance performance
b. Deficiencies may impede performance
c. Timing makes a difference; supplements take hours or days to combine with cells.
d. Nutrient-dense foods provide nutrients needed.
Vitamin E
a. Protects against oxidative stress
b. Does not improve performance
c. More research needed
d. Vegetables oils and antioxidant fruits and vegetables
Iron
a. Iron losses in sweat
b. Small blood losses in digestive tract
c. Poor iron absorption
Iron Deficiency
a. Common in physically active young women
b. Consume good dietary sources of iron
Iron-Deficiency Anemia
a. Impairs physical performance
b. Cannot perform aerobic activity and tire easily
Sports Anemia
a. Low blood hemoglobin for a short time
b. Adaptive, temporary response to endurance activity
c. Does not require supplementation
Iron Recommendations for Athletes
a. Blood tests should guide the decision
b. Depends on the individual
Fluids and Electrolytes to Support Activity
1.
2.
Fluid Losses via Sweat
a. Muscle heat is 15-20 times greater when active than at rest
b. Cooling mechanism
c. 1 liter of sweat dissipates 600 kcalories of heat
Hyperthermia – an above-normal body temperature
a. Body heat builds up
b. Triggers maximum sweating without sweat evaporation
c. Symptoms of heat stroke – a dangerous accumulation of body heat with accompanying loss of
body fluid
1. Headache
2. Nausea
3. Dizziness
4. Clumsiness
5. Stumbling
6. Hot, dry skin
7. Confusion or other mental changes
d. Prevention of heat stroke
1. Drink fluids
2. Rest in the shade when tired
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3. Wear appropriate clothing
Hypothermia – a below-normal body temperature
a. Symptoms
1. Shivering and euphoria
2. Weakness, disorientation, and apathy
b. Prevention
1. Drink fluids
2. Wear appropriate clothing
c. Water Recommendations
1. 1.0 to 1.5 mL/kcal expended
2. ½ cup per 100 kcal expended
4. Fluid Replacement via Hydration
a. Full hydration is imperative for athletes.
b. Those who are aware of their hourly sweat rate can replace lost fluids.
c. Plain, cool water is recommended.
d. Endurance athletes may require carbohydrate-containing beverages.
e. Hydration schedule
1. Two hours before activity – 2-3 cups
2. 15 minutes before activity – 1-2 cups
3. Every 15 minutes during activity – ½-2 cups
4. After activity – 2 cups for every pound of body weight lost
5. Electrolyte Losses and Replacement
a. Greater in the untrained
b. Training improves electrolyte retention.
c. Eat regular diet meeting energy and nutrient needs
d. Endurance athletes may need sports drinks.
e. Salt tablets worsen dehydration and impair performance.
6. Hyponatremia
a. Decreased concentration of sodium in the blood
b. Causes
1. Excessive sweat
2. Overhydration
3. Drinking sports drinks during an activity; sports drinks offer glucose polymers
c. Symptoms
1. Severe headache
2. Vomiting
3. Bloating
4. Confusion
5. Seizure
d. Prevention
1. Replace sodium during prolonged events.
2. Do not restrict salt in diets the days before events.
G. Poor Beverage Choices: Caffeine and Alcohol
1. Caffeine is a stimulant.
2. Alcohol is not the beverage to replace fluids and carbohydrate.
3.
III.
Diets for Physically Active People
A diet that provides ample fluids and nutrient-dense foods to meet energy needs will enhance an athlete’s
activity and overall health. Pregame and postgame meals should be light and carbohydrate rich.
A. Choosing a Diet to Support Fitness
1. Water
a. Thirst mechanisms are not as reliable
b. Must be replenished
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2.
Nutrient Density – consume nutrient-dense foods that are high in carbohydrate, moderate in fat, and
adequate in protein
3.
Carbohydrate
a.
b.
c.
d.
e.
4.
60-70% total energy intake
Avoid fiber-rich foods in the pregame meal.
Added sugar and fat may be needed during intensive training.
Liquid supplements should not replace foods.
8-10 g carbohydrate/kg body weight during heavy training
Protein
a. Strength athletes: for males 112-119 g/day, females 88-94 g/day
b. Endurance athletes: for males 84-112 g/day, females 66-88 g/day
5. A Performance Diet Example
a. Total kcalories – 3000
b. 63% kcal from carbohydrate
c. 22% kcal from fat
d. 15% kcal from protein
e. All vitamin and mineral RDAs are met
B. Meals Before and After Competition
1. Pregame Meals
a. Fluids
b. 300-800 kcalories
c. Carbohydrate-rich foods low in fat and fiber
d. Light and easy to digest
2. Postgame Meals
a. High-carbohydrate meals
b. Liquids often preferred
IV.
Performance-Enhancing Aids
It is difficult to distinguish valid versus bogus claims about ergogenic aids. Many individuals believe these
drugs, supplements, or procedures will enhance physical performance in activities. Some are harmless, some
have dangerous side effects, and some are costly. Most do not meet claims.
