LWW PPT Slide Template Master

LWW PPT Slide Template Master

Chapter 11: Understanding and Improving Body Composition 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) Two individuals with the same TBM can have different body compositions. Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) Prevalence of obesity in US has drastically increased from 1995 to 2005.

Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Overview of Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) Differences in body composition and body size based on sport demands. Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Overview of Body Composition (contd) 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/m2) = weight (kg)/height (m2) BMI (kg/m2) = weight (lb) 703/height (in2) Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins BMI Classifications Classification BMI (kg/m2) Underweight <18.5 Normal

18.524.9 Overweight 25.029.9 Obesity class I 30.034.9 Obesity class II 35.039.9 Obesity class III >40.0 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Determining Body Composition Densitometry Determination of body composition from bodys 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) 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) Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) Measurement of a skinfold using calipers. Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Determining Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) Air-displacement plethysmography equipment. Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) Bioelectrical impedance. Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) DEXA method.

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

Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Determining Body Composition (contd) Ultrasound imaging. 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 nonathletes % body fat, unhealthy % body fat, obese Men 35 613 1417 1825

>25 1620 2124 2531 >32 Women 1214 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (contd) Dieting and Weight Loss Guidelines

Drink sufficient water Make sensible fat choices Minimize empty calories Do not reduce calories too drastically Keep portions small Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Changing Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (contd) 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 2448 hrs after

Weight training offers advantage of increase in FFM & RMR Combination of dieting & aerobic & weight training most effective Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (contd) 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 kcalday-1 should be expended in physical activity Weight loss diet should supply between 1200 & 1600 kcalday -1 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Changing Body Composition (contd) 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

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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins Severe Weight Loss (contd) 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 Copyright 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

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