Chapter 3 Physical Development and Decline Age related changes in body dimension and composition do not stop I Changes in Body Shape A Anthropometry the branch of science dealing with the measurement of the human body obtain shape and compostion of the human body 1 Height 2 Weight 3 Breadths 4 Segment lengths 5 Circumferences B Height Changes 70 1 Distance from floor to the top of the head without shoes 2 Males peak height at 20 and decline slowly with loss of 4 by 70 Females peak height at 16 18 and decline slowly with loss of 3 by 3 In general men and women lose 1cm per decade in their 40 s and 50 s and then as they reach their 60 s and 70 s height loss is greater for women than men a Attributable to hormones diet weight physical activity and women s susceptibility to osteoporosis C Weight Changes 1 Obesity is a major concern in the United States a From 1964 1990 obesity has increased in all ages but most dramatically in women ages 20 29 Men have the largest increase in ages 50 59 year olds 2 Women s weight increases steadily until 45 50 then stabilizes until 70 3 Men s weight increases until 40 then plateau until 55 and then have a slow gradual decline in weight Explained by a Selective survival obese young and middle aged people die leaving individuals who have maintained their weight over time b Cohort effect older people come from cohorts where obesity was less common c Loss of weight after 65 is truly attributable to aging i Support indigenous populations have no increase in weight in middle age but decline at older ages still occurs 4 In the old old age group 80 there is a low prevalence of obesity a selective survival effect b attributable to the higher frequency of disease in this group 5 Involuntary weight loss occurs in 13 of 65 a 24 is unexplained but the rest is due to cancer depression GI ailments thyroid problems neurological problems response to medication Involuntary loss of weight is the single best predictor for risk of death in older adults II Body Mass Index A To calculate divide body weight kg by height m2 B Higher BMIs are positively associated with CV disease diabetes hypercholesterolemia hypertension and certain cancers C Not a direct measure of fatness or distribution of fat but a better measure than weight alone D Overweight BMI of 25 29 9 Obese BMI 30 a Mild 30 34 9 b Moderate 35 39 9 c Severe 40 E Location of fat is important large waist circumference is a better predictor of all cause mortality in non smokers than high BMI or high waist to hip ratios F Men decrease in BMI and weight after fifth decade primarily due to muscle loss significant decrease at 80 and 90 due to muscle and fat loss Women increase BMI through sixth decade decrease in BMI after 70 due to increase fat mass and decrease muscle mass a For both men and women there is little change in BMI from 25 55 G Lowest risk of death and disease a Men BMI between 23 5 and 24 9 b Women BMI between 23 and 23 4 H Problems with BMI a Overestimates fat in muscular individuals b Underestimate fat in those that have lost muscle mass older people c Persons with edema d Inaccurate in very short people III Changes in Body Composition Total body mass fat mass FM fat free mass FFM Fat free mass water protein and bone mineral A Body Fat organs a Essential Fat necessary for normal function of the CNS and other b Storage Fat fat stored in adipose tissue c The reference woman has more total fat than the reference man due to reproduction B Body Fat Distribution a Fat deposited in abdominal areas rather than hips and thighs are at an increase risk of disease b Android fat pattern male fat pattern beginning at age 9 men deposit more fat in the abdomen apple shaped c Gynoid fat pattern female fat pattern girls deposit more fat in the hips and legs pear shaped C Fat Mass Changes with Age a Most researchers have documented increases in body weight and FM through middle age and then stabilizing or declining after 60 b Body fat increases with age and is redistributed Intra abdominal fat increases and fat on limbs decreases i ii Younger women have lower intra abdominal fat than younger men but with age it increases until they are similar in their 7th decade 1 40 of the increase in intra abdominal fat occurs by the 5th decade c Metabolic syndrome constellation of risk factors including insulin resistance glucose intolerance abnormal lipoprotein lipid profiles and hypertension Abdominal obesity is the first step D Fat Free Mass Changes with Age a Muscle skin bone and organs includes essential fat b Also known as lean body mass c FFM peaks in 20s and 30s and then declines with age in both males and females i Primarily due to muscle atrophy d Loss of FFM is not well researched i Differences in cross sectional and longitudinal study conclusions e Muscle atrophy sarcopenia is as high as 40 in 80 and strongly associated with weakness disability and morbidity f Greatest risk of disability sarcopenic and obese this combination increases 2 in 60 69 and 10 in those 80 g Produced by exercise and changes in sex hormones or growth hormone levels E Exercise induced Adaptation in FM and FFM a Aerobic training is effective in reducing FM and greater amounts of FM is lost as sessions increased b Exercise effects on body fat distribution are different in men and women waist to hip ratios decrease in men but stay the same in women i Fat loss for men and women occurs preferentially in the central regions of the body c Aerobic exercise is not effective for increasing muscle mass d Resistance training also decreased FM 1 2 kg of FM while increasing FFM 1 1 2 1 kg i Energy needs during resistance training increased by 15 so increased food intake is necessary to stabilize weight e Elite athletes in the Masters category have lower body fat compared to others of their same age but 5 10 higher compared with younger athletes IV Changes in Bone A Bone Mineral Density BMD is best predictor of bone strength B Adult bone health is determined by peak bone mass and the rate of bone loss with age a Peak bone mass for women is 10 lower than that of men V Osteoporosis b 7 1 per year bone loss in men and women until 50 and the rate of bone loss increases in 8th and 9th decades in men and women c Bone loss in menopausal women is 2 3 per year women may lose 1 3 1 2 of BMD during menopause C Bone becomes more mineralized but also more porous so data shows the mineral content as lower than younger individuals A Osteoporosis characterized by low bone mass and