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© 2007 McGraw-Hill Higher Education. All rights reserved. Physiological Changes: Health Related Physical Fitness Chapter 7.

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1 © 2007 McGraw-Hill Higher Education. All rights reserved. Physiological Changes: Health Related Physical Fitness Chapter 7

2 © 2007 McGraw-Hill Higher Education. All rights reserved. Objectives Describe how the components of cardiovascular fitness change across the human life span and how these changes are influenced by increases in physical activity Describe the developmental changes in muscular strength/muscular endurance across the human life span and how these changes are influenced by maintaining an active lifestyle Describe the developmental changes in flexibility across the human life span and how these changes are influenced by participating in a flexibility training program

3 © 2007 McGraw-Hill Higher Education. All rights reserved. Objectives Describe the developmental changes in adipose tissue across the human life span, explain the prevalence of overweight and obesity, and identify the influence of being overweight or obese on both motor development and motor performance Identify gender differences in each component of health-related physical fitness Describe factors associated with physiological fitness Identify several points of controversy and concern regarding health-related physical fitness across the human life span

4 © 2007 McGraw-Hill Higher Education. All rights reserved. Maintaining an active lifestyle is linked to good health

5 © 2007 McGraw-Hill Higher Education. All rights reserved. Are children and adults less active today? Are children and adults more overweight/ obese today? Is there a physical activity ~ health link? Fitness components: 1.Cardiovascular endurance 2.Body composition 3.Flexibility 4.Muscular strength and endurance

6 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness A form of muscular enduranceA form of muscular endurance Efficiency of the heart, lungs, and vascular system in delivering oxygen to working tissueEfficiency of the heart, lungs, and vascular system in delivering oxygen to working tissue The body’s ability to deliver oxygen to the muscle is affected byThe body’s ability to deliver oxygen to the muscle is affected by –Heart rate –Stroke volume –Cardiac output –Maximal oxygen consumption

7 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Heart Rate (HR) The number of times the heart beats each minute (bpm)The number of times the heart beats each minute (bpm) Changes over the lifespanChanges over the lifespan –Fetal HR is rapid and irregular –Birth HR is below fetal level with periods of bradycardia (HR < 60 bpm) bpm bpm

8 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Heart Rate Children's HRChildren's HR –1 year ~ bpm –HR will continue to decline at rest until adolescence AdolescenceAdolescence –Male ~ bpm –Female ~ bpm

9 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Heart Rate Overall, resting HR declines by 50% from birth to maturityOverall, resting HR declines by 50% from birth to maturity AdulthoodAdulthood –Average ~ bpm There is a decline in HR with age –Researchers believe the decline in HR with age is due to a decrease in myocardial (heart) sensitivity to catecholamines, prolonged diastolic filling time, and changes in the contractile properties of cardiac muscle

10 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Heart Rate Maximal HR declines with maturityMaximal HR declines with maturity To predict maximal HRTo predict maximal HR –220-age = HR max –HR max = bpm –Decline = 0.8 bpm/year of age

11 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Heart Rate To predict maximal HR in the elderlyTo predict maximal HR in the elderly –HR max = 208 – 0.7(age in yr) Calculate the predicted HR of a 70-year-old male HRmax = 208-(0.7x70) HRmax = 159 bpm

12 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Heart Rate Work and HRWork and HR –Linear relationship –As workload increases, HR increases Workload HR

13 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Stroke Volume (SV) The volume of blood ejected from the heart with each beat (ml/beat)The volume of blood ejected from the heart with each beat (ml/beat) Size of SV affected bySize of SV affected by –Heart size –Contractile force of the heart muscle –Vascular resistance to blood flow –Venous return

14 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Stroke Volume SV is lower in childrenSV is lower in children –Due to smaller heart Lifespan changesLifespan changes –Birth ~ 3-4 ml/beat –Adolescence ~ 40 ml/beat –Male adult ~ ml/beat –Trained male adult ~ ml/beat

15 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Stroke Volume Maximal stroke volume is achieved during submaximal workMaximal stroke volume is achieved during submaximal work SV Workload 40-60% (O 2 max)

16 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Stroke Volume Maximal SV during exerciseMaximal SV during exercise –Untrained male ~ ml/beat –Untrained female ~ ml/beat –Trained male ~ ml/beat –Trained female ~ ml/beat Differences between male and female values due to smaller heart in female (25%)Differences between male and female values due to smaller heart in female (25%)

