KIN 462 Notes 5b Body Composition

(1) ID individuals with low/high %BF (but no universally agree values) (2) Inform exercise prescription (set weight loss target/goal) (3) Assess weight loss/maintenance progress

% body fat methods can (3) - *There are no universally accepted norms for body composition*, however, + a range of 10-22% (men) and 20-32% (women) has been viewed as satisfactory for health include: (1) Skinfold measurements (2) Hydrodensitometry (underwater) weighing (3) Air Plethysmography (Bod Pod) (4) Bioelectrical Impdeance analysis (BIA) (5) Dual energy X-ray absorptiometry (DEXA)

Waist to Hip Ratio

*Waist Circumference divided by Hip circumference* - indicator of abdominal/visceral fat - Good predictor of obesity related health risk: + >0.95 (male); >0.86 (female) - especially in people aged 60-69 + >1.03 (males); >0.90 (females)

Body Composition

- can be expressed as the relative % of body mass that is fat and fat-free tissue using a two-compartment model - Before collecting data, technician must be trained and already have demonstrated reliability in measurement independent of the technique being used - 88.5% of adults rank weight/fat loss as a goal (Different Methods) (A) Anthropometric Methods (1) BMI (height and weight) (2) Waist Circumference (B) % Body Fat Methods (1) Skinfold measurements (2) Hydrodensitometry (underwater weighing) (3) Air Plethysmography (Bod Pod) (4) Bioelectrical Impdeance analysis (BIA) (5) Dual energy X-ray absorptiometry (DEXA) - Well established that excess body fat, particularly abdominal fat, is associated with hypertension, metabolic syndrome, type 2 diabetes mellitus, stroke, CVD and dyslipidemia + 2/3 of americans are overweight, 1/3 of americans are obese

Waist Circumference

1/2 Anthropometric Methods of assessing Body Composition - Abdominal (visceral) fat, is a more important determinant of health outcomes than overall body fatness _____ _____________: *> 102cm (males) > 88cm (females)* = predictor of obesity-related health risks (Type 2 Diabetes, hypertension, CAD, hyperlipidemia, metabolic syndrome, etc) - *especially useful to use in individuals with a BMI of 25-34.9kg/m2* _____ _____________ procedure - Measure at narrowest part of the torso (some recommended to take directly above iliac crest for standardization but no formulae exists) - Average of 2 measure provided the measures do not differ by >5mm (2) _____________ of other body parts can also be done Hips/Thign (taken at the maximal circumference of the hip/proximal thigh just below the gluteal fold), mid-thigh, abdomen, arm, buttocks/hips, calf and forearm (Sources of Error) (1) Positioning (narrowest vs superior border of iliac crest) (2) Tape level (3) Tissue compression (use spring loaded tape to help standardize degree of tension) (4) Measure after normal exhalation (5) Duplicate measures and average (Triplicate if not within 5mm) (6) Not measuring sites in rotational order (advantages) - same 5 as BMI (disadvantages) - Limited as an estimate of total body fatness (+/-4%)

Body Mass Index (BMI)

1/2 Anthropometric Methods of assessing Body Composition = kg/m2 - used to classify obese, overweight & underweight + limited as an index of body fat (+/- 5%) - Inaccurate for some groups (Athletes with extreme muscle mass, very short stature, resistance training [addition of muscle mass]) (advantages) - Cheap - Easy to use - Good at predicting Risk of Cardiovascular & metabolic disease (more important that %BF) - Good measure for majority of population - Great at tracking change in body composition - Combined with Waist Circumference it is more strongly related to CVD than ____ ____ _____ (___) alone *(1) Underweight = <18.5 (2) Normal = 18.5-24.9 (3) Overweight = 25.0-29.9 (4) Obese = >/= 30.0

Standing height

1/2 measures needed to calculate BMI (client) - No footwear - Stand erect with feet together - Heels and back against wall - Looking straight ahead - deep breath (measurement) - place set square on head - record ________ ______ to the nearest *0.5cm*

Body Mass (weight)

