C H A P T E R 14

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C H A P T E R 14
BODY WEIGHT, BODY COMPOSITION, AND SPORT
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Body Composition
Body composition is a better indicator of fitness
than body size and weight. Being over-fat (not
necessarily overweight) has a negative impact on
athletic performance. Standard height-weight
tables do not provide accurate estimates of what
an athlete should weigh because they do not take
into account the composition of the weight. An
athlete can be overweight according to these
tables yet have very little body fat.
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DUAL-ENERGY X-RAY ABSORPTIOMETRY (DXA)
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COMPOSITION OF WEIGHT LOSS
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C H A P T E R 15
ERGOGENIC AIDS AND SPORT
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Caffeine (Stimulant)
Legal in low to moderate amounts
w Increases mental alertness, concentration,
catecholamine release, and mobilization and use
of FFA by the muscles
w Decreases fatigue and lowers perception of
effort
w Improves endurance performance may improve
sprint and strength performance
w Can cause nervousness, insomnia, tremors,
diuresis leading to dehydration, and heart
arrhythmias
4-7 cups of coffee consumed over a 30-minute
period could result in a positive urine test and
disqualification
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Caffeine Effects
Competitive cyclists pedaled to exhaustion at 80
VO2max after drinking a decaffeinated drink or a
caffeinated drink note that the lines for FFA
are incorrectly reversed. The caffeine group
exercised 20 longer than the decaffeinated group.
McArdle, Katch, and Katch, Exercise Physiology,
2001
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Effects of Bicarbonate Loading before and between
Exercise Bouts
The 5th bout was to exhaustion the
bicarbonate-loaded group went 42 longer than the
control group.
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Creatine
w Supplement proposed to increase muscle PCr
levels to better maintain muscle ATP levels
during intense exercise

• Studies report great variation in the effects
• 50 out of 92 studies show increased anaerobic
  power
• 12 out of 22 studies show increased anaerobic
  endurance
• 7 out of 16 studies show increased aerobic
  endurance
• Most studies show increased total body mass,
  probably primarily from increased water
  retention when coupled with weight training, it
  may increase fat-free mass

No major risks with small to moderate doses,
although some athletes would not want the
associated weight gain.
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C H A P T E R 16
CHILDREN AND ADOLESCENTS IN SPORT AND EXERCISE
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Aerobic Capacity in Children
w Relative to body weight, running economy is
lower inchildren compared to adults.
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Absolute (i.e., l/min) Relative to
body weight (i.e., ml/kg/min)
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Anaerobic Capacity in Children
w Ability to perform anaerobic activities is
lower than in adults
w Glycolytic capacity (i.e., glycolytic enzyme
levels) is lower
w Produce less lactate and cannot attain as high
RER values during maximal exercise as adults

• Anaerobic mean and peak power outputs are lower
  than in adults, even when scaled for body mass