17 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Stroke Volume Stroke volume and ageStroke volume and age –Between the ages of yr, SV can fall by 30% Lifespan activity can minimize the SV decline with ageLifespan activity can minimize the SV decline with age

18 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Cardiac Output Amount of blood pumped in 1 minuteAmount of blood pumped in 1 minute HR x SV = CO or Q (flow)HR x SV = CO or Q (flow) At rest, CO equals ~5 liters/minAt rest, CO equals ~5 liters/min –70 beats/min x 70 ml/beat = 4900 ml/min or 4.9 liters/min

19 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Cardiac Output CO and exerciseCO and exercise –Affected by physical condition –Age Untrained male ~ liters/minUntrained male ~ liters/min Trained male ~ liters/minTrained male ~ liters/min Because HR and SV decline with age, so does COBecause HR and SV decline with age, so does CO –Decline of 1 % / year after age 25

20 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Maximal Oxygen Consumption The largest amount of oxygen that a human can utilize at the tissue level (VO 2 max )The largest amount of oxygen that a human can utilize at the tissue level (VO 2 max ) This is the best measure of physical work capacity (ability to do work without fatigue)This is the best measure of physical work capacity (ability to do work without fatigue) Very little data exist on children under 6 years of ageVery little data exist on children under 6 years of age

21 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Maximal Oxygen Consumption For boys ages 6 to 16 years, VO 2 max 50 to 53 ml/kg/minFor boys ages 6 to 16 years, VO 2 max 50 to 53 ml/kg/min For girls at 8 yr, VO 2 max = 50 ml/kg/min, on averageFor girls at 8 yr, VO 2 max = 50 ml/kg/min, on average Must correct for weight (kg), so boys/men can be compared with girls/womenMust correct for weight (kg), so boys/men can be compared with girls/women

22 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Maximal Oxygen Consumption There is a gradual decline in maximal oxygen consumption in young girls as maturity approaches due toThere is a gradual decline in maximal oxygen consumption in young girls as maturity approaches due to –Increases in body fat –Lower blood hemoglobin concentrations –A decline in large muscle development Many girls become less active during adolescenceMany girls become less active during adolescence

23 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Fitness: Maximal Oxygen Consumption With age there is a decline in VO 2 max and a concomitant decline in physical work capacityWith age there is a decline in VO 2 max and a concomitant decline in physical work capacity –Rate of decline is 1% per year An active lifestyle across the lifespan can alter this declineAn active lifestyle across the lifespan can alter this decline

24 © 2007 McGraw-Hill Higher Education. All rights reserved. Physical Activity and Cardiovascular Fitness in Childhood Information is fragmented and limitedInformation is fragmented and limited Are changes in the cardiovascular values in children due to training or maturation?Are changes in the cardiovascular values in children due to training or maturation? Some researchers question the value of endurance training in preadolescent childrenSome researchers question the value of endurance training in preadolescent children –Some will argue that training will improve performance

25 © 2007 McGraw-Hill Higher Education. All rights reserved. Physical Activity and Cardiovascular Fitness in Childhood VO 2 max changes in children are small to moderateVO 2 max changes in children are small to moderate Prepubertal children can follow the standard prescription used by adultsPrepubertal children can follow the standard prescription used by adults –Frequency = 3 days per week –Intensity = 60%-80% HR max –Time = min

26 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Endurance Field-Test Data Field test data involve non-laboratory devices capable of testing large numbers of childrenField test data involve non-laboratory devices capable of testing large numbers of children –Practical –Inexpensive Most popular field test for childrenMost popular field test for children –Timed distance run

27 © 2007 McGraw-Hill Higher Education. All rights reserved. Cardiovascular Endurance Field-Test Data Boys’ run time peaks at 16 yrBoys’ run time peaks at 16 yr Girls’ run time peaks at 14 yrGirls’ run time peaks at 14 yr On average, boys run faster than girls at all ages

28 © 2007 McGraw-Hill Higher Education. All rights reserved. Physical Activity and Cardiovascular Fitness in Adulthood Prescription ~ FITPrescription ~ FIT –Frequency = 3 to 5 days/week –Intensity = 60-90% HR max –Time = min Mode of activity is any large muscle group movement (walking, biking, running)Mode of activity is any large muscle group movement (walking, biking, running) A program of this sort will increase physical working capacityA program of this sort will increase physical working capacity