1/2 measures needed to calculate BMI (client) - without footwear and in light clothing (measurement) - ensure scale is on flat surface - board under scale if on carpet - record ____ ____ (______) to nearest *0.1kg* - Calibration of scale is important

Bioelectrical Impedence Analysis (BIA)

1/5 % body fat measurements - low level electrical current is passed through the body - Resistance/impedence to current is measured - Resistance influenced by: + Total body water (Fat has low H2O content) + Electrolytes good conductors (lean tissue composed of H2O and electrolytes) - Population specific equations to predict % body fat have been developed through research - Predicts FFM form resistance (equations available) - *Accuracy = +/- 2.7-6.3%* (*Pretest Instructions*) (1) No eating/drinking within 4hrs of test (2) No moderate-vigorous intensity exercise within 12 hours (3) Empty bladder within 30mins (4) No alcohol within 48hrs (5) No caffeine (standard protocol = \/3hrs) (6) Diuretics (influence water retention) (7) Menstrual cycle (influence water retention) (Limitations) - Assumes that current follows path of least resistance in body - Assumes body and it's segments conform to a 'typical' cylinder - Body hydration affects results - Provides no information on regional adiposity (Advantages) + noninvasive + quick to perform (Disadvantages) + strict pretest conditions + special equipment required (no additional health info beyond BMI & WC)

Air Plethysmography (Bod Pod)

1/5 % body fat measurements - measure body volume by aid displacement - large body volume displaces air volume in chamber + advantages vs Hydrodensitometry, but $$$ (advantages) - accuracy of measure (disadvantages) - cost - equipment - technical expertise

Hydrodensitometry

1/5 % body fat measurements - underwater weighing - Determines body density and % body fat by weighing the client both on land and while submerged in water. - Using Archimedes' principle and a series of equations, body density is determined, and then fat mass and fat free mass is calculated - When an individual is submerged in water, *body volume = loss of weight in water* (corrected for the density of water corresponding to the temperature of the water) - Body volume = (weight in air-weight in water)/Density of water - Density of water = 0.9937g/dl - needs to account for: + air in the lungs: residual volume measured using spirometry, individual expires before immersion + any mass in the gastrointestinal tract at the time of measurement (estimated at 100ml) (Equipment) - A large enough tank filled with water at a controlled temperature (32 to 35 Degrees) - A seat held by a transducer that can measure body weight underwater without the individual touching anything - Spirometry equipment for assessment of residual volume (Methods) (1) Weight the individual on a calibrated scale (2) Have the subject get into chair in tank (3) Give them a few trials to get accustomed to being lowered in water and remaining still after a maximal expiration (4) Assess residual volume with a spirometer (5) Have subject complete a maximal expiration (6) Measure weight in water (7) Complete three trials (Steps 4 to 6) and average body density values (sources of error/limitations) (1) Biological variability in fat free mass and its density (2) Human error (3) Inaccurate residual volume (4) Air left in lungs after forced expiration (5) Inaccurate GI estimation (6) air trapped in bathing suit/hair - *combined = +/- 2% (Assumptions) (1) assuming the density of fat mass is constant (D[fat] = 0.90g/ml) (2) The density of various FFM components are constant (D[FFM] = 1.10g/ml; impact of osteoporosis) (3) These densities are the same in all individuals Obesity = >22% (males); > 35% (females) (advantages) - accurate (disadvantages) (1) cost (2) equipment (3) technical expertise (4) Time consuming (no additional health benefits beyond BMI & WC)

Dual energy x-ray absorptiometry (DEXA)

1/5 % body fat measurements - xray that determines + lean soft tissue mass + fat free mass + fat mass + bone mineral content - very sensitive to body composition changes (limitation with other methods) (advantages) - High validity and reliabilty (*+/- 1.8%*) - allows for estimation of both total and regional body composition (disadvantages) - high cost - limited availability - equipment - technical expertise

