Transcript Slide 1

Fitness: Physical Activity,
Nutrients, and Body
Adaptations
Chapter 14
Fitness
• Depends on physical activity and
exercise
• Regular physical activity
– Promotes health
– Reduces risk of developing many
diseases
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Heart disease
Cancer
Stroke
Diabetes
Hypertension
Benefits of Fitness
 Restful sleep
 Nutritional health
 Optimal body
composition
 Optimal bone density
 Resistance to
infectious diseases
 Low incidence of
anxiety & depression
 Low risk for some
types of cancer
 Strong circulation &
lung function
 Low risk of cardiovascular disease
 Low risk of type 2
diabetes
 Strong self image
Benefits of Fitness
• Physical Activity Guidelines for
Americans
– Minimum amount of aerobic physical
activity
http://www.health.gov/paguidelines/
fact sheetprof.aspx
• Intensity of activity
• Extensive health benefits
• Develop and maintain fitness
– Cardiorespiratory endurance
– Body composition
Fitness and Mortality
Physical Activity
Pyramid
Guidelines for Physical Fitness
from American College of Sports
Medicine
Developing Fitness
• Goals
– Meet everyday demands of life
– Reasonable body weight & body
composition
• Components
– Flexibility- freely moving joints,
less risk of injury
– Muscle strength and endurancelonger, harder without fatigue
– Cardiorespiratory endurance
Developing Fitness
 Principles of conditioning (physical effect
of training)
 Progressive overload principle
 Frequency – more often
 More intensity
 Longer duration
 Body’s adaptation to physical activity
 Hypertrophy vs. atrophy
 Work different muscle groups from day
to day
 Make sure it is safe to start a program
 Progress slowly
 Alternate muscle groups from day to day
Build Fitness
Minimize Injuries
– Be active all week
– Use proper equipment and attire
– Use proper form (body mechanics)
– Include warm-up and cool-down
activities
– Challenge your strength and endurance
a few times a week
– Pay attention to body signals
– Work out wisely
Cardiorespiratory
Endurance
• Length of time a person can remain
active with an elevated heart rate
• Enhances capacity of heart, lungs,
and blood
– Oxygen Delivery
• Aerobic
• VO2 max is maximal O2 uptake, THE measure
of Cardiorespiratory fitness
– Waste Removal
• Brain and body benefit from more O2
Target Heart Rate
Cardiorespiratory
Endurance / Conditioning
 Aerobic workouts improve heart and lung
activities
• Cardiac output increases
• Enhanced oxygen delivery
• Increases blood volume per heartbeat
(stroke volume)
• Slower resting heart rate
• Breathing is more efficient
• Circulation improves
• Blood pressure falls
Cardiorespiratory
Endurance
and Conditioning
• Cardiorespiratory conditioning
– Activity must be sustained for 20
minutes or more
– Must use most of large-muscle
groups
– Intensity must elevate heart rate
– Perceived effort
• Still able to talk comfortably
Delivery of Oxygen by the Heart
& Lungs to the Muscles
Air (O2, CO2),
other gases
1
The respiratory system
delivers oxygen to the blood.
O2 CO
2
CO2
O2
2 The
CO2
O2
4
The blood carries
the carbon dioxide
back to the lungs.
circulatory
system carries
oxygenated blood
throughout the body.
O2
CO2
3 The
muscles and
other tissues obtain
oxygen from the
blood and release
carbon dioxide into it.