A. Ergogenic Aids
1. Problems with distinguishing valid claims versus bogus claims
2. Marketing techniques are used to generate sales.
3. Substances promoted as ergogenic aids
a. Arginine –
a nonessential amino acid
b. Boron –
a nonessential mineral
c. Brewer’s yeast is falsely promoted as an energy booster.
d. Cell salts
are sold as health promoting.
e. Coenzyme Q10 is not effective in improving athlete performance.
f. DNA (deoxyribonucleic acid) is falsely promoted as an energy booster.
g. Epoetin
is illegally used to increase oxygen capacity.
h. Gelatin
is not a strength enhancer.
i. Ginseng
has many side effects.
j. Glycine –
a nonessential amino acid
k. Growth hormone releasers do not enhance performance.
l. High doses of guarana can stress the heart and cause panic attacks.
m. Herbal steroids or plant sterols do not enhance hormone activity.
n. HMB (beta-hydroxy-beta methylbutyrate) claims to increase muscle mass and strength.
o. Inosine
has been shown to reduce endurance of runners.
p. Ma huang
has many dangerous side effects.
q. Niacin
does not enhance performance and has side effects.
r. Octacosanol
has false promotions.
s. Ornithine –
a nonessential amino acid
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t.
u.
v.
w.
x.
y.
z.
aa.
bb.
cc.
dd.
ee.
Oryzanol –
a plant sterol
Pangamic acid does not speed oxygen delivery.
Phosphate pills do not extend endurance or increase efficiency of aerobic metabolism.
Pyruvate
has common side effects of gas and diarrhea.
Ribose
has some false claims.
RNA (ribonucleic acid) does not enhance performance.
Royal jelly
is falsely promoted.
Sodium bicarbonate may cause intestinal bloating and diarrhea.
Spirulina
is potentially toxic.
Succinate
is not a metabolic enhancer.
Superoxide dismutase (SOD) is useless; it is digested.
Wheat germ oil is not an energy aid.
B. Dietary Supplements
1. Carnitine
a. Non-essential nutrient
b. Facilitates transfer of fatty acids across mitochondria membranes
c. Supplementation does not increase muscle carnitine or enhance exercise performance.
2. Chromium Picolinate
a. Essential mineral in carbohydrate and lipid metabolism
b. Supplementation has no effect on strength, lean body mass, or body fat.
3. Complete Nutrition Supplements
a. Taste good and provide food energy, but do not provide complete nutrition
b. Should not replace regular meals
4. Creatine
a. Some studies suggest improvement in muscle strength and size, cell hydration and glycogen
loading capacity
b. Safety issues and side effects
5. Conjugated Linoleic Acid (CLA)
a. Derived from linoleic acid, an essential fatty acid
b. Increases lean body mass in animals
c. Few human studies have been performed.
6. Caffeine
a. Caffeine can enhance performance by stimulating fatty acid release.
b. Adverse effects include stomach upset, nervousness, irritability, headaches, and diarrhea.
c. Use in moderation.
d. Use as an addition to other fluids, not as replacement.
7. Oxygenated Water
a. Oxygen cannot enter the bloodstream by way of the GI tract.
b. The body gets oxygen from the lungs.
C. Hormonal Supplements
1. Anabolic Steroids
a. Illegal
b. Authorities ban use
c. Plant sterols from herbs are poorly absorbed.
d. Dangerous side effects on the body and the mind
2. DHEA (dehydroepiandrosterone) and Androstenedione
a. Hormones that are precursors to testosterone
b. No evidence to support claims
c. Short-term effects are identified
3. Human Growth Hormone (hGH)
a. Used to build lean tissue and increase height if still growing
b. Extremely high cost
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c.
Many adverse side effects
1.
Define fitness, and list its benefits.
Fitness: the body’s ability to meet physical demands. Benefits: more restful sleep, improved nutritional health,
reduced fatness and increased lean body tissue, greater bone density, improved resistance to infectious diseases,
improved circulation and lung function, reduced risk of some cancers, reduced risk of diabetes, reduced
incidence and severity of anxiety and depression, improved self-image and self-confidence, long life, and
improved quality of life.
2.
Explain the overload principle.
The training principle that a body system, in order to improve, must be worked at frequencies, durations, or
intensities that gradually increase physical demands.
3.
Define cardiorespiratory endurance and list some of its benefits.
The ability to perform large-muscle dynamic exercise of moderate-to-high intensity for prolonged periods.
Benefits include support of ongoing action of the heart and lungs.
4.
What types of exercise are aerobic? Which are anaerobic?
Aerobic: requiring oxygen (swimming, cross-country skiing, rowing, fast walking, jogging, fast bicycling,
soccer, hockey, basketball, water polo, lacrosse and rugby). Anaerobic: not requiring oxygen (jump of
basketball player, weight lifting, sprinting).
5.
Describe the relationships among energy expenditure, type of activity, and oxygen use.
The mixture of fuels the muscles use during physical activity depends on diet, the intensity and duration of the
activity, and training. During intense activity, the fuel mix is mostly glucose (more anaerobic respiration),
whereas during less intense, moderate activity, fat makes a greater contribution (more aerobic respiration). With
endurance training, muscle cells adapt to store more glycogen and to rely less on glucose and more on fat for
energy.
