© 2007 McGraw-Hill Higher Education. All rights reserved. Growth and Maturation Chapter 6

© 2007 McGraw-Hill Higher Education. All rights reserved. Objectives Describe techniques for measuring body length and stature across the human lifespan Describe techniques for measuring body weight in ambulatory and nonambulatory individuals Describe the anticipated changes in body weight across the human lifespan Describe techniques for measuring body length and stature Describe anticipated changes in body length and stature across the human life span Describe techniques for measuring body weight in ambulatory and nonambulatory individuals Describe anticipated changes in body weight across the human life span Calculate body mass index (BMI) and describe changes in BMI across the human life span Describe gender differences associated with “adolescent awkwardness” Describe techniques for measuring changes in body proportionsticipated changes in body weight across the human lifespan

© 2007 McGraw-Hill Higher Education. All rights reserved. Objectives Describe anticipated changes in proportional body growth for head length to total body length, head circumference, sitting height, shoulder and hip width, and physique classifications Describe the relationship between somatic body proportions and motor performance Describe instrumentation used to assess skeletal health Describe the normal course of skeletal development and the two mechanisms that operate in the development of bone postnatally Explain the role of exercise in development and maintenance of skeletal health Describe the difference between chronological age and developmental age and explain four methods for determining developmental age Explain the relationship between maturation (developmental age) and motor performance

© 2007 McGraw-Hill Higher Education. All rights reserved. Level of maturation can influence motor performance

© 2007 McGraw-Hill Higher Education. All rights reserved. Measuring Growth in Length and Stature Recumbent length is measured from birth until a child is able to stand –Measured from the vertex (highest point on skull) to the soles of the feet

© 2007 McGraw-Hill Higher Education. All rights reserved. Measuring Growth in Length and Stature Stature or standing height is measured between the vertex and the floor Preferred measurement of body length

© 2007 McGraw-Hill Higher Education. All rights reserved. Measuring Growth in Length and Stature Stature can be estimated in the elderly and/or disabled populations from recumbent knee height

© 2007 McGraw-Hill Higher Education. All rights reserved. Calculation of Stature from Knee Height Stature Men – (0.04 x age) + (2.02 x knee height) Stature Women – (0.24 x age) + (1.83 x knee height)

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Length and Stature Zygote ~ 0.14 mm in diameter Birth –Boys ~ 20 in –Girls ~ in Year 1 –Boys ~ 30 in –Girls ~ in

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Length and Stature Year 2 –Length increases about 4.75 in Year 3-5 –Decelerated growth rate to 2.75 in/year Year 6-adolescence –Decelerated growth rate to 2.25 in/year Midgrowth spurt in height –Between 6.5 and 8.5 years –More common in girls

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Length and Stature Adolescence –20% of adult stature is attained during this 2 ½ to 3 year period –4 in /yr growth for boys –3 in/yr growth for girls 17.3 years –Median age in females when growth in stature ceases

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Length and Stature 21.2 years –Median age in males when growth in stature ceases –Females attain final 2% of growth in stature years –Growth of vertebral column may add another 1/8 in to stature years –Stature is stable

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Length and Stature Above 45 years ~ decrease in stature –Intervertebral disk degeneration –Joint cartilage in lower extremities becomes thin

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Length and Stature Plots accumulative growth over time Typical distance curve for stature

National Center for Health Statistics growth velocity charts for girls on variable stature Plots increments of change per unit of time Can determine periods of fast and slow growth

Stature-for-Age

Stature-for-Age Percentiles Use these charts to determine if an individual is growing normally

© 2007 McGraw-Hill Higher Education. All rights reserved. Measuring Body Weight Electronic digital scales, calibrated in metric units are recommended Chair scales are available for those who are not capable of standing

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Body Weight Conception ~ ovum weighs mg Median Birth Weight –Boys ~ 7.5 lb –Girls ~ 7.0 lb –Day 1-3 postnatal, infant may lose up to 10% of body weight Year 1 –Boys ~ 22.5 lb –Girls ~ 21 lb

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Body Weight Year 2 ~ gain of 5.5 lb Years 3-5 ~ gain of 4.5 lb Year 6 – Adolescence –Slight increase in rate of weight gain of 6.5/year Adolescence –Males add about 45 lb of body weight –Females add about 35 lb of body weight

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Body Weight Peak weight velocity = maximum rate of growth in body weight –Occurs after peak height velocity Mature body weight is approximately 20x that of birth weight

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Body Weight Year 18 –Males ~ lb –Females ~ lb Above 19 years –Weight is a matter of nutritional and exercise status –Some weight gain during pregnancy is permanent

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Body Weight Women with children tend to weigh more than childless sisters Some weight gain in pregnancy may be permanent Women who gain more weight than recommended may be at risk for obesity 10 yrs later

© 2007 McGraw-Hill Higher Education. All rights reserved. Growth in Body Weight Typical distance curve for body weight

National Center for Health Statistics growth velocity charts for boys and girls on variable body weight

© 2007 McGraw-Hill Higher Education. All rights reserved. Body Mass Index (BMI) Calculating BMI Healthy adult = Underweight = <18.5 Overweight = Obese = >30

© 2007 McGraw-Hill Higher Education. All rights reserved. Mary is a 46-year-old woman who weighs 132 pounds and is 65 in. tall. Calculate Mary’s BMI. Is Mary overweight?

