KINE 2050 | CH.4 Book Notes PDF

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Summary

- Course: KINE 2050 (Quarter to Semester Fall 2020 Conversion)
- Cengage Required Book for course: Lifetime Physical Fitness & Wellness, 15th Edition
- Chapter Title: Body Composition
- Professor: Alex Dorado...

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KINE 2050 | Cengage CH.4 Book Notes | Body Composition Cengage CH.4 Book Notes | Chapter Introduction ➡ What constitutes ideal body weight? • There’s NO such thing as an ideal body weight. ! • Health and fitness professionals prefer to use the terms “recommended” or “healthy” body weight.

• The current recommended OR healthy weight standards (based on percent body fat, BMI, or waist-to-height ratio) are established at the point where there appears to be a lower incidence for overweight-related conditions for most people. !

➡ Most people manage their weight by using two sources of feedback—! • (1) the numbers on the scale ! • (2) & the way their clothing fits !

Cengage CH.4 Book Notes | Section 4.1 “What Is Body Composition?” ➡ What is Body Composition? ! • Body Composition - the fat & nonfat components of the human body; important in assessing recommended body weight. !

- Important to recognize that the human body consists of fat & nonfat components. !

• Percent Body Fat - proportional amount of fat in the body based on the person’s total weight; includes both essential fat & storage fat; also termed fat mass. !

- The fat component is called fat mass OR percent body fat ! 1

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• Lean Body Mass - body weight w/out body fat. ! - The nonfat component ! • Recommended Body Weight - body weight at which there seems to be NO harm to human health; healthy weight. !

- To determine, you need to find out ! ‣ what % of total body weight is fat ! ‣ & what amount is lean tissue. (AKA assess body composition)! - Body composition should be assessed by a well-trained technician who understands the procedure being used. !

- Once the fat percentage is known, recommended body weight can be calculated from recommended body fat. !

• Guidelines for recommended body weight, also called “healthy weight,” have been set at values where there are NO medical conditions that would improve w/ weight loss. !

- The guidelines take into consideration body shape (or fat distribution pattern) that’s NOT associated w/ higher risk for illness. !

➡ Types of Body Fat ! • Body fat is an endocrine organ—it responds to stimuli and releases hormones to communicate with the brain and body. !

➡ Essential & Storage Fat ! • Total fat in the human body is classified into essential fat & storage fat. ! • Essential Fat - minimal amount of body fat needed for normal physiological functions; constitutes about 3% of total weight in men & 12% in women. !

- Is needed for normal physiological function. ! - W/out it, human health & physical performance deteriorate. ! - This type of fat is found w/in tissues such as muscles, nerve cells, bone marrow, intestines, heart, liver, & lungs. !

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- The % is higher in women because it includes gender-specific fat, such as that found in the breast tissue, the uterus, & other related fat deposits. !

- Hoeger Key ! • Storage Fat - body fat in excess of essential fat; stored in adipose tissue. ! - Mostly just beneath the skin (subcutaneous fat) & around major organs in the body (visceral fat). !

- This fat performs 4 basic functions: ! ‣ (1) it stores calories to be mobilized when a person gets hungry, ! ‣ (2) it releases hormones that control metabolism, ! ‣ (3) it insulates the body to retain heat, ! ‣ (4) & it acts as padding against physical trauma to the body. ! - The amount of storage fat does not differ between men & women. ! ‣ Except that men tend to store fat around the waist & women around the hips & thighs. !

Cengage CH.4 Book Notes | Section 4.2 “Why Does Body Composition Matter” ➡ Why Does Body Composition Matter? !

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• Simple height/weight measurements provide important feedback. ! • By averaging data across large groups of individuals, scientists have been able to establish that the risk for premature illness & death is greater for those who are overweight & that the risk is also increased for individuals who are underweight. !

➡ High Body Weight Does Not Always Mean High Body Fat ! • Overweight - an excess amount of weight against a given standard, such as height or recommended % body fat. !

- Best way to determine whether people are truly overweight or falsely at recommended body weight is through assessment of body composition. !

• Obesity - an excessive accumulation of body fat, usually at least 30% greater than recommended body weight. !

- An excess of body fat. ! • Some athletes who appear to be 20 or 30 pounds overweight really have little body fat. !

