W1 - Growth & Maturation Flashcards
Growth
Involves the increase in body size.
Whether that be its entirety or segments.
Incl. hyperplasia, hypertrophy and accretion.
What does the growth trajectory of a child depend on?
Tempo (rate of change)
Timing characteristics (Size at a given age).
Why should growth be plotted on a reference curve?
To capture variability + allow for assessment of the ind status over time.
Is stature growth a linear process?
no
What are the 4 patterns of growth that tissues and systems of the body follow?
Neurological
Genital
General
Lymphoid
What study designs are used in paediatrics growth studies?
Cross-sectional
Longitudinal
Mixed-longitudinal
Cross-sectional paediatrics growth study design
Single measurement from ind who differs in chronological age
Longitudinal paediatrics growth study design
Measure same ind over time with at least 3 serial measures on each individual.
Mixed-longitudinal paediatrics growth study design
Number of relatively short longitudinal studies interlocked to cover a wide age range.
OR
Some ind are repeatedly measured + others are only measured once.
Which study design can NOT provide info on an ind timing and tempo of growth?
Cross-sectional
What does BMI correlate well with for children?
Correlated well with estimates of body fatness in children but there is large variability present (r=~0.3-0.8)
BMI equation for growth
BMI = Body mass (kg) / stature^2 (m^2).
Maturation
Continous process of becoming fully mature until a defined endpoint.
Characterised by timing and tempo.
What are the most universally used indicators of biological maturity?
Maturation of the skeleton
Secondary sex characteristics
Age at peak height velocity (PHV)
Menarcheal status
What comes under secondary sex characteristics?
Genitals
Breasts
Pubic hair
Which indicators of maturation are moderately to highly correlated during adolescence?
Skeletal
Sexual
Somatic
Can just 1 indicator give a complete description of the tempo of growth and maturation?
NO
What does the discord among growth and maturation indicators reflect?
Ind variation in the timing and tempo of sexual and somatic maturation
+
Methodological concerns in assessment
What growth + maturation indicators should be used in studies making gender comparisons?
Skeletal age
or one of the somatic indicators
Why should biological maturation be considered in studies?
Due to the effects of a childs biological maturation potentially masking or being greater than the effects associated with exposure to physical activity or exercise.
What can almost correct when age misclassifies weight status?
Adjustment for maturity.
List the sexual maturation stages proposed by Tanner
Prepubertal
Peripubertal
Pubertal
Mature
Tanners Sexual Maturation Stages
Prepubertal
No pubic hair
No genital or breast growth
Tanners Sexual Maturation Stages
Peripubertal
Initiation of pubic hair, breast + genital growth.
Tanners Sexual Maturation Stages
Pubertal
Continued development of pubic hair, breast + genital growth
Tanners Sexual Maturation Stages
Mature
Adult like development of all characteristics
What does individual growth + maturation depend on?
Genotype
Phenotype
What happens to activity levels as you advance in the Tanner stages?
Declines
Pros to the Tanner Stages
Quick
Non-invasive
Allows participant to be classified with specific characteristics
Self-assessment is close to clinician assessment
No longitudinal analysis needed
Cons to the Tanner stages
Invasion of privacy
Limited to the pubertal phase
Requires training
Concerns about reliability within + between ind
Where in the Tanner stages would the Age of Menarche Marker occur?
In the midrange
How would the most accurate determination of the age of menarche marker be?
Through longitudinal analysis
How are most pubertal events initiated + regulated?
By the stimulation of ovaries + testes by gonadotropins (FSH + LH) secreted by the anterior pituitary + the elevated production of the sex steroids by the gonads.
Pros to Peak height velocity (PHV)
Non-invasive
Little training req
Reflects timing + magnitude of somatic maturation
Common benchmark within + between ind
Cons to PHV
Requires serial measures of stature + age
Only suitable for longitudinal studies
Computed retrospectively
What is the most common landmark of somatic maturity?
Age at peak height velocity (APHV)
Auxology
Understanding of the general principles of human growth, maturation + development.
When does a sudden increase in the velocity of the growth occur?
Pubertal period, second to the growth rate observed in the 1st yr of life.
What is meant by development?
The acquisition of behavioural competence
i.e learning the appropriate behaviours expected by society.
It’s culturally specific
What are the suggested techniques to be used for body size adjustments
Allometry + regression analysis
Advantage of longitudinal over cross-over sectional designs for controlling for the confounding effects of maturity
Within-ind variance can be obtained, meaning tempo + timing of an ind pattern of growth can be ID.
What could a pure longitudinal design look like?
Cohort of children born in the asme year are followed continuously for 3 or + years,
Why is longitudinal research often impractical for paediatric exercise research?
Process is laborious, expensive + time consuming for both participants + investigators.
What does the skeletal age assessment require?
X-ray of the hand + wrist or knee
What is the only method that spans the entire growth period?
Skeletal age assessment
How does the skeletal age assessment work?
Based on the observation that a person more advanced in maturity will have greater bone development + smaller amount of cartilage than a less mature person.
What is the most commonly used somatic milestone in longitudinal studies of childhood growth?
Age at Peak height velocity
How can the age when max velocity in statuary growth occurs be identified?
By plotting whole year height-velocity increments + curve-fitting procedures
At what biological age is a child at at the age of PHV?
Biological age of 0.0 from PHV.
What biological age from PHV will a child have if at 11.8 years they reach a PHV of 13.8yrs?
-2.0 yrs from PHV
PHV for early maturers
PHV is 1 year or more less than the mean age of PHV
PHV for late maturers
PHV is 1 year or more than the mean age of PHV
Predicting Age at PHV
What did Mirwald et al do?
Developed a gender-specific multiple regression equations based on segmental growth patterns to predict the maturity offset age parameter.
Allows for between-gender comparisons
What did Mirwald et al equations require?
Measures of:
- Stature
- Trunk length
- Leg length
- Body mass
- Chronological age
What are the 3 methods commonly used to establish age at menarche?
Prospective
Status quo
Recall - simple questionnaire
What does the status quo method for menarcheal status involve?
Large number of girls.
Birth date + whether they’ve started their menstrual flow.
== Calculate mean + SD for age of menarche
What did 1study find about the correlation coefficient between skeletal age + age at PHV?
0.83
The strength + direction of this indicates a maturity commonality between the 2 methods.
