Age

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Age- Sex-Related Differences Their
Implications for Resistance ExerciseCh. 9
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• Resistance exercise- specialized method of
  conditioning that involves progressive use of
  resistance to increase ones ability to exert or
  resist force

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Children

• Preadolescence- period of life before development
  of secondary sex characteristics
• Adolescence- period between childhood adulthood
• Although there has been concern regarding
  potential negative consequences of intensive
  training on growth maturation, in adequately
  nourished children there is no clear evidence
  that physical training delays or accelerates
  growth or maturation in boys girls

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The Growing Child

• Growth- increase in body size or particular body
  part
• Development- describes natural progression from
  prenatal life to adulthood
• Maturation- process of becoming mature fully
  functional
• Puberty- period of time in which secondary sex
  characteristics develop child is transformed
  into young adult
• Changes also occur in body composition
  performance of physical skills

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Chronological vs. Biological Age

• Chronological age- stage of maturation or
  development by age in months or years
• Biological age- measured in terms of skeletal
  age, somatic (physique) maturity, or sexual
  maturation
• Because of considerable variation in rates of
  growth development between individuals, not
  always accurate to go by chronological age when
  assessing maturation

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• Common method of evaluating biological age
  developed by Tanner (Tanner Scale)
• Involves assessing development of identifiable
  secondary sex characteristics
• Breast development in girls
• Genital development in boys
• Pubic hair development in both sexes
• 5 stages Stage 1- immature, preadolescent state
• Stage 5- full sexual maturation

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• Training age- length of time child has been
  resistance training
• Can influence adaptations to RT
• Magnitude of gain in any strength-related measure
  is affected by amount of adaptation that has
  already occurred

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• Peak height velocity- pubertal growth spurt
• Young athletes may be at increased risk for
  injury during this time
• Risk factors for overuse injuries in children
• Relative weakening of bone
• Muscle imbalances between flexor extensor
  groups around a joint
• Relative tightening of muscle-tendon units
  spanning rapidly growing bones
• If young athlete complains of pain during growth
  spurt, may be overuse injury rather than growing
  pains

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Muscle Bone Growth

• During puberty
• 10-fold increase in testosterone in boys results
  in marked increase in muscle mass
• Increase in estrogen production causes increased
  body fat deposition, breast development,
  widening of hips in girls
• Muscle mass in girls increases at slower rate
  than in boys due to hormonal differences

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• Peak muscle mass occurs between ages
• 16-20 females
• 18-25 males
• Unless affected by resistance exercise, diet, or
  both
• Bone growth occurs on diaphysis growth
  cartilage (3 sites in child)
• Epiphyseal (growth) plate, jt. surface,
  apophyseal insertions of muscle-tendon units

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• Girls usually achieve bone maturity 2-3 years
  before boys
• Bones stop growing when epiphyseal plates become
  completely ossified
• Injuries to bone in adolescents typically occur
  in epiphyseal plates or growth cartilage due to
  trauma or overuse

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Developmental changes in muscular strength

• Important factor for expression of muscular
  strength in children comes from the development
  of the nervous system
• If myelination of nerve fibers is absent or
  incomplete, fast reactions skilled mvmts cannot
  be successfully performed, high levels of
  strength power are impossible
• Children should not be expected to respond to
  training the same way as adults until they reach
  neural maturity

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• Body types
• Mesomorph (muscular broader shoulders)
• Endomorph (rounder broader shoulders)
• Ectomorph (slender tall)
• Early-maturing children tend to be mesomorphs or
  endomorphs
• Late-maturing tend to be ectomorphs

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• Physical differences in body proportions can
  affect execution of resistance exercises
• More individualized programs are needed to be
  developed to address these differences in
  physical size maturity
• Differences in programs should be explained to
  children and the fact that motivation, coaching,
  ability contribute to success in sports

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Youth Resistance Training

• Resistance exercise can be safe effective
  method of conditioning for children
• Children should begin RT at level similar to
  their maturity, physical abilities, individual
  goals
• Adult programs philosophies are not appropriate
  for younger populations
• Better to underestimate childrens physical
  abilities gradually increase volume intensity
  than to overshoot their abilities risk injury
• Often experiencing training activities for 1st
  time

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Trainability of Children

• 1st studies suggested no increase in strength in
  preadolescents from RT
• Possibly from poor studies
• Recent studies have shown that boys girls can
  increase muscular strength above beyond growth
  maturation, provided that intensity volume of
  training are adequate
• Variability in changes can be due to program
  design, quality of instruction, background level
  of physical activity

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• Children participating in RT are likely to
  experience periods of reduced training or
  inactivity due to program design factors, busy
  schedules, extended travel plans, or decreased
  motivation
• The loss of training-induced strength gains (info
  from studies) from detraining shows importance of
  a maintenance program to maintain or slow loss of
  adaptations

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• Preadolescents seem to increase strength more
  through neural factors than through hypertrophy
  due to inadequate levels of testosterone
• During after puberty, strength gains are more
  associated with gains in muscle hypertrophy due
  to hormonal influences
• Females have limit of strength gains due to lower
  levels of testosterone

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Potential Benefits

• In addition to increasing muscular strength
  endurance, youth RT programs may
• Favorably alter selected anatomic psychosocial
  parameters
• Reduce injuries
• Improve motor skills sport performance
• RT probably has favorable influence on growth at
  any stage of development, as long as appropriate
  guidelines are followed
• RT should not stunt growth