© 2007 McGraw-Hill Higher Education. All rights reserved. Solution

© 2007 McGraw-Hill Higher Education. All rights reserved. BMI Chart Is Mary overweight? NO, her BMI is normal <18.5 = underweight = normal weight = overweight >30 = obese

© 2007 McGraw-Hill Higher Education. All rights reserved. BMI-for-Age In children and adolescents, BMI-for-age is best used as a guide to determine individual nutritional status BMI-for-age between 85 th percentile and 95 th percentile is classified as risk for becoming overweight BMI-for-age greater than 95 th percentile, overweight is a concern

© 2007 McGraw-Hill Higher Education. All rights reserved. BMI-for-Age Adiposity rebound: upward trend occurring after the low point on the BMI percentile curve –The earlier the adiposity rebound occurs in a child, the more likely BMI will be high in adulthood

© 2007 McGraw-Hill Higher Education. All rights reserved. BMI-for-Age NHANES, between 1960 and 2000 –Children and adults are fatter In adults –Mean height has increased 1 in –Mean body weight has increased 24 lb! In children –6-11 yr, both boys and girls are 9 lb heavier –12-17 yr, boys are 15 lb heavier and girls are 12 lb heavier

© 2007 McGraw-Hill Higher Education. All rights reserved. Stature and Weight: Motor Performance The interrelationship between weight and height is task specific during adolescence and adulthood Increased body weight is an asset in some sports Increased body fat exerts a negative influence on performance in sports where the body needs to be supported

© 2007 McGraw-Hill Higher Education. All rights reserved. Stature and Weight: Motor Performance On average –Thin, muscular, and small-boned babies walk earlier –Infants who are long for their weight walk earlier Motor performance may be delayed in obese infants –Most children catch up to peers within a year

© 2007 McGraw-Hill Higher Education. All rights reserved. Adolescent Awkwardness This refers to a period during the growth spurt where motor performance is disrupted –Peak height velocity Estimated age for boys = 13.7 yr –Most common in best performers at start of peak height velocity Estimated age for girls = 11.8 yr The phenomenon is not universal

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Head Circumference Ratio of head size to overall body length –Head contributes 25% to body length Head circumference –Indicative of brain development

Measuring Head Circumference

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Head Circumference Birth – head is ¼ of total body length –Head circumference is greater than chest circumference –Head circumference ~ 35 cm By year 1, head circumference increases 12 cm Year 2, head circumferences increases 5 cm Between ages 3 and 20 yr, head circumference only increases 5-6 cm

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Sitting Height Birth – sitting height = 85% of total length Age 6 – sitting height = 55% of total length Adult – sitting height = 50% of total length

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Stature 55-60% of stature increase due to leg growth Ratio between sitting height and stature –Describes the contribution of the legs and trunk to total height

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Body Proportions Sitting height/stature ratio

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Body Configuration Changes in body proportions with age Notice the great changes in the relative size of the head and lower limbs

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Shoulder and Hip Width Ratio between biacromial and bicristal breadths –Shoulder width to hip width

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Shoulder and Hip Width Mean biacromial and bicristal breadth Males – wide at shoulders Females – wide at hips

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in Shoulder and Hip Width % Bicristal/biacromial breadth x 100

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in the Center of Gravity A child’s center of gravity varies greatly because the head, trunk, and legs do not grow proportionally The center of gravity is high in children because a large proportion of their weight is in the upper body –Affects stability

© 2007 McGraw-Hill Higher Education. All rights reserved. Changes in the Center of Gravity For the adult, the center of gravity to total height is 53-59% –Males have a higher center of gravity than females do –Center of gravity is associated with the center of mass Men – chest Women – hips

© 2007 McGraw-Hill Higher Education. All rights reserved. Physique Overall body form W.H. Sheldon (1940) rated physique by three components –Endomorphic (round) –Mesomorphic (muscle) –Ectomorphic (thin)

© 2007 McGraw-Hill Higher Education. All rights reserved. EndomorphMesomorphEctomorph

© 2007 McGraw-Hill Higher Education. All rights reserved. Physique Heath and Carter (1967) Somatotype –Modified Sheldon’s method by adding anthropometry –Rating form includes measurement of skinfolds (endomorphic), height, breadth of bone, arm and calf circumferences (mesomorphic), and a ponderal index (ectomorphic)

© 2007 McGraw-Hill Higher Education. All rights reserved. Physique –Ponderal index = a way of characterizing height to mass –Typical numbers are in adults

© 2007 McGraw-Hill Higher Education. All rights reserved. Heath-Carter Somatotype