6.
What factors influence the body’s use of glucose during physical activity? How?
The body’s use of glucose during physical activity depends partially on how much glycogen is in storage, and
this depends partly on the amount of carbohydrate eaten. Intensity of exercise influences the body’s use of
glucose—high-intensity activities require more glycogen. Degree of training to perform the activity is a factor
because the level of oxygen in the muscle influences the body’s use of glucose. During oxygen debt, glucose is
metabolized rapidly and pyruvate molecules accumulate in the muscle tissue. Duration of activity affects use of
glucose during exercise—within the first 20 minutes of exercise, the body primarily uses glucose.
7.
What factors influence the body’s use of fat during physical activity? How?
Duration of activity—when a moderate activity progresses past 20 minutes, the body uses more of its stored
body fat for energy; intensity of activity—as the intensity increases, fat makes less and less of a contribution to
the mixture of fuel used; degree of training—a well-trained body develops the adaptations that permit the body
to draw heavily on fat for fuel.
8.
What factors influence the body’s use of protein during physical activity? How?
Diet—people who consume diets rich in carbohydrate use less protein; intensity and duration of activity—
activities more intense and long in duration will use more protein for fuel; degree of training—athletes use more
protein as fuel than the unconditioned person.
9.
Why are some athletes likely to develop iron-deficiency anemia? Compare iron-deficiency anemia and
sports anemia, explaining the differences.
Iron-deficiency anemia is a condition that dramatically impairs physical performance. The athlete with this
condition cannot use fat for fuel or perform aerobic activities, and therefore will tire easily. Sports anemia is a
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transient condition of low hemoglobin in the blood, associated with the early stage of sports training or other
strenuous activity. It is an adaptive, temporary response to endurance training. Iron-deficiency anemia requires
iron supplementation, while sports anemia does not respond to such supplementation.
10. Discuss the importance of hydration during training, and list recommendations to maintain fluid balance.
If the body loses too much water, its chemistry becomes compromised and dehydration may result, which can
turn into heat stroke in hot, humid weather. Recommendations are to drink enough water or diluted juice before
and during training and competition, rest in the shade when tired, and wear lightweight clothing.
11. Describe the components of a healthy diet for athletic performance.
A nutrient-dense diet composed mostly of unprocessed foods that meets nutrient, fluid, and energy
requirements.
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Physical Activity Self-Evaluation
Fitness depends on a certain minimum amount of physical activity. Ideally, the quantity and quality of the physical
activity you select will improve your cardiorespiratory endurance, body composition, strength, and flexibility.
Examine your activity choices by keeping an activity diary for one week. For each physical activity, be sure to
record the type of activity, the level of intensity, and the duration. In addition, record the times and places of
beverage consumption and the types and amounts of beverages consumed. Now compare the choices you made in
your one-week activity diary to the guidelines for physical fitness.
1.
How often were you engaged in aerobic activity to improve cardiorespiratory endurance? Was the intensity of
aerobic activity between 55 and 90 percent of your maximum heart rate? Did the duration for each session last
at least 20 minutes?
2.
How often did you participate in resistance activities to develop strength? Was the intensity enough to enhance
muscle strength and improve body composition? Did you perform 8 to 10 different exercises, repeating each
one 8 to 12 times?
3.
How often did you stretch to improve your flexibility? Was the intensity enough to develop and maintain a full
range of motion? Did you hold each stretch 10 to 30 seconds and repeat each stretch at least four times?
4.
Do you drink plenty of fluids daily, especially water, before, during, and after physical activity?
5.
What changes could you make to improve your fitness?
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PERSONALIZED EXERCISE SELECTION
Below is a list of exercise activities which can help you reach your fitness goals. Cross out those activities you
cannot do....then go back and cross out those you will not do. What is left is your personalized exercise
program.
Aerobic Exercise
___walk briskly
___swim laps
___climb stairs
___aerobic dance
___stationary cycling
___kickboard in pool
___hike in country
___row on a rowing machine
___jump on a mini-tramp
___bicycle
___treadmill walking
___arm chair aerobics
___mall walking program
___jog\run
___roller blading
___water aerobics
___nordic track skiing
___arm ergometer work
___stair machine climbing
___jog/walk in pool
___cross country ski
___step aerobics
___canoe/skull/row
___disco/folk/square/tap dance
___roller skate/ice skate
Resistance/Strength Training
___calisthenics
___resistive water exercise
___free weight training
___dance exercise floorwork
___elastic resistance
___cable pulley system exercise
___lifelines
___weight training machines
___isometric exercise
Flexibility Activities
___yoga
___static stretching
___active stretching (warm-up type)
___ballet/dance (bar work)
Entertainment Exercise
Remember: You don’t necessarily get fit by playing sports, you should be fit to safely play sports. Once you gain
enough strength/endurance etc. to participate, these activities can help you maintain that fitness level, however, sport
activities always have a greater risk of injury than do fitness activities.
___tennis
___basketball
___gardening
___bowling
___sailing/surfing
___dancing
___racquetball
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___golf
___table tennis
___downhill skiing
___water skiing
___horseback riding
___squash/handball
___other_______________________