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OPTIMAL ANAEROBIC POWER OUTPUT
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Resistance Training in Preadolescents
w May protect against injury and help build bones
w Improves motor skill coordination
w Increases strength largely through increased
neural activation of motor units
w Causes little change in muscle size (i.e.,
little hypertrophy) and is considered safe if not
overdone
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Thermal Stress and Children
w Evaporative heat loss is lower due to less
sweat produced by sweat glands.
w Acclimatization to heat is slower in boys than
adult men this presumably is also true in girls.
w Conductive heat loss and gain is greater
because of the childs greater ratio of body
surface area to mass, increasing risk for
hypothermia in cold environments and hyperthermia
in extremely hot environments (i.e., when
environmental temperature is higher than body
temperature).
w Exercising in extreme temperatures, both hot
and cold, should be minimized in children.
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C H A P T E R 17
AGING IN SPORT AND EXERCISE
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Of Mice and Men Voluntary Wheel Running in
Rats
One of the most difficult things to determine is
whether physiological deterioration with age is
due to aging per se or to the dramatic decrease
in daily activity levels. It is undoubtedly a
combination of the two.
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Body Composition and Aging A Double Whammy
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CHANGES IN MUSCLE MASS
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Strength Changes With Aging
w Maximal strength decreases
w Muscle mass decreases
w Percentage of ST muscle fibers increases
because of death of fast twitch alpha-motoneurons
followed by reinnervation of the denervated fast
muscle fibers by slow motoneurons, which converts
the muscle fibers to ST
w Total number and size of muscle fibers decreases
w Nervous system response slows
w Little change in oxidative enzyme capacity or
number of capillaries
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CHANGES IN STRENGTH WITH AGING
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Computed Tomography Scans of Arms of Three
57-Year-Old Men of Similar Body Weights
Biceps Brachii M.
Humerus
Triceps Brachii M.
Untrained Swim-Trained
Strength-Trained
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Aging versus Inactivity
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Aging versus Inactivity
Since physical activity tends to decline
substantially as we age, distinguishing between
the effects of aging and those of reduced
physical activity is difficult when studying
lifelong changes in physiological function.
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Trainability of the Older Athlete
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CHANGES WITH AGE IN RUNNING RECORDS
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CHANGES WITH AGE IN SWIMMING RECORDS
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C H A P T E R 18
SEX DIFFERENCES IN SPORT AND EXERCISE
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Biological versus Social Differences
Performance differences between men and women
likely result from biological differences as well
as social and cultural restrictions placed on
females during their development and the fact
that, historically, fewer women have competed in
athletic events than men.
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Body Size and Composition
w Major differences between boys and girls do not
occur until puberty
w Puberty in girlsestrogen causes pelvis
broadening, breast development, fat deposition in
hips and thighs, increased bone growth, and
faster closure of growth plates
w Puberty in boystestosterone causes increased
bone formation and muscle mass
w After puberty, girls average relative body fat
is about 10 greater than boys
w Men not only have a greater muscle mass, but
they carry a higher percentage of their muscle
mass in the upper body compared to women
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Strength DifferencesWomen and Men
w Innate qualities of muscle and motor control
are similar
w For the same amount of muscle, strength is
similar
w Muscle fiber cross-sectional areas are smaller
and muscle mass is less in women
w More muscle mass is proportionately distributed
below the waist in women
w Upper-body strength expressed relative to body
weight or fat-free mass is less in women
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MENS vs WOMENS STRENGTH
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Cardiovascular Responses in Women
w Higher heart rate response at rest and for same
absolute levels of submaximal exercise (about the
same Q as men)
w Lower SV at rest and at all exercise
intensities due to smaller heart size and smaller
blood volume
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Metabolic Responses in Women
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Training and Body Composition in Women
w Decreases in fat mass and increases in fat-free
mass (FFM), though women generally gain less FFM
than men.
w Losses in body mass are more related to energy
expenditure than to the participant's gender.
w Density of weight-bearing bones increases
equally in both sexes.
w Endurance training strengthens connective
tissue in both sexes.
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Strength Training Adaptations in Women
w Women's magnitude of strength gained from
resistance training ( increase) is similar to
men's.
w Women generally don't gain as much muscle size
as men from resistance training.
w Less muscle mass development is because of
lower testosterone levels.
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Female Athlete Triad
w Disordered eating
w Secondary amenorrhea
w Bone mineral disorders
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Possible Causes of Menstrual Dysfunction
w Prior history of menstrual dysfunction
w Acute stress (anxiety, depression, etc.)
w High training volume or intensity
w Low body weight or body fat fat converts
pre-estrogen steroids into estrogen, so low body
fat might affect estrogen levels
w Hormonal alterations e.g., training reduces LH
and FSH secretion
w Probably the most important factor inadequate
nutrition (energy deficit) and disordered eating
thus training can contribute to the energy
deficit Study 8 of 13 amenorrheic runners had
eating disorders, compared with 0 of 19
eumenorrheic runners