Transcript Body Composition

Chapter 4
Health-Related Physical Fitness
Testing and Interpretation
WORDING IN RED WILL
DEFINITELY BE ON THE TEST
Copyright © 2010 American College of Sports Medicine
Announcements
• Labs next week (March 1, 3-4) will be in 213 MAC.
• Remember next week is the ECG test during lab
times.
• No labs March 8, 10-11.
• Labs March 22, 24-25, and 28, 30-31 will be in 150
MAC
• Labs starting April 5th will be back in 213 MAC.
The health-related components of physical fitness:
• have a strong relationship with good health,
• are characterized by an ability to perform daily
activities with vigor, and
• demonstrate the traits and capacities associated
with low risk of premature development of the
hypokinetic diseases (e.g., those associated with
physical inactivity)
Purposes of Health-Related Fitness
Testing
• Educating participants about their present health-related
fitness status relative to health-related standards and age- and
sex-matched norms
• Providing data that are helpful in the development of exercise
prescriptions to address all fitness components
• Collecting baseline and follow-up data that allow evaluation of
progress by exercise program participants
• Motivating participants by establishing reasonable and
attainable fitness goals
• Stratifying cardiovascular risk
Basic Principles and Guidelines
• An ideal health-related physical fitness test:
– is reliable, valid, relatively inexpensive, and easy to
administer, and
– should yield results that are indicative of the current
state of fitness, reflect change from physical activity or
exercise intervention, and be directly comparable to
normative data.
Pretest Instructions
• A minimal recommendation is that individuals
complete a questionnaire such as the Physical
Activity Readiness Questionnaire (PAR-Q) or
the ACSM/AHA form.
• A listing of preliminary instructions for all
clients can be found in Chapter 3 (Patient
Instructions). These instructions may be
modified to meet specific needs and
circumstances.
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Test Order
• The following should be accomplished before
the participant arrives at the test site:
– Ensure that all forms, score sheets, tables, graphs,
and other testing documents are organized and
available for the test’s administration.
– Calibrate all equipment a minimum of once each
month to ensure accuracy (e.g., metronome, cycle
ergometer, treadmill, sphygmomanometer,
skinfold calipers).
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Test Order
– Organize equipment so that tests can follow in sequence
without stressing the same muscle group repeatedly.
– Provide informed consent form.
– Maintain room temperature of 68°F to 72°F (20°C to
22°C) and humidity of <60%.
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Test Order (cont.)
• Testing CR endurance after assessing muscular fitness
(which elevates HR) can produce inaccurate results
about an individual’s CR endurance status, particularly
when tests using HR to predict aerobic fitness are used.
• Dehydration resulting from CR endurance tests might
influence body composition values if measured by
bioelectrical impedance analysis (BIA).
• Because certain medications, such as beta-blockers,
which lower HR, will affect some fitness test results,
use of these medications should be noted.
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Test Environment
• Test anxiety, emotional problems, food in the
stomach, bladder distention, room temperature,
and ventilation should be controlled as much as
possible.
• To minimize anxiety, the test procedures should
be explained adequately, and the test
environment should be quiet and private.
• The room should be equipped with a comfortable
seat and/or examination table to be used for
resting BP and HR and/or ECG recordings.
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Test Environment (cont.)
• The demeanor of personnel should be one of
relaxed confidence to put the subject at ease.
• Testing procedures should not be rushed, and
all procedures must be explained clearly prior
to initiating the process.
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Test Order
• Resting measurements • When all fitness components are
should be obtained first assessed in a single session, resting
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Heart rate
Blood pressure
Height
Weight
Body composition
measurements should be followed (in
order) by tests of:
- cardiorespiratory (CR) endurance,
- muscular fitness, and
- flexibility.
Copyright © 2010 American College of Sports Medicine
Body Composition
• Before collecting data for body composition
assessment, the technician must be trained,
routinely practiced in the techniques, and already
have demonstrated reliability in his or her
measurements, independent of the technique being
used.
• Experience can be accrued under the direct
supervision of a highly qualified mentor in a
controlled testing environment.
•
•
Body Composition
67% and 32% of American adults
are classified as overweight and
obese.
Anthropometric methods
– Body mass index
– Circumferences
– Skinfold measurements
Densitometry
– Hydrodensitometry (underwater)
weighing
– Plethysmography
•
Other techniques
– Dual energy x-ray absorptiometry
– Total body electrical conductivity
– Bioelectrical impedance analysis
– Near-infrared intercadence
Body Mass Index (BMI)
• The BMI is used to assess weight relative to height
and is calculated by dividing body weight in
kilograms by height in meters squared (kg·m-2)
• For most people, obesity-related health problems
increase beyond a BMI of 25, and the Expert Panel
on the Identification, Evaluation, and Treatment of
Overweight and Obesity in Adults lists a BMI of 25.0
to 29.9 kg·m-2 for overweight and a BMI of ≥30.0
kg·m-2 for obesity.