Cardiorespiratory
Endurance
• Muscle conditioning
– Fit muscles use oxygen efficiently
• Reduces heart’s workload
• Burns fat longer
• Balanced fitness program
– Level of intensity varies
– Can exercise at up to 90% of max.
heart rate
– Activities you enjoy doing
– Addresses all aspects of fitness
Resistance Training
• Purpose
– Build muscle mass
– Develop and maintain muscle
strength, muscle power, and muscle
endurance
• Benefits for prevention of
chronic diseases
– Maximize and maintain bone mass
– Improve posture & reduce risk of
back injury
– Strength vs. power vs. endurance
Nutrition and Exercise
• CHO and fat as fuel
• Protein to maintain and build
LBM
• Vitamins & minerals to
support energy metabolism
and tissue building
• Water to distribute the fuels
and dissipate heat and wastes
Energy Systems and Fuels
to Support Activity
• Adenosine triphosphate (ATP)
– Small amounts in all body tissues all the
time
– Delivers energy instantly
– Driving chemical force for muscle
contraction
– When ATP is split, energy is released as
• Mechanical movement
• Heat
Energy Systems and Fuels
to Support Activity
• Creatine phosphate (CP)
– Stored in the muscles
– Employed before ATP pools dwindle
• Split anaerobically to release
phosphate to replenish ATP
supplies
– CP supplies last 10 sec. for fast
energy (100-meter dash)
– CP reformed from P in ATP postexercise, during rest
Energy Systems and Fuels
to Support Activity
• Energy-yielding nutrients
– Prolonged demands of sustained
activity require continual ATP
– Breakdown of CHO, fat, protein
produces ATP
• Muscles use a mixture of these fuels
– Factors influencing fuel use
• Diet, intensity & duration of activity,
training
– Anaerobic activities – glucose
– Endurance activities – fats
Fuels Used for Activities of
Different Intensities & Durations
Split second
energy surge
to lift the barbells
involves
anaerobic work.
Sustained muscular efforts involve aerobic work
Moderate to high-intensity exercise uses some fat but more glucose for fuel.
Low to moderateintensity
exercise that can be
sustained for more
than 20 min uses
some glucose but
more fat for fuel.
Glucose Use During
Physical Activity
• Exertion
– Liver breaks down glycogen
– Releases glucose into bloodstream
– Muscles use serum glucose and stored
glycogen
– Muscle fatigue when glycogen is depleted
• Glycogen storage = 2000 kcal of energy
• Intensity of activity impacts how long
glycogen will last
– Moderate exercise uses glycogen slowly and
fatty acids / glucose as well
The Effect of Diet
on Physical Endurance
Maximum
endurance time:
Fat and protein diet
57 min
Normal mixed diet
114 min
High-carbohydrate diet
167 min
Glucose Use During
Physical Activity
• Lactate
– Glycolysis rate exceeds capacity of
mitochondria to accept H+ for ETC
– Accumulating pyruvate is converted
to lactate
• Recent news: Lactate in muscles does
not cause fatigue/soreness
– Lactate leaves muscle and travels to
liver
– Liver enzymes convert lactate back
into glucose to return to the
Glucose Use During
Physical Activity
• Duration of activity affects
glycogen use
– First 20 minutes or so of moderate
activity uses mostly glycogen
– Then liver gives up its glycogen
– After 20 minutes, fat starts to
displace glycogen as fuel
• Eventual glucose depletion
– Nervous system function declines
– Athlete “hits the wall”
Guidelines to Maximize
Glucose Supply
• Eat high-carbohydrate diet (70%)
all the time
• Drink glucose or sugarsweetened drinks during exercise
• Eat carbohydrate-rich food, at
least 60 g. CHO immediately after
activity
• Train the muscles to store as
much glycogen as possible
Glucose Use During
Physical Activity
• Glucose during activity
– Foods and beverages to be consumed
during activity
• 30 to 60 grams of carbohydrate per hour
during prolonged events (all-day hike)
• Glucose after activity
– Enlarges glycogen stores
• Best within 2 hours of activity
• High glycemic index better
Glucose Use During
Physical Activity
• Training affects glycogen storage
– Adaptation to continual hard work
• Conditioned muscles
– Rely less on glycogen
– Rely more on fat for energy
• Trained muscles use oxygen more
efficiently
– Have more mitochondria
Fat Use During
Physical Activity
• High-fat, low-carbohydrate diets
impair performance
– Smaller glycogen stores
• Some adaptation from more fat than CHO
– May experience greater fatigue, higher
perception of difficulty level
– Sports nutrition experts recommend 20
to 35% of energy from fat
• Body fat stores are another matter
Stored Fat Use During
Physical Activity
• Fat is liberated from internal fat
stores and fat under the skin
– Areas with most to spare, donate the
most
• Fatty acids released into blood not
muscles being used
– Blood delivers amount of fat each
muscle needs
– One arm can be stronger but both arms
store the same % fat
• Body fat is essential (remember
Stored Fat Use During
Physical Activity
• Strength/resistance training tone muscles
under the fat
• Duration of activity
– Epinephrine signals fat cells to break down
their TG and release fatty acids into blood
– Sustained, moderate activity raises serum TG
and continues to use TG for fuel for hours later
• Intensity of activity
– As intensity increases, less and less fat used.
