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Title: Introduction to Nutrition for Health, Fitness, and Sports Performance


1
Introduction to Nutrition for Health, Fitness,
and Sports Performance
Williams, 8th edition, Chapter 1
2
Starting Points
  • Review effects of regular exercise on risk for
    disease (Table 1.1)
  • Review health problems associated with poor
    dietary habits (Figure 1.5)
  • Define moderate amounts of physical activity
    (Table 1.2)
  • What is Sedentary Death Syndrome?Surgeon
    Generals Report on Physical Activity and
    Fitness weekly caloric expenditure from exercise
    should meet or exceed 1000 per week.

3
General guidelines for exercise (See pyramid -
Figure 1.3)
  • Level I 30 minutes daily low-intensity
  • Level II 3-6 days/week, gt 20 minutes at 50-85
    increase in heart rate
  • Level III 3-7 days/week stretching to? fitness
  • Level IV 2-3 days/week resistance activities
  • Level V physical inactivity (e.g. TV watching

4
Can too much exercise be harmful?
  • A few health risks of over exercising ?
    impaired immune function, increased risk of
    injury, and menstrual irregularities for women
  • See Revised Dietary Guidelines for
    Americanshttp//www.health.gov/dietaryguidelines
    /Key recommendations
  • http//www.health.gov/dietaryguidelines/dga2005/re
    commendations.htm

5
What is fitness?
  • Health related fitness
  • Body weight and body composition within normal
    range
  • Cardio-respiratory fitness
  • Adequate flexibility, strength, and endurance
  • Appropriate body composition
  • Sports-related fitness ability to maximize
    genetic potential with appropriate physical and
    mental training

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  • General definition of physical activity is any
    movement caused by muscle contraction that
    results in caloric expenditure.
  •  Components of Fitness
  • Flexibility
  • Strength
  • Endurance (muscular and cardio-respiratory)

9
  • Flexibility range of motion of a joint (e.g.
    lower back, hamstrings, shoulder rotation)
  • The structure of the joint itself, and the
    muscles and connective tissue (ligaments and
    tendons) that surround it restrict flexibility.
  • Using a variety of stretches will increase
    flexibility. Static stretches are most common,
    and involve putting the intended muscle to be
    stretched into a lengthened position and holding
    that stretch for at least 12 - 15 seconds

10
Muscular strength and endurance
  • Strength ability of muscles to move against
    force
  • Static or isometric strength muscle action
    with no noticeable change in muscle length (e.g.
    pushing against resistance)
  • Dynamic constant external resistance (DCER)
    training resistance training where external
    resistance of weight does no change joint
    flexion or extension occurs with each repetition
    (formerly known as isotonic exercise)
  • Dynamic strength measures are done using the one
    repetition maximum (1-RM) technique device used
    is a dynamometer.

11
  • Isometric force, no joint movement
  • Concentric force, while muscle is shortening
  • Eccentric force, while muscle is
    lengthening For strength training, apply
  •         Resistance
  •         Repetition
  •         Overload
  • Result ? hypertrophy

12
Isometric exercise
Source www.BodyliciousWorkout.com
13
Concentric exercise (biceps curl)
Source www.netfit.co.uk/ assets/bicep8m.gif
14
Eccentric exercise
Overhead squat Source http//www.hhs.csus.edu/ho
mepages/khs/Kilogram4/public/KINS20144/Kins144_OS
Q.htm
15
  • Muscular endurance ability of muscle to sustain
    repeated contractions
  • Measured by field tests (e.g. 60-second sit-up
    test, or measuring number of sit-ups done without
    rest.
  • Another test YMCA bench-press test involves
    performing standardized repetitions at a rate of
    30 per second.
  • Cardio respiratory endurance
  • Ability of heart, blood, and lungs to sustain
    moderate to high intensity exercise for 20
    minutes or more

16
  • Overall definition of nutrition sum total of
    processes involved in intake and utilization of
    food substances by living organisms, including
    ingestion, digestion, absorption, transport, and
    metabolism of nutrients in food
  • Sports-related fitness
  • Strength
  • Power
  • Speed
  • Endurance
  • Sport-specific neuromuscular motor skills

17
  • Ability to succeed in sports is largely related
    to
  • Genetic endowment
  • State of training
  • Nutritional status
  • Example losing excess body fat will enhance
    biomechanical efficiency
  • Consuming carbohydrates during exercise helps
    maintain normal blood sugar levels and delays
    fatigue
  • Adequate dietary iron prevents anemia and ensures
    maximal oxygen delivery to working muscles

18
  • Sports nutrition defined as the application of
    eating strategies to promote good health and
    adaptation to training, to recover quickly after
    each exercise session, and to perform optimally
    during competition (Louise Burke, in Williams,
    p. 14)
  • Are athletes getting adequate nutrition?
  • Groups that may be at risk due to restrictive
    dieting dancers, gymnasts, body builders,
    distance runners are most susceptible to
    inadequate diet

19
  • Malnutrition unbalanced nutrition (either over
    or under needs).
  • Basic purposes of food
  • To provide energy (calories)
  • To regulate metabolic processes
  • To support growth and development
  • Certain diet modifications will influence
    performance (e.g. high CHO? endurance)
  • Diet for training Depending upon length and
    intensity of exercise ? may need extra 500-1000
    extra calories a day. 