Know: Body Type or Somatype
Pg. 63
Know BMI categories below
Pg. 64
Android
Vs.
Gynoid
The ratio of waist-to-hip
circumference (WHR) has been
used to determine android vs.
gynoid type of obesity. The waist
circumference is the smallest
circumference below the rib cage
and above the umbilicus. The hip
circumference is the largest
circumference of the buttocks-hip
area. The waist circumference
alone is also used than the WHR.
Circumferences
• The pattern of body fat distribution is recognized as an
important predictor of the health risks of obesity.
• Android obesity, which is characterized by more fat on
the trunk (abdominal fat), provides an increased risk
of hypertension, metabolic syndrome, type 2 diabetes,
dyslipidemia, coronary artery disease, and premature
death compared with individuals who demonstrate
gynoid or gynecoid obesity (fat distributed in the hip
and thigh).
• Significant amounts of waist circumference are:
40 inches for males and 35 inches for females. Above
these values disease risk increases.
Circumferences (cont.)
• Procedures
– All measurements should be made with a flexible yet
inelastic tape measure.
– The tape should be placed on the skin surface without
compressing the subcutaneous adipose tissue.
– If a Gulick spring-loaded handle is used, the handle
should be extended to the same marking with each trial.
Circumferences (cont.)
• Procedures (cont.)
– Take duplicate measures at each site and retest if
duplicate measurements are not within 5 mm.
– Rotate through measurement sites or allow time for
skin to regain normal texture.
• Waist-to-hip ratio (WHR)
– The waist-to-hip ratio is the circumference of the waist
divided by the circumference of the hips (buttocks/hips
measure) and has been used as a simple method for
determining body fat distribution.
– Health risk increases with WHR, and standards for risk
vary with age and sex.
• Waist-to-hip ratio (cont.)
– Health risk is very high for young men when WHR is
>0.95 and for young women when WHR is >0.86.
– For people 60 to 69 years old, the WHR values are >1.03
for men and >0.90 for women for the same risk
classification.
Skinfold Measurements
When performed correctly, skinfold
measures provide an fairly good
estimate of percent body fat (r = 0.700.90 with underwater weighing). The
goal is to measure a double fold of skin
and subcutaneous tissue (with sides of
skinfold approximately parallel). The
thicker the fat layer, the wider the fold.
Technician error is the greatest source
of error.
• Skinfolds measure subcutaneous fat.
• Amount of subcutaneous fat is proportional to
the total amount of body fat.
• It is assumed that close to one-third of the
total fat is located subcutaneously.
• The exact proportion of subcutaneous to total
fat varies with sex, age, and ethnicity.
• Regression equations used to convert sum of
skinfolds to percent body fat must consider
these variables for greatest accuracy.
• Skinfold Procedures – page 67, Box 4.2
– All measurements should be made on the right side
of the body with the subject standing upright.
– Caliper should be placed directly on the skin surface,
1 cm away from the thumb and finger, perpendicular
to the skinfold, and halfway between the crest and
the base of the fold.
– Pinch should be maintained while reading the caliper.
• Skinfold Procedures (cont.)
– Wait 1 to 2 seconds (not longer) before reading
caliper.
– Take duplicate measures at each site and retest if
duplicate measurements are not within 1 to 2 mm.
– Rotate through measurement sites or allow time for
skin to regain normal texture and thickness (at least
15 seconds apart).
• Do not take measurements when the subject's skin
is moist (ensure that the skin is dry, and has no
lotion). Also do not take measurements
immediately after exercise or when the person
being measured is overheated because the shift of
body fluid to the skin will inflate normal skinfold
size.
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• Factors that may contribute to measurement
error within skinfold assessment include:
– poor technique,
– an inexperienced evaluator,
– an extremely obese or extremely lean subject, and
– an improperly calibrated caliper (tension should
be set at ~12 g·mm-2).
Abdomen Skinfold
Vertical fold 2 cm to
the right of the
umbilicus.
Horizontal fold, one inch to the right
side of and ½ inch below the navel.
Alternate method
-will not be done in 4315
Triceps Skinfold
Vertical fold on posterior midline
of the upper arm, halfway
between the acromion and
olecranon process, with the arm
held freely to the side of the
body.
Chest Skinfold
the chest/pectoral skinfold
site is one half the distance
between the anterior axillary
line and the nipple for men,
and one third of this distance
for women
Midaxillary Skinfold
Vertical fold taken on
midaxillary line at level of
xiphisternal junction.
