Adolescent Physical & Motor Development

puberty

• One definition may be 12-18

• Represents approximately 6 years of 33% of child’s growth (from birth to 18)

• May be divided into Younger [12-15] and older [16-18]

1.5- 2

girls enter adolescence _ years proior to boys

adolescence (biologic)

Changes in height, weight, physical appearance and physiological function (including sexual maturity) relating to a mature body

psychologic 

probably the best known of the adolescent challenges

wagner’s model (1996)

Optimal development a factor of 6 domains:

• Biologic

• Cognitive

• Emotional

• Social

• Moral

• Vocational

multifactorial

age of onset is _

• as we’ve seen throughout infancy and childhood, developmental age is much more important than chronologic

• Multifactorial issues include heredity, environment, and the influence of gonadotrophic hormones that regulate release of estrogen and testosterone

skeletal age 

• Most commonly utilized for orthopedic decisions

• Assessed by radiography comparing ossification of primary and secondary centers in bone with a set of radiograph norms depicting the expected level of bone development for a particular age group

• Left wrist and hand commonly used

genital maturity (tanner stages- also known as sexual maturity rating SMR)

• Most common Pediatric Usage

• Visual inspection during physical exam

• Stage 1:  Preadolescence

• Stage 2:  Early adolescence

• Stages 3 & 4:  Middle Adolescence

• Stage 5 Adulthood

stage 1: preadolescence

Absence of pubic hair and flat breasts in females and absence of pubic hair in men

stage 2: early adolescence 

Sparse pubic hair, raised breasts in females; darkened pubic hair and enlargement of testes in males

stage 3: middle adolescence

Coarsing and curling of pubic hair in boys and girls

• female; enlargement and raised breasts

• males: enlarged penis

stage 4: middle adolescence

Girls areolas and nipple form a separate contour

Males continued growth of penis

stage 5: adulthood 

Adult genitalie evident

onset of mearche

Definitive event for advent of puberty in girls

Age of onset (for 95% of population)

• Chronological age of 11-15 years (mean =12.5)

• Skeletal maturity 12-14.5 bone age

factors influencing age of menarche

• Downwaard trend of 2.3 months per decade

• 1910=14.5 years

• 1970=12.5 years

• Strenuous prepubescent exercise

• Regions of the world — central: earlier; northern/southern: late

• Seasons of the year — June & July

body configuration during birth 

• At birth:  Head =25% of body length; lower limbs =15%

• Legs and trunk lengthen with growth; therefore midpoint descends with age

• Center of Gravity

  • At birth, located at level of xyphoid

  • At maturity, located at S2, 3

endopmorh

round and fat

mesomorph

muscular

ectomorph

tall and thin

girls 

have shorter legs and wider pelvis = lower COG = advantage for balance activities at which adolescent girls out perform boys

boys

longer legs and narrow, higher pelvis; advantage for running and jumping

have wider shoulder and longer arms; advantage for throwing and striking

first year body length

Increases 50 percent in boys and girls

Then 5-6 cm per year, growth in length consistent and boys and girls similar

During adolescent growth spurt 20% of adult stature is attained

Occurs for approximately 2.5-3 years

girls growth spurt 

onset at 10-11 years; rate is 3” per year with peak velocity at 12

boys growth spurt

onset is 12-14 years, rate is 4 “ per year

Spurt is more rapid and longer

Peak velocity at 14

become taller than girls after 13

95% adult stature reached

95% by 18 years, last 2% by 20^th birthday

pattern of growth

• Orderly

• Foot length first followed 6 months later by leg and thigh

• 50% of lower limb growth occurs at the distal femoral epiphysis

• Upper extremity lags behind lower extremity

• Trunk growth responsible for increase in height

cessation for growth in length 

• Epiphyseal fusion

• Iliac crest epiphysis ossification

• Begins approx 14 yo finish at 25

  • Progresses from proximal to distal

  • Last epiphysis to close is sternal end of clavicle

  • Iliac crest closes within most girls within 6 months of menarch (menstrual period)

factors controlling growth in length

• External include food supply and absence of disease

• Homonal prepubescence include phyone, a pituitary hormone

• Pubescence posterior hypothalamus;anterior pituitary and classic hormones, growth thyroid, insulin, androgen and estrogen

first year body weight

• First year of life - body weight triples

• From 2 to 4 there is a constant increase of 4.5 lgs/yr

• From 4 to adolescence, slight increase and more variable  6.5 lbs.

