illinois state university body composition: children and maturation chapters 8 and 9

Illinois State UniversityIllinois State University

Body Composition: Body Composition: Children and MaturationChildren and Maturation

Chapters 8 and 9 Chapters 8 and 9

Total Body CompositionTotal Body Composition

Birth to Old AgeBirth to Old Age The human body goes through many The human body goes through many

changes when agingchanges when aging

InfantInfant

ChildChild

TeensTeens

Young AdultsYoung Adults

Middle-agedMiddle-aged

ParentsParents

SeniorsSeniors

MaturationMaturation

During childhood and adolescence, FFB During childhood and adolescence, FFB density progressively increases.density progressively increases.

As children age, the hydration of the As children age, the hydration of the FFB decreases and the mineral content FFB decreases and the mineral content increases.increases.

The classic 2-C models systematically The classic 2-C models systematically overestimate %BF of children and overestimate %BF of children and adolescents.adolescents.

Either the 4-C or 3-C (water) models Either the 4-C or 3-C (water) models should be used to obtain reference should be used to obtain reference measures of body composition for measures of body composition for children and adolescents.children and adolescents.

The overall density of the FFB tends to The overall density of the FFB tends to decrease with aging primarily due to the decrease with aging primarily due to the loss of bone mineral and skeletal loss of bone mineral and skeletal muscle mass.muscle mass.

There is a wide degree of inter-There is a wide degree of inter-individual variability in the FFB individual variability in the FFB composition of older men and women.composition of older men and women.

The classic 2-C models systematically The classic 2-C models systematically overestimates the average %BF for overestimates the average %BF for groups of older adults.groups of older adults.

NewbornsNewborns

Muscle comprises...Muscle comprises...• 27% N27% N• 33% K33% K• 28% water28% water

...of body’s total stores....of body’s total stores.

NewbornNewborn

Has a much smaller muscle mass than Has a much smaller muscle mass than the adult, about 25% versus 40% of the adult, about 25% versus 40% of body weight.body weight.

NewbornsNewborns

At birth, boys and girls do not differ in At birth, boys and girls do not differ in water, fat, protein, and osseous and water, fat, protein, and osseous and non-osseous mineral contents.non-osseous mineral contents.

In fact, data indicate marked similarity In fact, data indicate marked similarity between males and females at one between males and females at one month of age.month of age.

InfantsInfants

Changes in body components include Changes in body components include an 8 to 9% increase in fat mass to a an 8 to 9% increase in fat mass to a level of 22 to 24% at one year of age level of 22 to 24% at one year of age and a more than two-fold increase in and a more than two-fold increase in FFM.FFM.

InfantsInfants

The most notable change in the The most notable change in the constituents of FFM is a large shift of constituents of FFM is a large shift of water between the ECF (extracellular water between the ECF (extracellular fluid) and the ICF (intracellular fluid) fluid) and the ICF (intracellular fluid) compartments, although there is only a compartments, although there is only a slight increase in TBW (1-2%).slight increase in TBW (1-2%).

Childhood, Puberty, and Childhood, Puberty, and AdolescenceAdolescence

ChildhoodChildhood - period from infancy (ends at - period from infancy (ends at 1 yr) to puberty.1 yr) to puberty.

PubertyPuberty - state of physical development - state of physical development when sexual reproduction first becomes when sexual reproduction first becomes possible.possible.

AdolescenceAdolescence - includes puberty and - includes puberty and continues until sexual maturation is continues until sexual maturation is complete.complete.

Sex differences appear during Sex differences appear during childhood.childhood.• By the age of 5, bone mineral has By the age of 5, bone mineral has

increased from 3 to 3.6% of FFM in boys, increased from 3 to 3.6% of FFM in boys, but not in girls.but not in girls.

• %BF tends to be lower in boys (14.6%) %BF tends to be lower in boys (14.6%) than in girls (16.7%).than in girls (16.7%).

There is little or no change in %BF for There is little or no change in %BF for girls from 10 to 18 years, although total girls from 10 to 18 years, although total fat mass increases at an annual rate of fat mass increases at an annual rate of 1.14 kg per year.1.14 kg per year.

For boys, %BF decreases annually by For boys, %BF decreases annually by 1.15% across the age range.1.15% across the age range.

The water content of FFM is about 75% The water content of FFM is about 75% and 77% for boys and girls respectively.and 77% for boys and girls respectively.

There are gender differences during There are gender differences during adolescence in the growth of FFM.adolescence in the growth of FFM.

From 10 to 20 yrs, FFM increases by 33 From 10 to 20 yrs, FFM increases by 33 kg in boys, but only 16 kg in girls.kg in boys, but only 16 kg in girls.

The increase in FFM continues for a The increase in FFM continues for a longer period in males than in females; longer period in males than in females; adult levels are reached at 18 yrs in adult levels are reached at 18 yrs in females, but not until about 20 yrs in females, but not until about 20 yrs in males.males.

The major changes in the composition The major changes in the composition of FFM from pubescence to adulthood of FFM from pubescence to adulthood occur in the water and mineral portions.occur in the water and mineral portions.

These changes show that a multi-These changes show that a multi-component model is necessary in component model is necessary in children and adolescents for the children and adolescents for the estimation of body composition from estimation of body composition from body density.body density.

