Motor Development - Exam 3

primary ossification centers

areas in the middle of long bones where bone cells are formed

muscular development pre-birth

hyperplasia & hypertrophy

muscle accounts for what % of weight at birth

23-25%

slow twitch fibers

type 1

fast twitch fibers

type 2

adipose development pre-birth

- first appears at 3.5 months

- increases rapidly last 2 months before birth

- accounts for 0.5kg body weight at birth

nervous system development pre-birth

- immature neurons form, differentiate, then migrate to their location

- 250,000 created per minute

- most have formed by 4th month, most have migrated by 6th month

- teratogens may disturb migration, branching, and pruning

skeletal development during adolescence

- bones grow at secondary centers at end of bones

- growth at epiphyseal plates usually stops by 18 or 19

appositional growth

bones increasing in girth

traction epiphyses

where muscle tendons attach to bones

muscular development during adolescence

- mainly hypertrophy

- follows sigmoid pattern

- mass grows in males until 17 years (54% body weight)

- mass grows in females until 13 years (45% body weight)

adipose development during adolescence

- fat increases rapidly until 6 months, then gradually until 8 years

- girls increase fat more dramatically than boys

- hyperplasia & hypertrophy

- subcutaneous fat increases from 6 or 7 - 12 or 13

- sub-q fat continues to increase in girls

endocrine development during adolescence

- excess or deficiency can alter growth

- growth hormone, thyroid hormone, & two gonadal hormones influence growth (they stimulate protein anabolism)

growth hormone

- secreted by anterior pituitary gland

- needed for normal growth

thyroid hormones

- influence whole-body growth & skeletal growth

gonadal hormones

- influence growth & sexual maturation

- androgens & estrogen

- quicken growth plate closure

androgens

- secreted by testes & adrenal glands

- promote growth of muscle mass

estrogen

- secreted by ovaries & adrenal cortex

- promotes accumulation of fat

nervous system development during adolescence

- brain grows rapidly after birth

- increase in neuron size, branching to form synapses, increase in glial cells, increase in myelin

- learning increases # of synaptic connections

- poor nutrition can stunt brain growth

skeletal development during adulthood

- bone remodels continuously throughout life

- bone growth slows & becomes more brittle

muscular development during adulthood

- by 80, 30% muscle mass is lost

- loss of mass is minimal until 50

adipose development during adulthood

- men & women tend to gain fat

- increase in trunk fat, decrease in sub-q fat on limbs

endocrine development during adulthood

- thyroid disorders more prevalent

- decreasing gonadal hormone levels associated with loss of bone & muscle tissue

nervous system development during adulthood

- neurogenesis

- theory: breaks in neural links cause detours & slowing

- exercise promoted improved cognitive function

anaerobic power

rate at which the body can meet demand for short-term intense activity

peak power

highest amount of power produced

mean power

average amount of power produced

anaerobic capacity

maximum oxygen deficit body can tolerate

anaerobic performance in adulthood

- performance is stable

- improvement reflects training

- around age 35, anaerobic capacity declines 8% per decade

gender differences in anaerobic performance

- men have advantage over women

- men & women decline sharply after 70, women decline faster

aerobic power

rate at which long-term oxygen demand is met

aerobic capacity

total energy available for prolonged activity

peak oxygen uptake

highest rate oxygen can be consumed by the muscles during aerobic work

aerobic performance during childhood

- smaller cardiac output compensated for with higher heart rates

- cannot exercise for as long as adults

- training yields significant improvements after puberty

changes in cardiovascular structure & function in adulthood

- loss of muscle & elasticity

- thickening of left ventricle

- fiber changes in valves

- max heart rate & cardiac output declines

- blood pressure increases

changes in respiratory structure & function in adulthood

- max oxygen uptake, stroke volume, & max cardiac output increases

- ventilation improves

long-term training effects

- women with more physical education exercise more frequently

- youth sport participation predicts young adult activity levels

- people engaged in lifelong activity had the highest max oxygen uptake

strength

the ability to exert force

isotonic/isokinetic strength

limbs move against resistance

isometric strength

strength exerted against immovable resistance

developmental changes in strength

- boys & girls have similar strength until age 13

- peak strength follows muscle peak

- more mature children are stronger

strength in middle/older adulthood

- strength declines gradually after 30s

- muscle mass declines in most older adults; some do not lose strength

flexibility

ability to move joints through a full range of motion

developmental changes in flexibility

- starts to decline in childhood

- girls more flexible

- flexibility varies in adolescence

flexibility in adulthood

- lose flexibility especially after age 50

- flexibility levels can be maintained