• Adolescence girls: add 35 pounds

• Boys: add 45 pounds

• Peak velocity occurs 4-6 months after growth spurt

• Reason is change in height and body composition

changes in body comp

At 6 years: boys are 10% and girls 14%

At puberty boys increase to 13% but decrease again

Girls second growth spurt 20-25%

Adult men should be 10-25%; Women 18-30%

Minimum of concern too for men it is 5%; women 8%

BMI 

For both genders, _ increases from 5-59 yo but decreases after 60

child/adolescent obesity

• Some estimates of 1 in 3 are overweight or obese

• Childhood obesity has more than doubled in children from 7% to 18% and triples in adolescents from 5% to 18%

statistical defintion of obesity

• Usually greater than 95^th percentile BMI for age

  • Children with BMI values at 95^th percentile for age and gender have a greater than 60 percent chance of being obese at age 35

• Risk is greater than 85% BMI for age

relationship of obesity to motor development and performance 

In boys, for every 1% increase in body fat there is, on average, a 46 year decrement in distance covered during a 12 minute walk/run test

sedentary lifestyle and obesity

Skeletal effects include delayed longitudinal growth of extremities, not vertebrae

Diminishes cortical thickness

Length of bones little effected but bone density is

Increase risk factors for cardiovascular disease; more likely to have pre-diabetes

Social and psychological problems

Increased long term risk of cancers

interventions for obesity

Small changes approach was effective in reducing excessive weight gain

cardiac changes in adolescence 

Small changes approach was effective in reducing excessive weight gain

Cardiorespiratory development is related to growth and as body size increases so does capactiy

Increased body size is accompanied by an increase in cardiac dimensions which leads to an increase in stroke volume, cardiac output and VO 2 max

resting heart rate

boys 57-60; girls 62-63

Maximal heart rate:  195-220 bpm

cardiac parameters in adolescence

Stroke volume increases during grown spurt to 60 ml/beat at rest

Cardiac output increases through adolescence

vo2 max 

For boys, VO 2 max increases through adolescence and parallels increase in testosterone production

For girls, declines earlier and more quickly than boys

From 6-16 yo it is fairly constant @ 50-53ml/kg/min for boys

Reasons for earlier decline in girls is increase in body fat at maturation

cardiovascular endurance

Boys peaked at 16 years doing a timed one mile run in slightly over 8 minutes

Girls peaked at 14 yo at slightly over 11 minutes

motor skill performance

Boys peaked at 16 years doing a timed one mile run in slightly over 8 minutes

Girls peaked at 14 yo at slightly over 11 minutes

Girls out perform boys in: fine motor, flexibility and balance

Boys outperform girls in: gross, strength related such as chin-ups, sit-ups, jumping, running for speed, throwing and distance runs

reason for gender differences 

Increased body size

Decreased body fat

Increased secretion of androgen hormones

Increased blood hemoglobin

Larger heart and lungs

components of health related fitness

Body Composition

Cardiovascular

Muscular Strength and Endurance

Flexibility

flexibility

Static and dynamic components

No single good test

- Sit and Reach

Peak flexibility achieved during late teenage years or early 20s

Girls score higher than boys across all age groups; gender differences increase with increase in age

girls strength development

Consistent increase in grip strength

After 10-11, outscored by boys on 3 field tests: chin-up, pull-up, and sit-up

Strength spurt occurs during same year as height spurt

boys strength development

Consistent increase in grip strength

After 10-11, outscore girls on 3 field tests: chin-up, pull-up, and sit-up

Strength spurt lags behind height spurt by one year

aerobic training

Adolescents do not obtain the 15-20% gains seen in adults following _

High intensity programs are needed for change

Greatest response is obtained from least conditioned children