GROWTH, DEVELOPMENT AND THE YOUNG ATHLETE

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GROWTH, DEVELOPMENT AND THE YOUNG ATHLETE

• Growth - Increase in the size of the body
• Height and Weight
• Exercise, adequate diet - essential for proper
  bone growth. Exercise affects primarily bone
  width, density and strength, no effect on length.
  
• BONES formed through ossification - spread from
  primary (diaphysis) and secondary (epiphysis)
  ossification centers.
• INJURY at epiphysis could cause early termination
  of growth. Competitive sports (baseball, soccer)
  - greatest risk for epiphyseal injury.

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• MUSCLE - growth accomplished by hypertrophy of
  individual muscle fibers (? myofilaments,
  myofibrils) muscle length - addition of
  sarcomeres and increase of length of existing
  sarcomers. Muscle mass peaks in females between
  16 - 20 years, in males 18 - 25 years.
• FAT - increase the size of existing fats cells,
  and increasing the number of fat cells. Amount of
  fat depends on diet, exercise, heredity at birth
  - 10 12 total body weight
  is fat. At maturity 15 in men, 25 ? in female.
• NERVOUS SYSTEM - myelination of the nerve fibers
  - necessary for fast reaction and skilled
  movements.

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PHYSICAL PERFORMANCE IN YOUNG ATHLETES

• Motor Ability - INCREASES UNTIL 18 YEARS
  of life, girls usually plateau around
  puberty (? estrogen levels ?
  greater fat deposition, more sedentary
  lifestyle).
• Strength - improves - muscle mass increase with
  age, dependence also on neural maturation
  (limited until myelinization completed)
• Pulmonary Function - ? all lung volumes until
  growth completed, PEFR also increases.
• VE max - 40 - 60 l/min for 4 - 6 year-old
  boys
• - 110 - 140 l / min at full
  maturity

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CARDIOVASCULAR SYSTEM

• Blood Pressure
  - directly related to body size
• DURING EXERCISE Lower SV - compensation by ?
  HR. a-v O2 difference increases.
• MAXIMUM HR higher - decrease with age (210 - 195
  min from 10 to 20 years).

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Aerobic Capacity

• VO2 max peaks between 17 - 21 in boys, 12 - 15 in
  girls.
• VO2 max relative to body weight
  - no difference to adults (performance is far
  inferior to adults, difference in
  economy of effort).

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Anaerobic Capacity

• Lower in children - ? glycolytic capacity
  because of ? amount of phosphorfuctokinase.
  Anaerobic mean and peak power outputs
  lower in children

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Thermal Stress

• Children - more susceptible to heat and cold
  induced illnesses or injury lower capacity for
  evaporative heat loss, sweat less. Greater
  conductive heat loss ?
  greater risk for hypothermia in cold.

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Training in Young Athlete

• Resistance (Strength) Training
• Resistance training - stronger, broader, compact
  bones. Training programs similar to adults
  program. Gains of strength by improved motor
  skill coordination, increased motor unit
  activation, other neurological adaptations

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Aerobic and Anaerobic Training

• Aerobic training does not alter VO2 max as much
  as would be expected (possibly because of small
  heart - ? SV, ? CO).
  Anaerobic capacity ? with anaerobic training.
• REGULAR TRAINING results in ? total body fat,?
  fat-free mass, ? total body mass.
• GROWTH AND MATURATION NOT SIGNIFICANTLY ALTERED
  BY TRAINING.

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AGING AND THE OLDER ATHLETE

• Sport Performance
• Physical Prime - during 20 s or early 30 s.
• Running Performance
• Decrease with age, not dependent of distance.
• Swimming Performance affected by aging
  in much the same manner as running.

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• Peak Performances in both strength and endurance
  events decrease by about 1 - 2
  ? per year, starting between 20
  - 35.
• Cardiorespiratory Endurance And Aging
• VO2 max decreases by about 10 ? per decade,
  starting in late teens in women and mid-20s for
  men, associated with decrease in
  cardiorespiratory endurance activity.

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• Decrease in VO2 max is not strictly
  a function of age - athletes continuing
  with training - significantly less decrease in
  VO2 max. With aging - more sedentary life, gain
  weight.
• Respiratory Changes With Aging
  ? VC,? RV, ? RV/TLC - less air exchange
  with each breath. VE max decreases (loss of
  elasticity of lung tissue and chest wall) a-v O2
  diff decreased - ? O2 extraction by muscles
  (reduction of blood flow to muscle)

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• Cardiovascular Changes With Aging
• Maximal HR decreases - 1 beat per year (HR max ?
  220 - age)
• SV and CO decrease with age
• ? HR max - decrease in sympathetic nervous
  system activity
• ? SV - ? TPR (reduced compliance
  of arteries, ? EF of left ventricle)

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• ALL CHANGES MINIMIZED BY TRAINING CONTINUATION
• MAXIMAL STRENGTH reduced with aging
  (? physical activity, ? muscle mass -
  reduced protein synthesis, loss of FT motor
  units).
• Training - lessen the impact of aging on
  performance (cant arrest the process of
  biological aging).
• Older people LESS TOLERANT OF ENVIRONMENTAL
  STRESS. Aging reduces thermal tolerance (? sweat
  production).