➡ Low Body Weight Does Not Always Mean Low Body Fat ! • Some people who weigh very little (& may be viewed as skinny OR underweight) actually can be classified as overweight because of their high body fat content. !

• People who weigh as little as 120 pounds but are more than 30% fat (about 1/3 of their total body weight) are NOT RARE. !

- Found more readily in the sedentary population & among people who are always dieting. !

➡ Weight Loss vs. Fat Loss ! • Loss in overall body weight can include a combination of: ! - loss in water weight, ! - lean body mass, ! - muscle mass, ! - & body fat. !

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• Although individuals may lose overall body weight when dieting, the weight loss may not always include the desired loss of body fat, but rather the loss of lean body mass & muscle mass.%!

• Both physical inactivity & an ongoing negative caloric balance due to dieting can lead to a loss in lean body mass. !

• A loss in lean body mass results in a decrease in calories burned each day through the basal metabolic rate, among other adverse effects. !

- This loss of lean body mass can be offset OR eliminated, however, by combining a sensible diet with exercise. !

• By tracking body composition, dieters can identify fad diets that promote the loss of water & lean body mass, especially muscle mass. !

- Can opt instead for lifestyle changes that decrease body fat while maintaining OR increasing lean body mass. !

• As you begin to increase exercise & adopt a healthy nutrition plan, your body responds w/ the beneficial change of increasing muscle mass. !

• Muscle is heavier than fat ! ➡ Avoiding Creeping Changes in Body Composition ! • Trends indicate that adults in the United States gain one to two pounds per year. ! • Over a span of 40 years, the average American will have gained 40 to 80 pounds. !

• Because of the typical reduction in physical activity in our society, however, the average person also loses half a pound of lean tissue each year. !

• When it comes to the areas where that individual stores body fat (apples vs. pears), gender and genetics are in control.% !

• Women also have an increased tendency to store fat in the abdominal area following menopause. !

• An active individual who remains overweight will tend to store body fat as subcutaneous fat, whereas an inactive individual will tend to store it as the more risky visceral fat. !

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• When it comes to diet and disease risk, studies indicate that not all excess calories appear to end up in the same place. !

• %Food selections help determine where the fat ends up. ! • Saturated & trans fats, excessive calories from alcohol, & added sugars (such as sucrose, fructose, & high-fructose corn syrup), all tend to end up as visceral fat. !

• !

Cengage CH.4 Book Notes | Section 4.3 “Body Shape & Health Risk” ➡ Body Shape & Health Risk ! • A person’s total amount of body fat by itself is not the best predictor of increased risk for disease but, rather, the location of the fat. !

• Android Obesity - obesity pattern seen in individuals who tend to store fat in the trunk or abdominal area. !

- Is seen in individuals who tend to store fat in the trunk or abdominal area (which produces the “apple” shape) !

• Gynoid Obesity - obesity pattern seen in people who store fat primarily around the hips & thighs. !

- Is seen in people who store fat primarily around the hips & thighs (which creates the “pear” shape). !

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• Obese individuals w/ abdominal fat are at higher risk for: ! - heart disease, ! - hypertension, ! - type 2%diabetes (“non–insulin-dependent” diabetes), ! - stroke, ! - some types of cancer, ! - kidney disease, ! - migraines, ! - & diminished lung function. ! • Abdominal fat has also been shown to triple the risk of dementia in older adults. ! • Human infants keep warm w/ the help of brown fat stored around their neck & shoulders. !

➡ Subcutaneous & Visceral Fat ! • Large abdominal girth is a risk factor all its own. ! • Subcutaneous Fat - deposits of fat directly under the skin. ! - Fat you can grasp just beneath the skin. ! - Sub- means “beneath” !

- -cutaneous comes from the original Latin word cutis meaning “skin” ! - People have a better metabolic profile than those w/ fat stored primarily as visceral fat. !

- Subcutaneous fat cells release ! ‣ more beneficial hormones,%! ‣ communicating w/ the brain to suppress appetite ! ‣ & burn stored fat ! ‣ & w/ the liver & muscles to increase sensitivity to insulin. ! - When a person gains fat weight, however, the hormone that increases sensitivity to insulin slows down OR stops entirely. ! 7

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• Visceral Fat - fat deposits located around internal organs linked w/ greater risk for disease; also called intra-abdominal fat. !