29 © 2007 McGraw-Hill Higher Education. All rights reserved. Physical Activity and Cardiovascular Fitness in Adulthood Physiological changes during submaximal workPhysiological changes during submaximal work –SV will increase –HR will decrease –CO will increase –HR recovery is quicker –Therefore, work is easier after training

30 © 2007 McGraw-Hill Higher Education. All rights reserved. Physical Activity and Cardiovascular Fitness in Adulthood It has been suggested that as much as 50% of the functional declines in the factors affecting physical performance are due to disuse and not agingIt has been suggested that as much as 50% of the functional declines in the factors affecting physical performance are due to disuse and not aging What effect does a physical exercise training program have on physical work capacities of elderly people?What effect does a physical exercise training program have on physical work capacities of elderly people?

31 © 2007 McGraw-Hill Higher Education. All rights reserved. Physical Activity and Cardiovascular Fitness in Adulthood If an older individual can improve VO 2 max by 20%, that is like 20 years of rejuvenation!If an older individual can improve VO 2 max by 20%, that is like 20 years of rejuvenation!

32 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Minimal muscular strength is important for human movementMinimal muscular strength is important for human movement How much strength does a toddler need to walk?How much strength does a toddler need to walk? How much strength does it take for an elderly individual to get up from a chair?How much strength does it take for an elderly individual to get up from a chair? Lacking minimal strength can limit an individual's freedom of movementLacking minimal strength can limit an individual's freedom of movement

33 © 2007 McGraw-Hill Higher Education. All rights reserved. Defining and Measuring Muscular Strength Strength is the ability to exert a muscular forceStrength is the ability to exert a muscular force Static or isometric force – muscular force exerted against a non-moveable objectStatic or isometric force – muscular force exerted against a non-moveable object Dynamic force – muscular force exerted against a moveable objectDynamic force – muscular force exerted against a moveable object

34 © 2007 McGraw-Hill Higher Education. All rights reserved. Defining and Measuring Muscular Strength Laboratory testLaboratory test –Grip strength Field testsField tests –Pull-up test ~ upper body strength/endurance –Chin-up test ~ upper arm strength/endurance –Modified bent-knee sit-up test ~ abdominal strength/endurance

35 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Laboratory Tests Grip strength test is a common test among childrenGrip strength test is a common test among children –Easy to administer –Reliable Changes in strength are tied to changes in body weightChanges in strength are tied to changes in body weight

36 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Laboratory Tests In boys, the strength “spurt” lags a year behind the height “spurt”In boys, the strength “spurt” lags a year behind the height “spurt” –Boys tend to outgrow their strength just prior to puberty –May explain why some boys experience a period of clumsiness Boys’ fastest increase in muscular strength occurs 1 yr after peak height velocityBoys’ fastest increase in muscular strength occurs 1 yr after peak height velocity

37 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Laboratory Tests In girls, the strength spurt occurs during the same year as peak height velocityIn girls, the strength spurt occurs during the same year as peak height velocity In general, boys are 10% stronger than girlsIn general, boys are 10% stronger than girls Gender differences are most apparent after pubertyGender differences are most apparent after puberty –Total body strength in women is 63.5% of men –Absolute upper-body strength in women is 50% less than men –Absolute lower-body strength in women is 20-30% lower than men

38 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Laboratory Tests AgingAging –Between yr there is a slow loss in muscle mass of about 10% –Between yr there is an accelerated loss of muscle mass of about 40% –Therefore, one can lose approximately 50% of total muscle mass by the age of 80 yr

39 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Field Tests Bent-knee sit-upsBent-knee sit-ups –60s time limit –Reflects ratio of abdominal strength/endurance to upper- body mass Modified pull-up (chin-up)Modified pull-up (chin-up) –Reflects ratio of upper body strength/endurance to total body mass Body mass is a confounding factor in these field testsBody mass is a confounding factor in these field tests

40 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Field Tests Average scores for boys and girls on bent-knee sit-ups (60 sec) based on findings of the National Children and Youth Fitness Studies I and II

41 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Field Tests Average scores for boys and girls on modified pull-ups and chin-ups based on findings of the National Children and Youth Fitness Studies I and II

42 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Field Tests Abdominal strength/enduranceAbdominal strength/endurance –Little differences exist between boys and girls ages 6 to 9 yr –After age 10 yr, boys outperform girls –Performance for both boys and girls levels off between 16 to 18 yr