© 2007 McGraw-Hill Higher Education. All rights reserved. Body Proportion and Motor Performance Stability (balance) is a problem for young children due to their higher center of gravity and small base of support Balance is superior in women and girls due to their shorter legs and wider pelvis –Lowers center of gravity

© 2007 McGraw-Hill Higher Education. All rights reserved. Body Proportion and Motor Performance Wide hips, short legs, and a low center of gravity make running and jumping tasks difficult for girls Wider shoulders and longer arms in boys and men is an advantage for throwing events

© 2007 McGraw-Hill Higher Education. All rights reserved. Measuring Skeletal Health Dual-energy X-ray absorptiometry (DEXA) –Can measure differences among lean soft tissue, fat soft tissue, and bone tissue –Determines BMD – bone mineral density US is an aging society –More concern for bone diseases like osteoporosis

© 2007 McGraw-Hill Higher Education. All rights reserved. DEXA ~ Dual-Energy X-ray Apsorptiometry

© 2007 McGraw-Hill Higher Education. All rights reserved. DEXA ~ Bone Mineral Density Results

© 2007 McGraw-Hill Higher Education. All rights reserved. (a) Normal Bone (b) Osteoporotic Bone

© 2007 McGraw-Hill Higher Education. All rights reserved. Skeletal Development Appositional growth –Long bones grow in width by bone apposition on the outer surface of the bone –Short, flat, and irregular bones increase size by this method Endochondral growth –Involves the interstitial growth of cartilage followed by calcification of this cartilage –The result is increased bone length

© 2007 McGraw-Hill Higher Education. All rights reserved. Skeletal Development In utero –Intramembranous bone formation Embryonic membranes begin to ossify All long bones begin to ossify by birth Bone remodeling –Occurs throughout the lifespan –Osteoblasts (building) –Osteoclasts (chewing)

© 2007 McGraw-Hill Higher Education. All rights reserved. Skeletal Development From birth to 35 yr – osteoblast activity > osteoclast activity –Gaining bone After 35 yr, osteoclast activity > osteoblast activity –Exercise and stress on the bones becomes important

© 2007 McGraw-Hill Higher Education. All rights reserved. Skeletal Development Endochondral growth occurs at the epiphyseal plate (growth plate) Bone growth in length occurs when the epiphyseal plate becomes ossified and forms the epiphyseal line –Osteoblastic (bone building cell) activity

© 2007 McGraw-Hill Higher Education. All rights reserved. Exercise and Skeletal Health Interaction among activity, nutrition, genetics, and lifestyle Exercise increases bone density Inactivity is associated with bone decalcification (bone loss) Long periods in space reduce bone mass unless a vigorous exercise program is followed (treadmill)

© 2007 McGraw-Hill Higher Education. All rights reserved. Exercise and Skeletal Health Female athlete triad –Amenorrhea –Eating disorders –Bone mineral loss These problems are interrelated and this interrelationship is not completely understood in young women athletes

© 2007 McGraw-Hill Higher Education. All rights reserved. Female Athlete Triad - Interrelationships Eating Disorder Restrictive dieting Overexercising Loss of weight Bone Mineral Loss Osteoporosis Amenorrhea Diminished hormones

© 2007 McGraw-Hill Higher Education. All rights reserved. Maturation & Developmental Age Chronological age –Often used to denote maturity, but is a poor indicator Developmental age –Much better indicator of maturity –e.g., adolescence –Addresses variations in rate of maturation

© 2007 McGraw-Hill Higher Education. All rights reserved. Skeletal Maturity 3-year-old 5-year-old 14-year-old

© 2007 McGraw-Hill Higher Education. All rights reserved. Dental Maturity Dental maturation –Count the number of teeth that have emerged Dental age –Radiographs determine stage of bone calcification –Technique of choice –Can compare developmental stages

© 2007 McGraw-Hill Higher Education. All rights reserved. Age of Menarche The onset of menstruation Mean age in developed countries is 13.2 yr –Often occurs earlier in American girls Signifies uterine maturity, not reproductive maturity

© 2007 McGraw-Hill Higher Education. All rights reserved. Age of Menarche To determine the age of menarche ask questions –Do you know what menstruation means? –Have you already menstruated? –Can you remember the exact date of your first menstruation? –What grade were you in? –Was the event close to you birthday?

© 2007 McGraw-Hill Higher Education. All rights reserved. Genitalia Maturity Stages of pubertal development Girls –Assess pubic hair and breast development Boys –Assess pubic hair and reproductive organ development

© 2007 McGraw-Hill Higher Education. All rights reserved. Maturation and Motor Performance The level of maturation can affect motor performance Postpubescent boys initially outperform prepubescent boys Once the late-maturing boys reach adolescence, the advantage is no longer evident

© 2007 McGraw-Hill Higher Education. All rights reserved. Maturation and Motor Performance Early maturation in not associated with superior motor performance in girls, except in swimming Late-maturing girls have superior motor performance –Longer arms and legs –Narrower hips

© 2007 McGraw-Hill Higher Education. All rights reserved.