Nutrition and Physical
Activity
Chapter 13
Fitness
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Depends on physical activity and
exercise (not body type!)
Regular physical activity
 Promotes health
 Reduces risk of developing many
diseases
 Heart disease
 Cancer
 Stroke
 Diabetes
 Hypertension
More Benefits of Fitness
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Restful sleep
 Lower risk for some
types of cancer
Nutritional health
 Strong circulation &
Optimal body
lung function
composition
Optimal bone density  Stress reduction
 Cortisol reduction
Resistance to
infectious diseases
 Strong self image
Lower incidence of
 Lower risk of
anxiety & depression
dementia
How much should I do?
Highly individual
 Just 15-20 min/day starts to reduce
disease risk
 Minimum for optimal health: 2.5 hrs
moderate or 1.25 hrs vigorous activity

– Not an upper limit!
– Good to spread out over the week
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How much is too much?
Developing Fitness
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Minimizing risk of overuse injuries
 Be active all week
 Use proper equipment and attire
 Use proper form
 Include warm-up and cool-down activities
 Challenge your strength and endurance a
few times a week
 Mix it up!
 Pay attention to body signals
Developing Fitness
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Muscle conditioning
 Fit muscles use oxygen efficiently
 Increased mitochondria and vasculature
 Reduces heart’s workload
 Burns fat longer
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Balanced fitness program
 Activities you enjoy doing
 Addresses all aspects of fitness
 Strength, endurance, flexibility
 Each has specific benefits
Resistance Training
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Purpose
 Build muscle mass
 Increases metabolism!
 Develop and maintain muscle strength,
muscle power, and muscle endurance
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Benefits for prevention of chronic
diseases
Maximizes and maintains bone mass
Improves posture & reduces risk of back
injury
Nutrition & Physical Performance

Performance and recovery both enhanced by
optimal nutrition
– We need all essential nutrients to power
movement

3 energy systems:
– ATP-CP, lactic acid, and oxygen
– All 3 systems always active and work together

ATP-CP (creatine phosphate)
– Stores of ATP and CP only power muscles 3-15
seconds
– Muscle and liver glycogen needed to continue
contraction
Creatine Phosphate
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Popular supplement (ergogenic aid)
 Studies show improvement in muscle
strength and power
 No benefit for aerobic training
 Possible side effects:
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Weight gain (water retention)
GI symptoms: nausea, diarrhea, abdominal pain
Rash, anxiety, headache, fatigue
Not appropriate for people with kidney issues
Should be avoided in children, adolescents,
pregnant women, nursing mothers, diabetics
Anaerobic vs. Aerobic

Anaerobic activities and fatigue
– Lactic acid energy system
– Anaerobic glycolysis leads to drop in pH
– Impairs glycolysis, inhibits binding of
calcium
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Aerobic activities and endurance
– Oxygen energy system
– Oxidative metabolism of energy nutrients
– Increased blood flow to muscles: oxygen!
– Produces much more ATP, but at slower
rate
• Uses glucose and fatty acids
Endurance

As long as ATP supply meets energy
needs, activity can continue
– Rate/intensity of activity influences energy
system used
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Anaerobic exercise: CP and glycogen
rapidly depleted
– Level of training highly influences shift to
anaerobic metabolism
– Number of mitochondria and efficiency of
oxygen delivery increase with training
Glucose Use During PA
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Exertion
 Liver breaks down glycogen
 Release glucose into bloodstream
 Muscles use glucose and stored glycogen
 Muscle fatigue when glycogen is depleted
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Glycogen storage: limited
Intensity of activity
 Impacts how long glycogen will last
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CHO post-workout restores glycogen,
spares muscle tissue
Protein Use & PA
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Not a significant part of fuel mix for most
 Used in muscle building
 Synthesis suppressed during activity;
accelerates afterward
 High-quality protein consumption
 Enhances muscle protein synthesis
 What is a high-quality protein?
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Protein needs are higher for
endurance and strength athletes
 Need adequate CHO, as well…why?
Recommended Protein
Intakes for Athletes
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Endurance athlete: 1.2-1.4 g/kg body weight
Strength athlete: 1.6-1.7 g/kg body weight
Everyday adults: minimum of 0.8 g/kg body
weight
Max. usable amount for adults: 2.0 g/kg body
weight
Risks of excessive protein intake
– Dehydration
– Mineral losses
Vitamins and Minerals to
Support Activity
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Roles in supporting activity
 Assist in releasing energy from fuels
 Transport of oxygen
 Multiple vitamins and minerals, as well as
protein, involved!
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Supplements
 Vast majority do not enhance performance
well-nourished people
Fluids and Electrolytes to
Support Activity
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Fluid replacement via hydration
 Hydrate before activity
 Drink extra fluid in the days before event
 Rehydrate during and after activity
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Fluids for everyday, active people
 Plain, cool water
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Fluids for endurance athletes
 May benefit from mineral and CHOcontaining beverages
Sports Drinks vs. Water
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Sports drinks
 Hydration is critical to optimal
performance
 Water is best for most people
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Sport drinks offer the following
 Fluid
 Glucose
 Sodium and other electrolytes
 Some prefer the flavor
Dietary Strategies for Active
People
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Hydrate
 Thirst is a late signal of need
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Choose nutrient-dense foods
 Vitamins & minerals
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Consume adequate energy
 Need all energy-yielding nutrients
 CHO, protein, and fat
 Meal frequency and balance
 Stable blood glucose means stable energy levels
 Optimal maintenance of lean tissues
Timing of Meals
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30 min-1 hour pre-workout
 Protein-based snack or small meal
 Timing is individual
 Not for everyone! Depends on GI picture.
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During workout
 Sip water
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Post-workout
 Best time to consume CHO-rich foods
 Include protein! Balance.
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Fitness goals: highly individual!
 Timing strategies vary depending on goal
 Ex: carbohydrate loading