43 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Field Tests Upper-body strength/enduranceUpper-body strength/endurance –30% of boys age yr failed to perform 1 chin-up during the NCYFS I –Modified pull-up test developed for the NCYFS II Modified Pull-up Test

44 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-related Changes in Muscular Strength: Field Tests Upper-body strength/enduranceUpper-body strength/endurance –Little differences exist between boys and girls ages 6 to 9 yr –After age 10 yr, boys outperform girls –After age 10 yr, girls are not capable of performing any chin-ups

45 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training PrepubescentPrepubescent –Controversy exists regarding strength training for this population –Can children increase strength through a resistance training program? –Can these strength gains improve athletic performance? –How does strength training affect flexibility, blood pressure, anaerobic fitness, and body composition?

46 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Prepubescent individuals are capable of significantly increasing strength following a resistance training programPrepubescent individuals are capable of significantly increasing strength following a resistance training program Are these gains in strength accompanied by gains in performance?Are these gains in strength accompanied by gains in performance?

47 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training PrepubescentPrepubescent –Skills showing improvement Long jumpLong jump Vertical jumpVertical jump Running speedRunning speed AgilityAgility –Specificity ~ greatest skill improvement was for those activities in which the children were involved

48 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training PrepubescentPrepubescent –Professional organizations publishing position statements for prepubescent strength training American Academy of PediatricsAmerican Academy of Pediatrics National Strength and Conditioning AssociationNational Strength and Conditioning Association American College of Sports MedicineAmerican College of Sports Medicine –All recognize the value of weight training

49 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training PrepubescentPrepubescent –Weight training involves the use of various resistance exercises to increase muscular strength, endurance, and power for fitness or sport –Weight/power lifting is a sport incorporating maximal lifts Not recommended for youth until physically mature (Tanner Stage 5)Not recommended for youth until physically mature (Tanner Stage 5) –Body building is a competitive sport Muscle size, symmetry, and definition are importantMuscle size, symmetry, and definition are important

50 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training PrepubescentPrepubescent –1 RM (repetition maximum) in boys and girls ages yr is safe when conducted in the presence of adult supervision

51 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Adolescence/early and middle adulthoodAdolescence/early and middle adulthood –Programs of progressive resistance training will result in improved muscular strength/endurance –Concerns for these populations Valsalva Maneuver ~ breath holding (straining) during a liftValsalva Maneuver ~ breath holding (straining) during a lift Anabolic steroid useAnabolic steroid use –Averages 4-6% among high school males –Averages 1-2% among high school females

52 © 2007 McGraw-Hill Higher Education. All rights reserved. Potential Adverse Effects of Anabolic Steroids MalesFemales Males & Females Baldness Prostate changes Gynecomastia Impotence/sterility Breast shrinkage Clitoral enlargement Increased facial/body hair Menstrual irregularities Premature hair loss Deepened voice Acne Aggression Brittle connective tissue Cardiovascular disease Cerebrovascular incidents Dependency Headaches Hypertension Liver disease Psyche and behavior changes Short stature (premature epiphyseal closure)

53 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Minimal training standards (ACSM)Minimal training standards (ACSM) –Frequency ~ 2 times per week –Intensity ~ 60% of 1 repetition maximum –Amount ~ 1 set 1 set of 8 to 12 exercises1 set of 8 to 12 exercises 8-10 repetitions per exercise8-10 repetitions per exercise

54 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Late adulthood –Can strength training in late adulthood alter, delay, or allow one to avoid the physiological deterioration associated with aging? –Even though decreases in muscular strength can be expected with age, the rate of decline can be significantly slowed Getty Images

55 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Late adulthoodLate adulthood –It is never too late to start a resistance-training program 1.9% to 132% improvements in strength1.9% to 132% improvements in strength –For the elderly, it is the intensity of the training and not the initial level of fitness that determines the response to training

56 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Late adulthoodLate adulthood –Strength training also decreases the number of falls experienced by this population –Strength training positively influences activities of daily living Improved walking speedImproved walking speed Improved functional index of mobilityImproved functional index of mobility

57 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Mechanisms of strength increaseMechanisms of strength increase –In the early phase of training, neural adaptation predominates Most training studies incorporate this phaseMost training studies incorporate this phase –In intermediate and advanced training, progress is limited to the extent of muscular adaptation that can be achieved HypertrophyHypertrophy Anabolic steroid useAnabolic steroid use

