KNES 355 Intro to Growth (unit 1)

Why do we study GMD?

growth, maturation development

• to learn about normal pattern of biological variation at individual and population levels in humans

• once you understand normal patterns you can determine origins, causes and biological significance of variation

What can be modified during growth and development?

• physical env

• nutritional env

• training env

• social env

to optimize a child’s growth, health and performance potential

What is human biological variability?

• the range of possible values for any measurable characteristics (physical) of humans at the levels of

  • individual

  • group

  • pop.

What is biological variability influenced by?

genetics, prenatal env, nutritional status

What does somatic refer to?

• a body cell of an organism, usually with a diploid number of chromosomes in the nucleus

• tissues/organs or biological systems comprised of these cells

• gross morphological features such as height, weight and BMI

What are the steps of practical applications of understanding human variability?

1. Assess normalcy of GMD status

2. Assess normalcy of rates of change or progress

3. predict future outcomes (tracking)

4. interpret effect of physical activity or exercise on biological outcomes

What is the pediatric stage?

prenatal (1st, 2nd, 3rd trimester)

childhood (early, middle, late adolescence)

What is the adulthood stage?

young (19-40years)

middle (40-60)

older (60 years)

menopause and andropause happens between middle and older

What are the different parts of peri-natal and infancy?

prenatal: egg (twinning), embryo (sex and organ), fetus (growth)

Infancy: birth to one year

perinatal: 1st week of life

neo-natal: 1st month of life

postnatal: 2nd to 12th month of life

When is early childhood?

1-5 years

When is mid-childhood?

6-8 female

6-10 male

when is late childhood?

9-10 females

11-12 male

When is adolescence?

11-19 female

13-22 male

What is growth?

increase in size

What is maturation?

• progress towards mature state

• timing and tempo vary

• relates biological time to calendar time

What is development?

• behavior competence, learning appropriate behaviors expected by society

• cognitive, emotional, social and motor

One word to describe growth, maturation and development?

growth: distance

maturation: speed, timing

Development: driving rules

Growth requires:

a quantitative change in size

• not limited to childhood/adolescence

What is growth status?

• size attained at any point in time

• based on age and maturity

• compared with norms/references

things are only bigger or smaller by comparison

What is one of the best indicators of overall health and nutrition?

growth status

• reflects genetics and env, influences

• height and weight for age

• BMI for age = mass (kg)/height² (m)

What is hyperplasia?

increase in number of cells

What

What is accretion?

increase in interstitial material

Increase in muscle cell thickness and length does NOT equal:

increase in number of cells

• obvious shape change in muscle due to cell growth

How does growth in skeletal muscle tissue look like?

• cell number only increases until infancy and then stays the same

• cell size continues to rise from prenatal to adolescence but faster in childhood and adolescence

What is size?

• a difference in physical magnitude

• multi-dimensional at cell/tissue/body levels

• can be measured qualitatively and quantitatively (large/small)

From birth to 20 years, there is a change in:

mass distribution and segment lengths

What influences size in childhood?

• mostly growth but also tempo or rate of growth so also maturation

What is size influenced by in adulthood?

• due to residual growth potential and usually stops in mid 20s

What is the exception to how size is influenced?

• fat muscle bone

  • changes can be increased or decreased

  • mass, volume, thickness, density

variation in size due to different factors at different stages of the lifespan

Does size matter?

Yes

What is the NFL draftees size example?

• more that were drafted born early in the year

physically bigger= more coaching attention= more trained

What is the relative age effect?

• overrepresentation of children born earlier in the year on elite junior teams

• youth sports is typically arranged by chronological order

• often creates an advantage for oldest child in group

• coaches may mistake greater physical growth for greater ability

What are the implications of the relative age effect for older athletes?

• more likely to be selected for elite teams

• receive better coaching/training

• experience more success

• more likely to be viewed as gifted

What are the implications of the relative age effect for younger athletes?

• less likely to be selected for elite teams

• more likely to fall behind/dropout

• impact on self-perception

Size is a surrogate measure for __________ __________.

underlying pathology

👉 we use size as a stand-in (a clue) for what’s really going wrong inside.

What are the relevant size measures?

body mass, BMI

fat mass, fat %

bone density

What is shape?

• distribution of mass within an object

• change in geometric proportionalities

• has functional impacts

human shape changes with growth

Are there consequences to growth-related changes in shape?

yes

• changes may be beneficial, neutral or detrimental

• ex: female pelvis is wider and shallower compared to male pelvis

How can maturation be described?

• tempo and timing of physical changes

• progress towards a mature state

• maturation=process, maturity=status

• distance travelled on the way to adulthood

• most biochemical and physiological systems mature by an early adulthood

What are the characteristics of maturation?

• specific changes in tissues, organs and systems

• secondary sex characteristics only at puberty

• skeletal changes are continuous before birth to adulthood

• quantitative changes (size)

• qualitative changes (shape)

Growth recap

• primarily refers to size

• can be measured in height, weight, BMI

• can proceed without changes in maturation

Maturation recap

• primarily refers to tempo and timing of attaining size

• can be indicated by secondary sex characteristics, skeletal age, menarche, somatic age

• typically involves increased growth of some somatic features

What is the behavioral context of development?

• learning appropriate behaviors expected by society

• cognitive, emotional, social, moral, motor

What is the biological context of development?

• continuous, age-related, sequential

Growth vs. development

growth

• primarily refers to size

• chiefly structural

• easily measured (height, weight)

development

• complexity and progress

• chiefly functional

• more difficult to measure (neuromotor control, skill level, social behavior)

What is the difference between human vs. non-primate growth?

• extended childhood growth

• rapid adolescent growth

How is non-primate growth?

• growth and development is smooth and continuous from birth to adulthood

How is primate mammal growth different from non-primate growth?

• sexual development occurs long after infancy

• neurological development is 90% complete before a human can reproduce

What is scammon’s curves of systemic growth?

• as % of total gain between birth and 20 years

• differential tissue growth

• general growth curve (sigmoidal shape)

• body mass

• skeletal tissue

• cardiorespiratory system

the Scammon’s curves of systemic growth only represents ______ of height by the general curve, not the correct _________.

shape

numbers

How does maturation influence the growth curve?

• timing of change

• rate of change

• but not the FINAL ADULT OUTCOME

Human growth is different than animal growth because…

humans have extended childhood growth

What are the human growth features?

• the longest growing primates

• delayed somatic growth, not brain growth

• long period of infant dependency

• extended childhood growth period

• resurgence of rapid growth at adolescence

• followed by sexual and physical maturity

What is the most distinct aspect of human growth vs non human primates?

the delayed timing and rapid tempo of the human growth spurt

What are the advantages of human growth traits?

• extended period for brain development

• time for acquisition of survival skills, socialization, play, developing sociocultural skills

GMD are all influenced by:

Genetics: sets limits

Environment: sets likelihood of attaining potential (adult height)

Maturity: rarely influences final growth outcomes, but determines when you arrive (the age at which you achieve final height)