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What does a sports nutritionist do?
  • Sports nutrition is a specialty that requires
    traditional nutritional science studies (minimum
    - BS in Nutrition)
  • Involves investigation of interactions between
    dietary manipulations and physical performance
  • Assessments and recommendations given based on
    specific needs of athletes
  • Ongoing research and review of professional
    publications as well as attendance at annual
    professional meetings is necessary
  • See http//www.scandpg.org/ (Sports,
    Cardiovascular, and Wellness Nutritionists
    Dietetic practice group)

23
Chronic training effect
  • E.g. effect of early training for long-distance
    running increased hemoglobin and myoglobin
    production and cytochromes in muscle cells.
  • These demand increased iron - often a transient
    sports anemia may develop.
  • Excessive training may lead to chronic fatigue

24
Role of dietary supplements
  • DSHEA definition a food product that has at
    least one of following vitamin, mineral, herb,
    or botanical, amino acid, metabolite,
    constituent, extract, or combination of any of
    these
  • (Note that most Americans do not suffer from
    dietary deficiencies, yet over 40 regularly take
    supplements) 
  • NOTE Under DSHEA law (1994), any product sold as
    a nutritional product is free from FDA
    approval, but this does not mean that all
    products are safe. FDA must show in court that
    there is an unreasonable risk posed by a
    supplement to have it taken off market.

25
About supplements
  • 1.   No scientific body regularly recommends
    supplements
  • 2. Food is more than the sum of its nutrients ?
    may be other beneficial substances in food,
    making them a better choice. Also, nutrients in
    food and other food components may be better
    absorbed in combination than in isolation.
  • 3. Dietary supplements vary WIDELY in quality
    some brands may contain zero levels of the
    active ingredient

26
  • Ergogenic aid anything that increases work
    performance
  • Different classifications
  • 1. Psychological
  • 2. Physiological 3.  Pharmacological
  • 4.  Nutritional
  • While most nutritional ergogenic aids are legal,
    they may not all be safe.
  • Note dangers of ephedra, DHEA, androstenedione

27
  • Research and recommendations
  • 1.  Epidemiological studying large populations
    to find relationships between 2 or more
    variables researchers trace history and
    patterns. (example higher fat diets greater
    incidence of heart disease)
  • 2.  Experimental usually double-blind, placebo
    controlled lab-based setting, variables are
    manipulated.
  • 3. If study is done to determine effects of a
    supplement, good to have many variables tested.

28
  • Example a study on the effects of a CHO drink
    and endurance exercise may involve 2 groups an
    experimental group that would receive the
    high-CHO drink, and a control group that would
    receive a placebo drink. After administering the
    drink to both groups, they would perform an
    endurance activity (e.g. long distance run or
    cycle). Observations might include blood sugar
    levels at various time increments of the
    exercise, lactate threshold, rating of perceived
    exertion, and the length of time each participant
    was able to exercise.

29
  • The independent variable (IV) or the variable
    that could be manipulated would be the sports
    drink(high CHO or placebo)
  • The dependent variables (DV) would be blood sugar
    levels, lactate threshold, rating of perceived
    exertion, and the length of time of exercise.
  • Another example A study is conducted to examine
    the effects of pre-exercise fluidelectrolyte
    solution intake on rating of perceived exertion
    (RPE)
  • What is the IV? The DV?

30
Epidemiological research
  • Studying large populations to find relationships
    between 2 or more variables
  • People (subjects) may be followed for many
    years
  • Example Scientists may be looking at
    relationships between diet and exercise practices
    and health related indicators (e.g. blood
    pressure, Body Mass Index, blood glucose, heart
    disease)

31
  • Characteristics of sound research
  • What type of design was used (Experimental?
    Double blind?)
  • Placebo controlled?
  • Many variables?
  • Were extraneous variables controlled?
  • Background or credentials of researchers?
  • Who financed the study (is there a conflict of
    interest?)

32
What is a meta-analysis?
  • Review process that involves statistical analysis
    of previous studies.
  • Many studies on a particular subject are reviewed
  • Patterns are examined
  • (E.g. What are the findings from studies done
    over the last 20 years on the effects of caffeine
    ingestions on exercise endurance?)
  • May find meta analyses published in professional
    journals

33
Next topic
  • Review dietary recommendations for athletes
  • Must have good working knowledge of exchange
    lists and proposed new food guide pyramid
  • Read Rebuilding the Food Pyramid
  • Walter C. Willett and Meir J. Stampfer /
    Scientific American Jan03 at http//www.mindfully
    .org/Food/2003/Food-PyramidJan03.htm
  • Be prepared to discuss in next class!!
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