58 See text for full description

59 © 2007 McGraw-Hill Higher Education. All rights reserved. Muscular Strength Training Prepubescent children do not gain muscle massPrepubescent children do not gain muscle mass Low level of circulating androgens, but does not provide a complete answer because young adult women can gain muscle massLow level of circulating androgens, but does not provide a complete answer because young adult women can gain muscle mass ElderlyElderly –Sarcopenia results in loss of muscle strength –With loss of strength and increase in frailty, falls are more common

60 © 2007 McGraw-Hill Higher Education. All rights reserved. Flexibility Range of motion with a jointRange of motion with a joint Flexibility is joint specificFlexibility is joint specific –There is no one good test for overall flexibility A typical flexibility testA typical flexibility test –Sit-and-reach test / back saver sit-and-reach test –Tests the hamstring, back and hip flexibility

61 © 2007 McGraw-Hill Higher Education. All rights reserved. Flexibility Sit and reach test Back saver sit and reach test Sit-and-reach-test Back saver sit-and-reach-test evaluates flexibility on one side at a time

62 © 2007 McGraw-Hill Higher Education. All rights reserved. Flexibility Average sit-and-reach scores for boys and girls based on finding of the National Children and Youth Fitness Studies I and II Peak flexibility occurs during late teens Girls attain better scores Performance Trends

63 © 2007 McGraw-Hill Higher Education. All rights reserved. Flexibility Flexibility declines with age due to changes inFlexibility declines with age due to changes in –Connective tissue (tendons, ligaments) ~ less resilient and may crack or fray –Synovial fluid ~ less viscous –Cartilage ~ may be damaged from injury or lifelong wear and tear –Osteoarthritis (joint disease)

64 © 2007 McGraw-Hill Higher Education. All rights reserved. Flexibility Declining flexibility and agingDeclining flexibility and aging –Osteoarthrosis is common in 80% of adults between the ages of 55 and 64 yr Regardless of process or causes, physical activity is necessary to maintain joint mobilityRegardless of process or causes, physical activity is necessary to maintain joint mobility

65 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Defining obesityDefining obesity –Three Popular Definitions: –Social: Many define obesity based upon appearance alone or the number of pounds one is “overweight” –Statistical: Based on estimates established from normative studies of population –Operational: Based on criteria tied to rates of Mortality and Morbidity – BMI a widely used operational measure –Body composition Amount of lean body tissue vs. fat tissueAmount of lean body tissue vs. fat tissue

66 © 2007 McGraw-Hill Higher Education. All rights reserved. Classifications Weight StatusBMIWaist Circumference Underweight<18.5 kg/m 2 Normal kg/m 2 Overweight kg/m 2 Obese>30 kg/m 2 >100cm

67 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Growth trends in adipose tissueGrowth trends in adipose tissue –Birth ~ 11% fat in boys and 14% in girls –Fat at birth is stored in ~5 billion adipocytes –The number of fat cells continues to increase in childhood –Body fat declines at the onset of walking

68 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Two growth spurts in fat tissueTwo growth spurts in fat tissue –1st yr: fat increase in boys ~26%; in girls ~28% –Puberty for boys; prepuberty and puberty for girls Greater fat mass in girls during the second growth spurtGreater fat mass in girls during the second growth spurt With age, fat’s contribution to overall body composition depends upon the size of fat cells, not the number of cellsWith age, fat’s contribution to overall body composition depends upon the size of fat cells, not the number of cells

69 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity General growth trendsGeneral growth trends –Body weight reaches its peak at about 45 years of age Body weight is not a good indicator of body compositionBody weight is not a good indicator of body composition A sedentary lifestyle lends to the observed decrease in lean body mass and an increase in fat massA sedentary lifestyle lends to the observed decrease in lean body mass and an increase in fat mass

70 © 2007 McGraw-Hill Higher Education. All rights reserved. Percent Body Fat Optimal HealthOptimal Fitness Men10-25%12-18% Women18-30%16-25%

71 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Prevalence of obesity in the US ~ agePrevalence of obesity in the US ~ age –Children 6-11 yr = 15% are overweight* –Adolescents yr = 15% are overweight* –Adults = 64% are either overweight or obese * NHANES

72 © 2007 McGraw-Hill Higher Education. All rights reserved. Percent % NHANES - Children Percent of Overweight Children %Adolescents at Two Time Periods