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• Body Composition
• With age -? BODY FAT, ? FAT-FREE MASS
  ? reduction in general activity levels.
• CAUSES ? dietary intake,? physical activity,
  reduced ability to mobilize fat. TRAINING can
  held these chances in body composition.
• ENDURANCE TRAINING IN OLDER INDIVIDUALS
• ? muscles oxidateve enzyme activities,
• ? muscle strength, muscle hypertrophy.

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GENDER ISSUES, FEMALE ATHLETE

• Body Size and Composition
• Until Puberty - no differences in body size and
  composition.
• At Puberty - estrogen - ? fat deposition (hips,
  thighs, ? rate of bone growth - final length
  earlier)
• Responses to Exercise
• Women - weaker (lower quantity of muscle, smaller
  muscle fiber cross - sectional area).
• Lower SV, Higher HR and SIMILAR CO for the SAME
  RATE OF WORK.

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• Lower SV - smaller LV and lower blood volume
  (smaller body size).
• VE max lower, mostly below
  125 l/min (highly trained till 250 l/min).
• VO2 max - lower when expressed in ml.kg.min.
  (extra body fat, lower HB leverls - lower oxygen
  content in arterial blood)

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• Highest VO2 max for female
  - 77 ml. kg. min and 94 ml. kg. min
  FOR MEN
• a-v O2 diff. - less increase - lower HB content,
  less O2 delivered to active muscles anaerobic
  threshold - little or no difference.

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Physiological Adaptations to Training

• Women gain LESS FAT FREE MASS, INCREASE IN
  STRENGTH (20 - 40 ?) in
  resistance training (due more to neural factors -
  increase in muscle mass small). Cardiovascular
  and respiratory changes accompanying ENDURANCE
  TRAINING - NOT SEX SPECIFIC.

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Athletic Ability

• SPECIAL CONSIDERATIONS unique to female
  menstruation, pregnancy, osteoporosis, eating
  disorders environmental factors.

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Menstruation and Performance

• Considerable INDIVIDUAL VARIABILITY
  in performance during different phases
  of menstrual cycle (no change x noticeable),
  no general pattern in achieving BEST PERFORMANCE
  during any specific phase. Women experiencing
  PREMENSTRUAL SYNDROM or DYSMENORRHEA -
  performance decrease.
• MENARCHE - coming later in highly trained
  athletes - not as a rule

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Menstrual Dysfunction

• Disruption of normal menstrual cycle.
• A high percentage of female athletes
  in endurance and appearance sports
  experience SECONDARY AMENORRHEA - normal
  menstrual function lost for months or years.
• REVERSIBLE - reduction in intensity and volume of
  training, increase in caloric intake

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Pregnancy

• During exercise - major concerns - risk
  of FETAL HYPOXIA (reduced blood flow
  to uterus),
• FETAL HYPERTHERMIA (? of mothers internal body
  temperature), ? CARBOHYDRATE SUPPLY TO THE FETUS,
  possibility of MISCARRIAGE PROPERLY PRESCRIBED
  EXERCISE program outweigh the potential risks
  (coordination with womans obstetrician)

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Osteoporosis

• Decreased bone mineral content - increased bone
  porosity - greater risk of fractures - increase 2
  - 5x starting with onset of menopause
• CONTRIBUTING FACTORS in postmenopausal women
  Estrogen deficiency, inadequate calcium intake,
  inadequate physical activity.

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Eating Disorders

• a) Anorexia Nervosa
• Females aged 12 - 21 are at greatest risk.
• SYMPTOMS
• INTENSE FEAR OF FATNESS, DISTORTED BODY IMAGE,
  REFUSAL OF MEALS, AMENORRHEA
• Higher Risk Sports - appearance sports (figure
  skating, gymnastics, ballet), endurance sports
  (distance running), weight classification sports
  (horse racing)

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• b) Bulimia Nervosa
• Episodes of binge eating (large amount
  of food in a discrete period of time), feeling
  lack of control over eating, purging behavior
  (self-induced vomiting, laxative use, diuretic
  use)
• Persistent overconcern with body shape and weight
• PREVALENCE in female athletes estimated as high
  as 50 ? for elite athletes in certain sports
• Female Triad - disordered eating, secondary
  amenorrhea, bone mineral disorders.

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Sex tests feminity control

• From 1968 to 2000 women athletes undergoing
  genetic testing to prove their sex
  before they could compete.

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Buccal smear XX chromosomes

• Since 2000 replacement X chromosome testing with
  DNA-based methods to detect Y chromosomal
  material, principally SRY sex determining locus.

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Since 2000 sex tests abandoned

• Gender verification has not been completely
  abandoned. Verification can be arranged, if
  athletes sex is called into
  question.

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Transsexual athletes

• After puberty male-female, female-male
  (1 in 12.000 men, 1 in 30.000 women).
  Criteria for competition (Olympic committee,
  2004)
• 1) Surgical anatomical changes completed,
  including external genitalia and gonectomy
• 2) Legal recognition of their assigned sex
  confered by appropriate authorities
• 3) Hormonal therapy administered for sufficient
  length of time to minimize gender-related
  advantages in competitions