Are you too out of breath? Less fat is being
burned.
• Training (repeated aerobic activity)
– More use of fat for fuel instead of glucose
– More and larger mitochondria, stronger
heart/lungs
Fat breakdown
comes only
from aerobic
metabolism.
Protein Use During
Physical Activity – and
Between Times
• Protein not a major fuel for
physical activity
• Used to build muscle and other lean
tissue between exercise times
– To some extent to fuel activity
• Protein is handled differently
during activity and rest
Protein Used in
Muscle Building
– Synthesis of body proteins suppressed
during activity, accelerates during
hours of recovery
– Repeated activity with slight overload
enhances muscle protein synthesis
– High-quality protein consumption
– Exercise signals DNA and RNA to
synthesize protein
– Weight training can add 1 oz muscle/day
Protein Used as Fuel
• Muscles speed up their use of
amino acids as fuel during an
activity
– 10% of total fuel during activity and
rest
• Diet adequate in energy and rich
in carbohydrate spare protein
• Intensity and duration
• Protein needs are higher for
endurance and strength athletes
Protein Use During
Physical Activity – and
Between Times
• Training affects protein use
– Higher degree of training, less
protein used during activity
• Protein recommendations
– Needs are greater for athletes in
training
– Need adequate carbohydrate intake
Recommended Protein
Intakes for Athletes
Vitamins and Minerals
to Support Physical
Activity
• Roles in supporting activity
– Assist in releasing energy from
fuels
– Transport oxygen
• Supplements in general
– Do not enhance performance of
well-nourished people
– Deficiencies impede performance
– Potential for deficiency by athlete
who is confined to a weight range
Vitamins and Minerals
to Support Physical
Activity
• Vitamin E
– Prolonged, high-intensity activity
• Increases free radical production
• Free radicals generated during exercise
may stimulate anti-oxidants in a
beneficial way.
– Food sources best
Vitamins and Minerals
to Support Physical
Activity
• Iron
– Deficiency particularly common
among active young women
– Vegetarian athletes most vulnerable
– Iron-deficiency anemia
• Impairs performance
– Sports anemia- temp. low Hgb
• Adaptive, temporary response
– Recommendations for athletes- get
a complete blood count (CBC)
Don’t
forget…
Water is
a nutrient
Fluids and Electrolytes
to Support Activity
• Water loss
– Sweating and breathing
– Dehydration risk
• Temperature regulation
– Hyperthermia- esp. in humidity
• Heat stroke prevention
• Symptoms- nausea, dizziness,
clumsiness, hot dry skin, confusion
– Hypothermia- long race on cold day
• Symptoms- shivering, euphoria→apathy
Fluids and Electrolytes
to Support Activity
• Fluid replacement via hydration
– Hydrate before activity
• Drink extra fluid in the days before
event
– Rehydrate during and after activity
• Fluids for everyday, active
people
– Plain, cool water
• Fluids for endurance athletes
– Carbohydrate-containing beverages
Hydration Schedule for
Physical Activity
Fluids and Electrolytes
to Support Activity
• Electrolyte losses and
replacementNa+, K+, Cl-,
Mg2+
– Losses occur with sweat
• Greatest in beginners
– Replacement
• Regular foods or sports drinks
• Hyponatremia
– Loss of body sodium accompanied by
excessive liquid consumption
Fluids and Electrolytes to
Support Activity
• Sports drinks
– Hydration is critical to optimal
performance