Skinfold measurements

1/5 % body fat measurements ________ ____________ - "doubly indirect" - measure thickness of (1)_______s at various sites + can be used to predict %body fat with population specific prediction equations using individual (1)________ measures or sum of (1)________ + *accuracy = +/- 3.5% (at best)* *3 Assumptions* (1) *Subcutaneous fat proportional to total body fat* (assumably roughly 1/3 body fat: varies with age, gender, ethnicity etc though) (2) *Skinfold measures (sites) are representative of subcutaneous fat* (# of sites) (3) *Thickness/Compressibility of skin is negligible/constant* (Advantages) (1) Cheap (Disadvantages/Limitations) (1) Invasive (2) Source of error (intra & inter observer variability) (3) Time consuming (training, practice, accurate administration) (4) No information on health risk (beyond BMI & WC) (Sources of error) (1) Landmarking/Locating site (2) Skill/Technique (3) Inter-tester reliability (experience) (4) Caliper (tension, calibrated) (5) Use appropriate equation (gender, ethnicity, age, etc) (6) Extremely Obese/Lean client (7) Hydration Status (not after exercise) (Procedure) - Take all measurements on the right side of the body - Identify and mark site - Firmly grasp (pinch) 1 cm above (1)________ - Place calipers on (1)________ - Record reading 1 to 2 seconds after releasing grip of calipers. Maintain pinch grip. - Take duplicate measures at each site and retest if duplicate measurements are not within 1-2 mm - Sum the average of each site - Rotate through all sites before repeating (sites) - Abdominal, Triceps, Biceps, Pectoralis, Chest, Mid Axillary, Subscapular, Calf, Suprailiac, Thigh

(1) *Subcutaneous fat proportional to total body fat* (assumably roughly 1/3 body fat: varies with age, gender, ethnicity etc though) (2) *Skinfold measures (sites) are representative of subcutaneous fat* (# of sites) (3) *Thickness/Compressibility of skin is negligible/constant*

3 Assumptions with Skinfold measurements

(advantages) (1) accuracy of measure (disadvantages) (1) cost (2) equipment (3) technical expertise (no additional health benefits beyond BMI & WC)

Advantages (1) and disadvantages (3) of Air Plethysmography (Bod Pod)

(advantages) (1) accuracy of measure (disadvantages) (1) cost (2) equipment (3) technical expertise (4) Time consuming (no additional health benefits beyond BMI & WC)

Advantages (1) and disadvantages (4) of Hydrodensitometry

(Advantages) (1) noninvasive (2) quick to perform (Disadvantages) (1) strict pretest conditions (2) special equipment required (no additional health info beyond BMI & WC)

Advantages (2) and Disadvantages (2) of *bioelectrical impedance analyzer (BIA)*

(Advantages) (1) Cheap (Disadvantages) (1) Invasive (2) Source of error (intra & inter observer variability) (3) Time consuming (training, practice, accurate administration) (4) No information on health risk (beyond BMI & WC)

Advantages (2) and Disadvantages (4) of skinfold measurements Not recommended due to above disadvantages/limitations

(advantages) (1) High validity and reliabilty (*+/- 1.8%*) (2) allows for estimation of both total and regional body composition (disadvantages) (1) high cost (2) limited availability (3) equipment (4) technical expertise

Advantages (2) and disadvantages (4) of Dual energy x-ray absorptiometry (DEXA)

(1) Inexpensive (2) Easy to use (3) Good at predicting Risk of Cardiovascular & metabolic disease (more important that %BF) (when BMI & WC are combined, more strongly related to CVD than alone) (4) Good measure for majority of population (extreme muscle mass, very short, people undergoing resistance training) (5) Great at tracking change in body composition

Advantages of BMI & Waist Circumference (5)

(1) assuming the density of fat mass is constant (D[fat] = 0.90g/ml) (2) The density of various FFM components are constant (D[FFM] = 1.10g/ml; impact of osteoporosis) (3) These densities are the same in all individuals

Assumptions with Hydrodensitometry (3)