- Located around the liver, intestines, & other abdominal organs & in an apron of tissue that lies under the abdominal muscles. !

- Also known as intra-abdominal fat. ! - Visceral means “deep & inward” ! - Poses a much greater risk for disease than subcutaneous fat. ! - Creates proteins that: ! ‣ encourage low-level inflammation, ! ‣ proteins that encourage blood vessels to constrict, ! ‣ & proteins that increase insulin resistance. ! - Metabolizes into fatty acids more readily than subcutaneous fat. ! ‣ Making visceral fat respond more efficiently to diet & esp to exercise.! - Retroperitoneal Fat - fat deposits in the abdominal cavity behind (retro) the peritoneum. !

‣ Is located behind (retro) the abdominal cavity & is often measured as part of visceral fat. !

- A healthy diet alone will begin to reduce visceral fat stores, but exercise appears to be especially effective for burning away visceral fat from around your waistline. !

- A person who exercises regularly will reduce visceral fat & increase lean body mass even if weight is NOT lost. !

- The same positive lifestyle changes that improve other aspects of health have been directly tied to avoiding abdominal adiposity. !

‣ Individuals who: ! - DON’T smoke, ! - have healthy sleep patterns, ! - are less prone to hostility or depression, ! 8

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- & avoid fructose-sweetened foods & hydrogenated vegetable oils ! - Are less likely to have their adipose tissue stored as visceral fat. ! • Body fat in physically active individuals is less likely to be stored as visceral fat, whereas inactive individuals store a greater amount of visceral fat. !

Cengage CH.4 Book Notes | Section 4.4 “Techniques to Assess Body Composition” ➡ Techniques to Assess Body Composition ! • There is no method that can determine a person’s exact amount of body fat. ! - Some are just more accurate than others. ! • The SEE is a measure of the accuracy of the prediction for each specific technique, determining how many percentage points a result may deviate from the true percentage. !

- EX: If the SEE for a given technique is 3.0 & the individual tests at a fat % of 18.0, the actual fat % may range from 15 to 21%. !

• The dual energy x-ray absorptiometry (DXA) technique to assess body composition & bone density. !

➡ Dual Energy X-ray Absorptiometry ! • Dual Energy X-ray absorptiometry (DXA) - method to assess body composition that uses very low-dose beams of x-ray energy to measure total body fat mass, fat distribution pattern, & bone density. !

- Used most frequently in research & by medical facilities. ! - A radiographic technique ! - DXA uses very low-dose beams of x-ray energy (100’s of times lower than a typical body x-ray) to measure: !

‣ total body fat mass, ! ‣ fat distribution pattern, ! ‣ & bone density. ! 9

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- Bone density is measured to assess the risk for osteoporosis.%! - Procedure is simple & takes less than 15 mins to administer. ! - Many exercise scientists consider DXA to be the standard technique to assess body composition. !

- Due to costs, however, DXA is not readily available to most fitness participants. !

• Other methods to estimate body composition are used. The most common of these are: !

- (1) Hydrostatic OR Underwater weighing ! - (2) Air displacement ! - (3) Skinfold thickness ! - (4) Girth measurements ! - (5) Bioelectrical impedance ! • When assessing changes in body composition, be sure to use the same technique for pre- & post-test comparisons. !

- These procedures yield estimate of body fat, each technique may yield slightly different values. !

• Equipment is costly. ! • Not easily accessible to the general population. ! • Some of these methods also provide information on: ! - Total body water, ! - & bone mass. ! • These techniques include: ! - Air displacement, ! - magnetic resonance imaging (MRI), ! - computed tomography (CT), ! - & total body electrical conductivity (TOBEC). !

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➡ Hydrostatic Weighing ! • Hydrostatic Weighing - underwater techniques to assess body composition; considered the most accurate of the body composition assessment techniques. !

- Had been the most common technique used in determining body composition in exercise physiology laboratories. !

- W/ hydrostatic weighing, a person’s “regular” weight is compared w/ a weight taken underwater. !

‣ Since fat is more buoyant than lean tissue, comparing the 2 weights can determine a person’s % of fat. !