Young, Middle-Aged, and Older Young, Middle-Aged, and Older AdultsAdults

From 20 to 55 years of age, changes in From 20 to 55 years of age, changes in body composition are slower compared body composition are slower compared with those during childhood, with those during childhood, adolescence, or senescence.adolescence, or senescence.

It has been demonstrated that the It has been demonstrated that the average individual in this country will average individual in this country will gain approximately one pound of gain approximately one pound of additional weight each year after the additional weight each year after the age of 25 years.age of 25 years.

Such a seemingly small gain, however, Such a seemingly small gain, however, results in 30 pounds of excess weight results in 30 pounds of excess weight by the age of 55 years.by the age of 55 years.

Since the bone and muscle mass Since the bone and muscle mass decrease by approximately one half decrease by approximately one half pound per year due to reduced physical pound per year due to reduced physical activity, fat is actually increasing by 1.5 activity, fat is actually increasing by 1.5 pounds per year.pounds per year.

This means a 45 pound gain in fat over This means a 45 pound gain in fat over this 30 year period!this 30 year period!

BMC increases about 8% per year until BMC increases about 8% per year until adolescence.adolescence.

After adolescence the rate of increase After adolescence the rate of increase in BMC is slower in girls than in boys in BMC is slower in girls than in boys but continues until a peak BMC of 1000 but continues until a peak BMC of 1000 g is attained by women at 30-39 years.g is attained by women at 30-39 years.

In women aged 50-99 years, BMC In women aged 50-99 years, BMC decreases at a rate of 6-7% per decade.decreases at a rate of 6-7% per decade.

Males achieve adult mineralization by Males achieve adult mineralization by the age of 20 years with an average the age of 20 years with an average BMC of 1307 g, which remains constant BMC of 1307 g, which remains constant from 50-60 years. from 50-60 years.

A decrease in BMC in males begins A decrease in BMC in males begins between 60 and 70 years; the rate of between 60 and 70 years; the rate of decrease is about 10% from 70-85 decrease is about 10% from 70-85 years.years.

For women and men up to 70 yrs. of For women and men up to 70 yrs. of age, calcium and potassium are lost age, calcium and potassium are lost proportionally.proportionally.

In men older than 70 years, the In men older than 70 years, the TBCa/TBK ratio is higher, indicating a TBCa/TBK ratio is higher, indicating a greater loss of muscle mass than of greater loss of muscle mass than of bone mineral content.bone mineral content.

The non-muscle lean mass, mainly vital The non-muscle lean mass, mainly vital organs, does not change with age; total organs, does not change with age; total body protein (TBP) decreases 17% body protein (TBP) decreases 17% between ages 20 and 79 yrs.between ages 20 and 79 yrs.

Adults, like children and adolescents, Adults, like children and adolescents, change in body composition, but the change in body composition, but the changes during adulthood are slower.changes during adulthood are slower.

Some of these changes affect the Some of these changes affect the composition of FFM and thereby alter its composition of FFM and thereby alter its density.density.

There is a lack of research literature There is a lack of research literature concerning assessments of body concerning assessments of body composition by multiple models among composition by multiple models among ethnic groups.ethnic groups.

Most of our knowledge of changes in Most of our knowledge of changes in total body composition has been total body composition has been inferred from cross-sectional data, inferred from cross-sectional data, which can show the mean changes but which can show the mean changes but not individual variation.not individual variation.

Assessing Body Composition Assessing Body Composition

The skinfold equations recommended The skinfold equations recommended for children include the Lohman for children include the Lohman equation (7-17yrs) and the Slaughter equation (7-17yrs) and the Slaughter equation (8-17yrs)equation (8-17yrs)

Information on these equations can be Information on these equations can be found in Table 8.1, p. 113.found in Table 8.1, p. 113.

Assessing Body CompositionAssessing Body Composition

Ethnic specific SKF equations have Ethnic specific SKF equations have been developed for American Indian, been developed for American Indian, African American, and Caucasian African American, and Caucasian Children.Children.

Additional cross-validation studies are Additional cross-validation studies are needed to confirm the accuracy of these needed to confirm the accuracy of these equations for estimating %BFequations for estimating %BF

The Slaughter SKF equations provide a The Slaughter SKF equations provide a fairly reasonable estimate of average fairly reasonable estimate of average %BF for groups of African American %BF for groups of African American and Caucasian children and and Caucasian children and adolescents; however, for individuals adolescents; however, for individuals the prediction error is between the prediction error is between ++ 8-10% 8-10% BF.BF.

The Houtkooper BIA equation provides The Houtkooper BIA equation provides a fairly good estimate of body a fairly good estimate of body composition for groups of Caucasian composition for groups of Caucasian children and adolescents; the error for children and adolescents; the error for individuals may be as large as individuals may be as large as ++ 11% 11% BF.BF.

Compared to HW, ADP overestimates Compared to HW, ADP overestimates the average Db of children.the average Db of children.

DEXA typically underestimates average DEXA typically underestimates average %BF in older adults.%BF in older adults.

Preliminary findings suggest that HW Preliminary findings suggest that HW and ADP yield similar estimates of Db and ADP yield similar estimates of Db for groups of older men and women.for groups of older men and women.

More research is necessary to establish More research is necessary to establish the validity and applicability of prediction the validity and applicability of prediction equations for assessing body equations for assessing body composition of older adults from various composition of older adults from various ethnic groups.ethnic groups.

illinois state university body composition: children and maturation chapters 8 and 9

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