(1) 18.5 (2) 18.5-24.9 (3) 25.0-29.9 (4) 30.0 (5) 102 (6) 88

BMI (1) Underweight = <__._% (2) Normal = __._-__._% (3) Overweight = __._-__._% (4) Obese = >/= __._% Waist Circumference Obese = (5) >___cm (male) (6) >__cm (female)

Athletes with extreme muscle mass Short stature Resistance training (addition of muscle mass)

BMI may not be a suitable method for tracking weight-related health risk in (3)

%BF

How much weight to lose? - Using ___ + Goal = 19% BF, 81%FFM e.g. Current: Body Weight = 91 kg, %BF = 22% - FFM = 70.1 kg, FM = 19.9 kg - Goal = 19% BF, 81%FFM + Assume FFM remains constant - So, what body weight will 70.1 kg be 81%? (1) 70.1 kg ÷ .81 (2) = 86.5 kg (3) 91 kg - 86.5 kg (4) = 5.5 kg = Weight loss goal (5) 5.5 kg x 2.2 = 12.1 lb

year

In healthy individuals, BMI and WC should be measured every ____, if not more frequently - to track changes in weight and fat distribution and identify adults who may be at an elevated risk of mortality from all causes

(1) Assumes that current follows path of least resistance in body (2) Assumes body and it's segments conform to a 'typical' cylinder (3) Body hydration affects results (4) Provides no information on regional adiposity

Limitations of *bioelectrical impedance analyzer (BIA)* (4) Not recommended due to above limitations

(1) No eating/drinking within 4hrs of test (2) No moderate-vigorous intensity exercise within 12 hours (3) Empty bladder within 30mins (4) No alcohol within 48hrs (5) No caffeine (standard protocol = \/3hrs) (6) Diuretics (influence water retention) (7) Menstrual cycle (influence water retention)

Pretest Instructions that clients need to follow for their *bioelectrical impedance analyzer (BIA)* measures to be accurate (7)

(1) Biological variability in fat free mass and its density (2) Human error (3) Inaccurate residual volume (4) Air left in lungs after forced expiration (5) Inaccurate GI estimation (6) air trapped in bathing suit/hair

Sources of error (limitations) with Hydrodensitometry (6) - *all combined = +/- 2%

(1) Landmarking/Locating site (2) Skill/Technique (3) Inter-tester reliability (experience) (4) Caliper (tension, calibrated) (5) Use appropriate equation (gender, ethnicity, age, etc) (6) Extremely Obese/Lean client (7) Hydration Status (not after exercise)

Sources of error that need to be controlled for in skinfold measurement technique

(1) Positioning (narrowest vs superior border of iliac crest) (2) Tape level (3) Tissue compression (use spring loaded tape to help standardize degree of tension) (4) Measure after normal exhalation (5) Duplicate measures and average (Triplicate if not within 5mm) (6) Not measuring sites in rotational order

Sources of error with Waist Circumference measurement (6)

% body fat

_ ____ ___ methods - these methods can (1) ID individuals with low/high %BF (but no universally agree values) (2) Inform exercise prescription (set weight loss target/goal) (3) Assess weight loss/maintenance progress - *There are no universally accepted norms for body composition*, however, + a range of 10-22% (men) and 20-32% (women) has been viewed as satisfactory for health include: (1) Skinfold measurements (2) Hydrodensitometry (underwater) weighing (3) Air Plethysmography (Bod Pod) (4) Bioelectrical Impdeance analysis (BIA) (5) Dual energy X-ray absorptiometry (DEXA)

Physical activity

________ ________ preferentially reduces visceral adipose tissue (VAT) even if body weight does not change + Indications of change in visceral adipose (i.e waist circumference) would therefore be the most likely to show a positive change in body composition (remember you want your tests to pick up on positive changes + reduction in VAT has been shown independent of weight loss ________ ________ is a better measure of Risk of disease than overweight/obesity

Densitometry

____________ = estimating body composition from density (body weight/body volume) - need to determine body volume - most common techniques (1) Hydro____________ (2) Air Plethysmography (Bod Pod)