1. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Chapter 11: Understanding and Improving Body Composition

2. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition Definitions –Absolute amount of fat & nonfat tissue in body –Ratio of fat to total body mass (TBM) Common Measures –Fat mass (FM): total mass of all fat in body –Fat-free mass (FFM): total mass of all nonfat tissues in body –Percent body fat (% fat): ratio of TBM to total FM

3. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Two individuals with the same TBM can have different body compositions.

4. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Obesity, Health, and Body Composition –Obesity is at epidemic proportions –Overweight: BMI = 25.0 to 29.9 –Obese: BMI ≥30 –In US: 300,000 people die each year from obesity-related diseases 65% of adults are either overweight or obese 31% are obese Prevalence of obesity is rapidly increasing

5. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Prevalence of obesity in US has drastically increased from 1995 to 2005.

6. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Diseases Associated With Obesity –Cardiovascular disease & atherosclerosis –Hypertension –Negative effects on blood lipid profile –Type 2 diabetes –Sleep apnea –Osteoarthritis –Complication in pregnancy & surgery –Cancer (uterine, kidney, colorectal, esophageal) –Gallbladder disease

7. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Causes of Obesity –Ingesting more calories than are expended (overeating) –Genetics (inability to produce leptin) –Alterations in appetite control –Physical inactivity –Cultural factors Abundance of high-calorie, high-fat food readily available Large portion sizes

8. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Physical Performance and Body Composition –Higher % fat or FM, but same FFM as another: Increased TBM to carry in physical activities, reducing performance Decreased relative peak oxygen consumption –Greater FFM is advantage in absolute strength measurements –Any correlation between body composition & physical performance task depends on: Measure of body composition Physical performance task examined

9. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Differences in body composition and body size based on sport demands.

10. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Body Size Versus Body Composition –Anthropometry: measurement & study of body size –Body size refers to: Total body mass Height or stature Body circumferences Bone breadths Limb lengths –Body size varies greatly between athletes of different sports & impacts performance in some sports & activities

11. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (cont’d) Body Mass Index (BMI) –Ratio of body mass divided by height –Used as a general indicator of health risks associated with: Obesity Severe underweight status % fat –Calculated by either of 2 equations: BMI (kg/m 2 ) = weight (kg)/height (m 2 ) BMI (kg/m 2 ) = weight (lb) × 703/height (in 2 )

12. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins BMI Classifications ClassificationBMI (kg/m 2 ) Underweight<18.5 Normal18.5−24.9 Overweight25.0−29.9 Obesity class I30.0−34.9 Obesity class II35.0−39.9 Obesity class III>40.0

13. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition Densitometry –Determination of body composition from body’s density –Body density = TBM/body volume –Determined by: Hydrostatic weighing (underwater weighing) Siri equation: % Fat (495/body density) − 450 –Body density varies with body composition –Assumptions involved in this method lead to some error

14. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Skinfolds –Pinching & measuring thickness of skin & subcutaneous fat –Performed at specific anatomical sites with special calipers –Convenient & widely used method –Measurements are used to predict body density –Body density is then used in an equation to predict % fat –Less accurate than hydrostatic weighing –Population-specific equations have been developed (men vs. women)

15. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Measurement of a skinfold using calipers.

16. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Air-Displacement Plethysmography –A densitometry technique using air displacement –Volume of air in empty chamber is known –Person enters chamber, displacing air –Volume of air left in chamber is determined –Body volume = air volume of empty chamber − air volume of occupied chamber –Body volume is used in equations to find body density & % fat –Generally as accurate as hydrostatic weighing, with some differences for specific populations

17. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Air-displacement plethysmography equipment.

18. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Bioelectrical Impedance –Electrodes are placed 2 or more spots on body –Electrical current is passed between them –Conductance is greater & impedance lower in FFM than in fat –FM, FFM, & total body water are calculated –Several types of equipment are available, with different accuracy –Generally as accurate as the other indirect methods

19. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Bioelectrical impedance.

20. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Dual-Energy X-Ray Absorptiometry (DEXA) –Uses low-energy x-ray beams & computer software to image body –Can determine general & regional body composition –Highly reliable –Sensitive to small changes in body composition –Significant correlations with hydrostatic weighing –Considered the “gold standard” in the measurement of body composition

21. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) DEXA method.

22. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Other Methodologies –Total body water measures –Nuclear magnetic resonance imaging (MRI) –Ultrasound

23. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) MRI.

24. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (cont’d) Ultrasound imaging.

25. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition Sex% body fat required by body % body fat of lean athletes % body fat of healthy non- athletes % body fat, unhealthy % body fat, obese Men3−56−1314−1718−25>25 Women12−1416−2021−2425−31>32

26. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Energy Balance –Ratio of caloric ingestion to caloric expenditure –Caloric expenditure > caloric ingestion = loss in body mass –Caloric expenditure < caloric ingestion = gain in body mass –Total caloric expenditure = resting metabolic rate (RMR) + caloric expenditure of physical activity –Changes in RMR affect total caloric expenditure & FM loss

27. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Dieting and Weight Loss Guidelines –Drink sufficient water –Make sensible fat choices –Minimize empty calories –Do not reduce calories too drastically –Keep portions small

28. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Effect of Exercise on Body Composition –Can decrease FM, if caloric expenditure > caloric ingestion –Can increase FFM –Can decrease % body fat due to either or both of the above –Estimating energy expenditure depends on many factors: Body mass Training intensity Which muscles are engaged # of sets & repetitions Length of rest periods

29. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Caloric Expenditure of Resistance and Aerobic Training –Caloric expenditure both during & after training must be measured –Weight & aerobic training sessions of equal length & intensity result in equivalent energy expenditure & fat metabolism –Both aerobic & weight training: Increase caloric expenditure during activity Increase resting energy expenditure up to 24−48 hrs after –Weight training offers advantage of increase in FFM & RMR –Combination of dieting & aerobic & weight training most effective

30. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Appetite and Exercise –Immediate effect of exercise: decrease in appetite –Decrease in appetite may occur due to: Elevated blood catecholamine concentrations Elevated body temperature Increased environmental temperatures Hormonal changes: ghrelin, leptin, insulin –Prolonged effect of exercise: overall increase in appetite, due to expenditure of calories

31. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Losing Body Mass Wisely –Goals Lose FM, not FFM Maintain loss once achieved –Must occur slowly, over time: 1 to 2 lb per week –Combination of diet & exercise –People respond differently to the same diet –150 to 400 kcal·day -1 should be expended in physical activity –Weight loss diet should supply between 1200 & 1600 kcal·day -1

32. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (cont’d) Mean % Fat –Typically lower than normal in athletes –Lower limits 5% for men 12% to 14% for women –Different techniques to measure body composition vary in results –Not all athletes will achieve optimal performance at low % fat –Body composition can vary greatly among athletes at different positions in the same sport

33. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Severe Weight Loss Dehydration –Results from rapid weight loss due to fasting, severe restriction –Glycogen is stored with water in body –Release of glycogen with metabolism releases body water –Dehydration of 3% to 4% of TBM decreases aerobic performance –Magnitude of effect on performance depends on the sport

34. Copyright © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Severe Weight Loss (cont’d) Female Athlete Triad –Syndrome consisting of 3 interrelated conditions affecting female athletes & active women: Menstrual cycle irregularities Osteoporosis Eating disorders: anorexia nervosa & bulimia nervosa –All relate to body composition & diet –Result in decreased performance & increased risk of injury –Athletes displaying signs should be referred for treatment