Subscapular Skinfold
Diagonal fold just below the
inferior angle of scapula.
Suprailiac Skinfold
a diagonal fold is taken
with the natural angle
of the iliac crest at the
anterior axillary line
immediately superior
to the iliac crest
Alternate method: Diagonal fold
just above iliac crest at the
midaxillary line.
Thigh Skinfold
Vertical fold on anterior
thigh, midway between
inguinal crease and
proximal border of patella.
Densitometry
• Whole-body density, using the ratio of body mass to
body volume
– In this technique, the body is divided into two
components: the fat mass (FM) and the fat-free mass
(FFM). TWO COMPARTMENT MODEL.
– The limiting factor in the measurement of body density
is the accuracy of the body volume measurement
because body mass is measured simply as body weight.
– RESIDUAL VOLUME is the issue
• Hydrodensitometry (underwater) weighing
– Based on Archimedes’ principle
• When a body is immersed in water, it is buoyed by a
counterforce equal to the weight of the water displaced.
• Bone and muscle tissue are denser than water, whereas fat
tissue is less dense. Therefore, a person with more FFM for
the same total body mass weighs more in water and has a
higher body density and lower percentage of body fat.
• Subjects must follow pre-test guidelines
completely. (no food ingestion 4 hrs prior,
smoking, caffeine, exercise).
• 5-10 trials necessary
• light weight clothing needed, removal of air
bubbles from suit, hair, and skin while
underwater.
Copyright © 2010 American College of Sports Medicine
Body Density (Db) = body mass (g) / body volume
(mL)
Db = Wa / {[(Wa - Ww) / Dw] - (RV + 100 mL)}
where;
Db = body density (g/mL)
Wa = body mass out of water
Ww = body mass underwater
Dw = density of water (g/mL)
RV = residual lung volume (mL)
100 mL = volume of air trapped in
gastrointestinal tract that cannot be
measured.
Siri Equation - % body fat = [(4.95 / Db) - 4.50] x 100
Brozek Equation - % body fat = [(4.57 / Db) - 4.142] x
100
Plethysmography
• Measured by air rather than water displacement
• Based on 2 compartment model as well.
• Uses a dual-chamber plethysmograph that
measures body volume by changes in pressure in
a closed chamber
• This technology shows promise and generally
reduces the anxiety associated with the
technique of hydrodensitometry.
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Other Techniques
• Dual energy x-ray absorptiometry (DEXA) and total body
electrical conductivity (TOBEC) are reliable and accurate
measures of body composition, but these techniques are
not popular for general health fitness testing because of
cost and the need for highly trained personnel.
• BIA and near-infrared intercadence are used for general
health fitness testing. The accuracy of BIA is similar to
skinfolds, as long as a stringent protocol is followed and the
equations are valid and accurate for the populations being
tested. Near-infrared intercadence requires additional
research to substantiate the validity and accuracy for body
composition assessment.
Copyright © 2010 American College of Sports Medicine
Bioelectrical Impedance
• Bioelectrical impedance (BIA)
 Based on the premise that the volume of fat fee tissue will
be proportional to the electrical conductivity of the body
• Passes a small electrical current into the body and measures
resistance
–Fat is a poor conductor of electricity
–Lean body tissue (mostly water) will be a
good electrical conductor
• BIA is acceptable when measuring total body water
• BIA is not as accurate for % of body Fat (Hydration levels)
Techniques
• BIOELECTRICAL IMPEDANCE (BIA)
 Relatively new technique
 Dependent upon several assumptions (State of hydration)
 Standard Error about the same as skinfold technique
• More costly
• Quicker than skinfolds
• Privacy less of a problem
 Looks more high tech than other methods
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BIA Problems
• Electrolyte status may be altered due to:
• alcohol consumption (48 hrs)
• food or eating consumption (4 hrs)
• recent exercise (12 hrs)
• Urination 30 minutes of the test
BIA Problems
• Electrolyte status may be altered due to:
• diuretic therapy (Physician approved) within
7 days of the test
• menstrual cycle (avoid 3 days prior through
three days following or belief of water
retention. )
• Oil and lotions should be removed from the
skin
• Room should have normal ambient temperature.
Body Composition Norms
Table 4-5
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Body Composition Norms (cont.)
Table 4-6
Copyright © 2010 American College of Sports Medicine
• A consensus opinion for an exact percentage
body fat value associated with optimal health
risk has yet to be defined.
– A range of 10% to 22% and 20% to 32% for men
and women, respectively, is considered
satisfactory for health.
Copyright © 2010 American College of Sports Medicine