BODY COMPOSITION
Understanding & Interpreting Body Composition Measures Body composition = component of health-related fitness & = component of metabolic fitness Unlike other health-related fitness Not a performance measure No movement/performance is required Good Metabolic Fitness: Blood lipid levels BP Blood glucose Insulin levels Concepts of Physical Fitness 14e 3
Body Composition Measures Standards have been established for healthy levels of body fatness Too Low Borderline Good Fitness Marginal Male 5 or less 6-9 10-20 21-25 26+ At Risk Female 10 or less 11-16 17-28 29-35 36+ Concepts of Physical Fitness 14e 4
Lipid Functions Temperature regulation Shock absorption Regulation of essential body nutrients
Essential Fat Nonessential Fat Extra fat stored in body Min amount of fat necessary to be healthy Amenorrhea Absent / infrequent menstruation osteoporosis
Body Composition Measures (Cont) Health standards have been established for the Body Mass Index. Too Low Borderline Good Fitness Overweight Obesity 12 or less 13-16 17-25 26-30 30+ Concepts of Physical Fitness 14e 7
BMI
BMI does not detect differences in muscle & fat Individuals with high muscle mass may be overweight using BMI Muscle weighs more than fat!! BMI Limitations
Assessing body weight too frequently Can lead to incorrect information People vary in body weight from day-day even hour-hour!!! Short term changes in weight: water loss/water gain = Based on level of hydration Weigh once a week At the same time of day Concepts of Physical Fitness 14e 10
Methods Used to Assess Body Composition Dual-energy X-ray Absorptiometry (DXA) Underwater Weighing Bod Pod Skinfolds Bioelectric Impedance Analysis (BIA) Near-Infrared Interactance Anthropometry Concepts of Physical Fitness 14e 11
Dual-Energy X-ray Absorptiometry Gold standard measure of body composition X-ray technique Estimate body density (DXA) Can measure fat stored in different parts of the body Measure of choice for measuring bone mass Costly
Visceral Fat - DEXA
Underwater Weighing Person = weighed in air & underwater Difference in weight = assess levels of body fatness
Same principle as underwater weighing Uses air displacement Useful for special population Bod Pod
Bioelectric Impedance Analysis Based on measuring resistance to current flow Electrodes are placed on body Low doses of current are passed through skin Muscle = greater water content than fat better conductor & less resistance to current
Near-Infrared Interactance Use the absorption of light to estimate body fatness High standard of errors Not recommended
Girth measurements Chest, waist, abdomen, hip, bicep Inexpensive & practical Anthropometry
Skinfolds Measure subcutaneous fat One-half of the body s fat = located under skin Most common procedure in research
Concepts of Physical Fitness 14e 22
Other Diseases/Medical Complications Cancer risk Skin problems Impaired circulation Stroke Liver disease
Who Is More Fit & Healthy???
Physical Fitness: Protection From Health Risks of Obesity High levels of body fat does not increase disease risk if the individual has good metabolic fitness!!!!! Good Metabolic Fitness: Blood lipid levels BP Blood glucose Insulin levels
Fit Not Fat THUS, cardiovascular & metabolic fitness are good measurements of health rather than measuring fat
Regional Fat Deposition UPPER BODY ANDROID FAT VISCERAL FAT WAIST-TO-HIP INCREASE HEALTH RISK LOWER BODY GYNOID FAT SUBCUTANEOUS
Waist-to-Hip Ration Determine risk for disease associated with fat & weight distribution A high waist circumference relative to hip circumference yield a high ratio indicative of high visceral fat
Obesity: Multifactorial Disease Influenced by genetics & environment Genetic predispose a person to obesity IF exposed to certain environmental conditions Regular PA can overcome genetic predispositions to fatness
Somatotype (Body Type)
Set-Point Theory Body= programmed to be a certain weight/set-point If you deviate from this set-point body makes metabolic adjustments to return to normal
Set-Point Theory (Cont) Leptin Regulating Hormone Leptin= produced by adipose cells More fat the more leptin Increased levels: suppress appetite & increase metabolism Decreased levels: increase appetite & decrease metabolism Exercising help reset the set-point
Set-Point Theory (Cont) Body can accommodate a higher set-point Greater resistance to adopt to lower set-point Sensitivity to leptin is reduced among the obese set point increase
Basal Metabolic Rate Energy expenditure in rested state Amount of calories needed to maintain body to function under resting conditions BMR decreases with age with the loss of lean body mass Increasing muscle mass increases BMR Anaerobic exercise can increase resting energy expenditure
Creeping Obesity PA & BMR decreases with age Caloric intake decrease with age does not compensate for decreases in PA & BMR This increase in fatness over time = creeping obesity
Creeping Obesity Concepts of Physical Fitness 14e 37
Relationship Between PA & Body Composition Combination of regular PA and dietary restriction is the most effective means of losing body fat. Dieting alone weight loss = lean tissue Strength training can be effective in maintaining a desirable body composition Increase muscle mass expends more calories at rest IN OTHER WORDS. Higher BMR!! Concepts of Physical Fitness 14e 38
Target Zone - Body Fat Reduction Physical Activity Daily moderate PA; 3-6 days/wk vigorous PA Low-intensity aerobic exercise 55-70%HRR Diet Consistently and daily Modest caloric restriction Moderate meals 30-60 minutes Concepts of Physical Fitness 14e 39
Health Risks Associated with Excessively Low Body Fatness Anorexia Nervosa Bulimia Anorexia Athletica Female Athlete Triad Muscle Dysmorphia (males) Fear of Obesity Purging Disorder Concepts of Physical Fitness 14e 40
Females & Exercise/Sport Female Athlete Triad Combination of 3 conditions: 1. Energy availability (E intake - EE) 2. Amenorrhea 3. Osteoporosis Can have one, two, or all three conditions Anorexia Athletica Related to participation in sports emphasizing body leanness Characterized by excessive, obsessive exercise May lead to anorexia nervosa
Muscle Dysmorphia A person becomes obsessed with the idea that they are not muscular enough Hold delusions that they are "skinny" or "too small" even when they are not reverse anorexia nervosa
Fear of Obesity Common among achievement-oriented teenagers Impose self-restriction on caloric intake because they fear obesity Stunting of growth Delayed puberty Delayed sexual development Decreased physical attractiveness
Purging Disorder Purging without bingeing