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Potential Risks Concerns

• Appropriately prescribed youth RT programs are
  relatively safe when compared with other sports
  activities in which children participate
• Epiphyseal injuries are a concern among youth RT,
  but if children are taught proper technique, risk
  of injury is minimal

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• Greatest concern may be from repetitive-use soft
  tissue injuries
• Catastrophic injury can result if safety
  standards are not followed
• Qualified adult supervision
• Safe equipment
• Age-specific training guidelines

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Program design considerations for children

• RT should be part of well rounded exercise
  program
• No minimal age for participation
• Should have emotional maturity to follow
  directions eagerness to participate
• Should be screened for illness or injury to
  insure safe participation
• Goal of youth RT should be to increase muscular
  strength, but also educate children about their
  bodies, promote physical activity, have fun

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• 2 important areas of concern in developing youth
  RT program
• Quality instruction
• ST C pro should have understanding of youth
  training guidelines (Table 9.1)
• Rate of progression
• 1st establish rep range then determine load by
  trial error for safe amount
• Increase volume accordingly to keep program fresh
  challenging do not overdue

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Female Athletes

• Women are capable of tolerating adapting to
  stresses of RT the benefits are substantial
• Sex Differences
• Sex-related differences in physique, body
  composition, physiological responses to RT must
  be taken into consideration when designing RT
  program

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Body Size Composition

• No difference between ht., wt., body size
  between boys girls before puberty
• During puberty
• Estrogen in girls increases fat deposition,
  breast development, bone growth
• Testosterone in boys increases bone formation
  protein synthesis
• Boys tend to have longer growth period, therefore
  men tend to have greater statue than women

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• Adult women tend to have more body fat less
  muscle bone than adult males
• Women tend to be lighter in total body wt. than
  men
• Men have broader shoulders relative to their hips
• Women tend to have broader hips relative to their
  waists shoulders
• Women tend to have less muscle mass above the
  waist

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Strength Power Output

• Absolute strength
• Women have about 2/3 strength of men
• Absolute lower-body strength is generally closer
  to males than upper-body
• Relative strength
• Relative to body wt. women similar to men in
  lower-body strength, still less in upper-body
• Relative to fat-free mass strength differences
  tend to disappear
• Relative to cross-sectional area no differences
  between sexes, indicates that muscle quality is
  not specific

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• Power output
• Women about 63 of mens relative to body weight
• Relative to fat-free mass the gap narrows

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Resistance training for female athletes

• Despite sex-related differences, men women
  respond to RT in similar ways from pretraining
  baselines

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Trainability of Women

• Women can increase strength at same rate or
  faster than men
• Absolute gains in strength are greater in men,
  but relative increases are about the same or
  greater in women
• Muscle hypertrophy (increase in cross-sectional
  area) are similar between sexes

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Program design considerations for women

• With physiological adaptations to muscle the same
  in men women, there is no reason why RT
  programs need to be different
• Only real difference is amount of resistance used
  for a given exercise
• 2 areas of concern regarding women
• Development of upper-body strength
• Prevention of sport related injuries, especially
  knee (ACL)

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Age-related changes in musculoskeletal health

• Significant changes in body composition with
  advancing age can lead to development of physical
  functional impairments injury
• Bones become fragile with age because of decrease
  in bone mineral content
• Sarcopenia- loss of muscle mass
• Studies have shown decrease in cross-sectional
  areas of individual muscles, along with decrease
  in muscle density increase in intramuscular fat

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• Observed muscle atrophy with aging appears to
  result from physical inactivity gradual
  selective denervation of muscle fibers mostly
  Type II (fast-twitch)
• Daily activities require some power development
  decrease in ability to produce force may limit
  ability of older adults to safely climb stairs or
  walk

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Resistance training for older adults

• Aging does not appear to enhance or reduce
  ability of musculoskeletal system to adapt to RT
• Significant improvements in muscle strength,
  muscle mass, bone mineral density, functional
  capabilities have been observed in older people
  who participated in RT programs
• Improvements enhance exercise performance,
  decrease potential for injury, make activities
  of daily life more enjoyable

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Trainability of older adults

• If training stimulus is adequate, strength gains
  in older adults are similar to or greater than
  those in younger individuals
• Improvements in gait speed, stair climbing power,
  balance, overall spontaneous activity have been
  shown with RT

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• RT has been shown to have positive effect on
  energy balance increase in resting metabolic
  rate
• RT also has positive effect on bone health
• Interaction of hormonal nutritional factors can
  influence degree of benefit of exercise program

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Program design considerations for older adults

• Basically same design principles as younger
  people
• Prescreen all participants, since many older
  people suffer from variety of medical conditions
• Proper warm-up with low-intensity aerobics
  stretching
• Use resistance that does not overtax
  musculoskeletal system
• Start with 1 set of 8-12 reps progress to 3
  sets
• Can 1RM test if desired

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• Seniors should avoid doing Valsalva maneuver
• Allow adequate recovery between sessions 48-72
  hours
• Perform exercises within pain free ROM
• Trained instructors should supervise
• Proper nutritional guidelines should be followed
  to improve health optimize adaptations to RT