73 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Prevalence of obesity in the US ~ racePrevalence of obesity in the US ~ race –Mexican American and black non-Hispanic women exhibit higher rates of overweight and obesity compared non-Hispanic white women –Mexican American men exhibit higher rates of overweight and obesity compared to non-Hispanic blacks and non-Hispanic whites

74 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Prevalence of obesity in the US ~ incomePrevalence of obesity in the US ~ income –Low socioeconomic status (income < 130% of the poverty level –High socioeconomic status (income > 130% of the poverty level

75 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Prevalence of obesity in the US ~ incomePrevalence of obesity in the US ~ income –Men in both groups are likely to become overweight and obese –Women in low socioeconomic groups are more likely to become overweight or obese compared to women in high socioeconomic groups

76 © 2007 McGraw-Hill Higher Education. All rights reserved. Age-adjusted Prevalence of Overweight or Obesity

77 © 2007 McGraw-Hill Higher Education. All rights reserved. Obesity Nationwide Increasing Prevalence

78 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Health consequencesHealth consequences –High blood lipid levels –Elevated blood pressure –Diabetes –Cardiovascular disease

79 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Association between childhood and adulthood obesityAssociation between childhood and adulthood obesity –Children with a BMI value at the 95 th tile for their age and gender have a greater than 60% chance of being obese at age 35 yr Association between childhood and parental obesityAssociation between childhood and parental obesity –Parental obesity more than doubles the likelihood that a child will be obese in adulthood

80 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Selected percentiles for BMI in males from the Second National Health and Nutrition Examination Survey BMI = wt(kg)/ht(m 2 )

81 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Selected percentiles for BMI in females from the Second National Health and Nutrition Examination SurveySelected percentiles for BMI in females from the Second National Health and Nutrition Examination Survey BMI = wt(kg)/ht(m 2 )

82 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Field test measures of body fatField test measures of body fat –Hydrostatic weighing –Bod Pod –Dual energy X-ray absorptiometry (DEXA) –Skinfold calipers

83 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Hydrostatic Weighing Hydrostatic weighing has been the preferred method for determining percent body fatHydrostatic weighing has been the preferred method for determining percent body fat This test is not practical as a field-test measureThis test is not practical as a field-test measure Calculations based upon water displacementCalculations based upon water displacement

84 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Bod Pod The Bod Pod is quickly becoming the new standard in body composition measurementThe Bod Pod is quickly becoming the new standard in body composition measurement Calculations are based upon air displacementCalculations are based upon air displacement Everyone can be tested ~ disabled, children, elderlyEveryone can be tested ~ disabled, children, elderly

85 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Skinfolds Average sum of triceps and subscapular skinfold thicknesses in boys and girls

86 © 2007 McGraw-Hill Higher Education. All rights reserved. % Fat

87 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Obesity Relationship of obesity to motor development and performanceRelationship of obesity to motor development and performance –In general, greater amounts of fat are negatively related to activities where the body has to be projected or lifted (tests of vertical jumping, running/walking, running)

88 © 2007 McGraw-Hill Higher Education. All rights reserved. Body Composition ~ Treatment We Can ProgramWe Can Program –National Heart Lung Blood Institute –Aids parents and caregivers to help children (8-13 yr) to stay at a healthy weight

89 © 2007 McGraw-Hill Higher Education. All rights reserved. Gender Differences in Health-Related Physical Fitness During the ages of 4-18 yrDuring the ages of 4-18 yr –Strong negative correlation between BMI and endurance performance –Boys outperform girls in the distance run, chin-up, and sit-up tests –Girls outperform boys in the sit-and-reach test

90 © 2007 McGraw-Hill Higher Education. All rights reserved. Factors Associated with Physiological Fitness Children who perform well on tests of physiological fitness tend to participate in more community-based activities, watch less television, receive their physical education from a specialist, experience more activities over the course of a year, and come from families where physical activity is valued.

91 © 2007 McGraw-Hill Higher Education. All rights reserved. Points of Controversy and Concern Childhood health status is not associated with adult health statusChildhood health status is not associated with adult health status Athletic participation in youth is not associated with coronary risk factor status in middle ageAthletic participation in youth is not associated with coronary risk factor status in middle age

92 © 2007 McGraw-Hill Higher Education. All rights reserved. We are living longer. What is the best way to live a long and high quality life?

93 © 2007 McGraw-Hill Higher Education. All rights reserved.


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