• Water is best for most people
– Sport drinks offer the following
•
•
•
•
Fluid
Glucose
Sodium and other electrolytes
Good taste
Fluids and Electrolytes to
Support Activity
• Enhanced water
– Lightly flavored
– Carbohydrates and electrolytes
• Caffeine
– Excesses can hinder performance
• Potentially danger in speeding heart rate
• Alcohol
– Negative effects
Diets for Physically
Active People
• Water
– Thirst is a late signal of need
• Nutrient density
– Vitamins, minerals, and energy
• Carbohydrates
– Pregame super high-carb meal
– Intensive training
• Protein
Diets for Physically
Active People
• Meals before and after
competition
– No single food improves skill, speed,
or strength, but favorite food is
good for psyche
– 125 g protein/d, 3000 kcal/d
– Pregame meal
• 300-800 kcal, 3 hrs prior to competition
– Postgame meal
• High-carbohydrate, moderate protein,
low-fat
Athlete’s Meal Selections
Breakfast
1 c shredded wheat
with low-fat milk and
banana 2 slices wholewheat toast with jelly,
1.5 cups orange juice
Lunch
2 turkey sandwiches
1 1/2 c low-fat milk, large
bunch of grapes
Total kcal: about 3000
63% kcal from carbohydrate
22% kcal from fat
15% kcal from protein
All vitamin and mineral
intakes exceed the RDA
for both men and women.
Snack
3 c plain popcorn, a
smoothie made from: 1
1/2 c apple juice 1 1 / 2
frozen banana
Dinner Salad: 1 c
spinach, carrots, and
mushrooms with 1/2 c
garbanzo beans, 1 tbs
sunflower seeds, and 1
tbs ranch salad
dressing 1 c spaghetti
with meat sauce 1 c
green beans 1 corn on
the cob 2 slices Italian
bread 4 tsp butter 1
piece angel food cake
with fresh strawberries
and whipping cream 1 c
low-fat milk
High-carbohydrate pregame meals
300-kcalorie meal
1 large apple
4 saltine crackers
1 1/2 tbs reduced-fat
peanut butter
500-kcalorie meal
1 large whole-wheat bagel
2 tbs jelly
1 1/2 c low-fat milk
750-kcalorie meal
1 large baked potato
2 tsp margarine
1 c steamed broccoli
1 c mixed carrots and
green peas 5 vanilla wafers
1 1/2 c apple or pineapple
juice
Highlight 14
Supplements as Ergogenic
Aids
Ergogenic Aids
• For most substances, research
does not support claims
• Some supplements are
contaminated
– Health risks
• Difficult to distinguish valid
claims from bogus ones
– Research findings presented out of
context
– Facts are often exaggerated and
Dietary Supplements
• Carnitine
– Promoted as “fat burner”
– Facilitates transfer of fatty acids
across mitochondrial membrane
– Good sources
• Chromium picolinate
– Essential trace mineral
• Involved in carbohydrate & lipid
metabolism
– Food sources
Dietary Supplements
• Complete nutrition supplements
– Fall short of claims
• Creatine
– Advertised as enhancing stores of CP
in muscles
– Performance enhancement
– Safety is under question
– Side effect of weight gain
Dietary Supplements
• Conjugated linoleic acid (CLA)
– Naturally occurring
polyunsaturated fatty acids
– Effect of CLA supplements on body
composition
• Caffeine
– Benefits
– Adverse effects
Hormonal Supplements
• Anabolic steroids
– Derived from male sex hormone –
testosterone
• Development of male characteristics
• Lean body mass
– Use is banned
– Risks associated with use
– Herbal alternatives
• “Natural” does not mean “harmless”
Hormonal Supplements
• DHEA and androstenedione
– Hormones made in the adrenal glands
• Precursors for testosterone
– Short-term side effects
– Long-term effects
• Human growth hormone (hGH)
– Acromegaly
– Other effects