‣ Procedure requires: ! ‣ a considerable amount of time, ! ‣ skill, ! ‣ space, ! ‣ & equipment & must be administered by a well-trained technician. ! - This technique has several drawbacks. ! ‣ (1) Each individual assessment can take as long as 30 mins, hydrostatic weighing is NOT practical when testing a lot of people. !

‣ (2) The person’s residual lung volume should be measured before testing. !

- If residual volume cannot be measured, it’s estimated using the predicting equations, which may decrease the accuracy of hydrostatic weighing. !

‣ (3) Requirement of being completely underwater makes hydrostatic weighing difficult to administer to aquaphobic people. !

- Aquaphobic - having a fear of water. ! - Individual must force all of the air out of their lungs to obtain an accurate reading. !

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- Fat is less dense than water, overweight individuals weigh less in water. !

- Additional air in the lungs makes a person lighter in water, yielding a false, higher body fat percentage. !

• Hydrostatic - underwater weighing technique. • Bod Pod - used for assessment of body composition. ! ➡ Air Displacement ! • Air Displacement - technique to assess body composition by calculating the body volume from the air replaced by an individual sitting inside a small chamber. !

- AKA Air Displacement Plethysmography ! - An individual sits inside a Bod Pod ! - Bod Pod - commercial name of the equipment used to assess body composition through the air displacement technique. !

- Body volume calculated by subtracting the air volume w/ the person inside the chamber from the volume of the empty chamber. !

- Bone density & % body fat then are calculated from the obtained body volume. !

- Takes about 15 mins. ! - Compares favorably w/ hydrostatic weighing while being less cumbersome to administer. !

- Subsequent research determined that percent body fat is about 5 percentage points higher with air displacement than with hydrostatic weighing. !

• Various types of calipers used to assess skinfold thickness. ! • Chest & suprailium skinfold assessments. ! ➡ Skinfold Thickness ! • Most health & fitness programs use anthropometric measurement techniques. ! 12

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- Because of cost, time, & complexity of hydrostatic weighing! - Because of Bod Pod equipment ! - Primarily skinfold thickness & girth measurements, allow quick, simple, & inexpensive estimates of body composition. !

• Skinfold Thickness - technique to assess body composition by measuring a double thickness of skin at specific body sites. !

- Is based on the principle that the amount of subcutaneous fat is proportional to total body fat. !

- Valid & reliable measurements of this tissue give a good indication of percent body fat. !

- Is done w/ the aid of press calipers. ! - All measurements should be taken on the right side of the body. ! ‣ Women: triceps, suprailium, & thigh skinfolds ! ‣ Men: chest, abdomen, & thigh ! - Training is necessary to obtain accurate measurements. ! - The same technique should take pre- & post-test measurements. ! - Measurements should be done at the same time of the day—preferably in the morning—because changes in water hydration from activity & exercise can affect skinfold girth. !

➡ Girth Measurements ! • Girth Measurements - technique to assess body composition by measuring circumferences at specific body sites. !

- Method that’s frequently used to estimate body fat is to measure circumferences, or at various body sites. !

- Requires only a standard measuring tape. ! - The limitation may not be valid for athletic individuals (men OR women) who participate actively in strenuous physical activity OR for people who can be classified visually as thin OR obese. !

➡ Bioelectrical Impedance ! 13

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• Bioelectrical Impedance - technique to assess body composition by running a weak electrical current through the body. !

- Much simpler technique to administer ! - Its accuracy is questionable though ! - Sensors are applied to the skin & a weak (painless) electrical current is run through the body to measure its electrical resistance. !

‣ Which is then used to estimate ! - body fat, ! - lean body mass, ! - & body water. ! - Based on the principle that fat tissue is a less efficient conductor of electrical current than is lean tissue. !

- The easier the conductance is, the leaner the individual. ! - The accuracy of equations used to estimate percent body fat with this technique may not be reliable. !

- A single equation can’t be used for everyone, but rather valid & accurate equations to estimate body fat for the specific population (age, gender, & ethnicity) are required. !

- Several factors can affect the results, including the individual’s: ! ‣ water intake ! ‣ & body temperature. !

Cengage CH.4 Book Notes | Section 4.5 “Metrics Used to Assess Body Size & Shape” ➡ Body Mass Index ! • Body Mass Index (BMI) - technique to determine thinner & excessive fatness that incorporates height...