Docstoc

Box Standardized Description of Skinfold Sites and Procedures

Document Sample
Box Standardized Description of Skinfold Sites and Procedures Powered By Docstoc
					  Body
Composition
Body Composition
2 component model

     Fat tissue
   Fat free tissue
        Body Composition
                 Why the interest?
Excess body fat
• Hypertension
• Type 2 diabetes
• Hyperlipidemia
• Certain cancers
• Poor performance/function
• Poor self-image
Incident of overweight is ↑ng
Want to “look good”
       Body Composition
            Terminology
Depot or storage fat – fat stored in
 adipose cells as nutritional reserve

Essential fats – fats necessary for
 normal physiologic function
      Body Composition
           Terminology
Lean body mass (wt) – body mass
 minus depot fat

Fat free mass (wt) – body mass minus
 all fat (depot & essential)
     Body Composition
Relative %age of body weight that is
 fat & fat-free tissue

Lab & field tests vary in complexity,
 expense
Anthropometry
Measurement of
the human body
Anthropometry
           Ht/wt
   Circumference/girths
         Skinfolds
   Hydrostatic weighing
  Bioelectrical impedance
            DXA
          TOBEC
           X-ray
 Body Composition - %Fat
         Norms
 Classification       Women          Men
Essential Fat     11.0 - 14.0   3.0 - 5.0
Athletes          12.0 – 22.0   5.0 – 13.0
Fitness           16.0 - 25.0   12.0 – 18.0
Potential Risk    26.0 – 31.0   19.0 – 24.0
Obese               ≥ 32.0         ≥ 25.0
Body Composition - Tests
• Densitometry
 – Two component model
   • Fat & fat free mass
 – Ratio of body mass to body volume
   (DB=BW/BV)
 – Body mass determined form body weight
 – Body volume from under water weighing or
   plethysmography
     Densitometry
• Hydrostatic (under water)
  weighing
 –Criterion, gold standard
        Densitometry
• Hydrostatic (under water) weighing
  – Archimedes’ principle – when a body is
    immersed in water, it is buoyed by a
    counterforce equal to the weight of the water
    displaced

  – The loss of weight in water, corrected for
    density of the water, allows calculation of
    body volume
        Densitometry
•   RV
•   Density of H2O
•   Trapped gas in GI tract (100 ml)
•   Body weight (dry)
•   Body weight (wet)
      Body Composition -
        Densitometry
Body density =

                 weight in air
(weight in air – weight in water) – Residual
     Density of the water             volume
    Body Composition -
      Densitometry

Body density = bone & muscle
 more dense than water, fat
 tissue less dense
    Body Composition -
      Densitometry

Plethysmography
• air displacement – Δs in pressure
  in a closed chamber
Bodpod
   Body Composition -
     Densitometry
%fat =       457        - 414.2
         Body Density

%fat =       495        - 450
         Body Density
  Body Composition –
Anthropometric Methods
     •   Height
     •   Weight
     •   Circumferences
     •   Skinfolds
       Body Composition –
     Anthropometric Methods
• Reliability & validity
  – Skill of the measurer
  – Type of caliper or tape measure
  – Subject factors related to skinfold
    compressibility, edema, & variability in
    fat pattern & distribution
  – Prediction equation used to estimate
    fatness
        Body Composition –
      Anthropometric Methods
• Body Mass Index (BMI)
  –   Assess weight relative to height
  –   [body weight (kg)/height (m2)]
  –   BMI > 25 – increased health risk
  –   25.0 to 29.9 = Overweight
  –   > 30 = Obese
  –   See Table 4-1 pg.58 & Table 4-2 pg.59
           Body Composition –
         Anthropometric Methods
• Waist-to-hip circumference
  – Body fat distribution
  – More fat on trunk (abdominal fat) = greater risk
    of HTN, type 2 diabetes, hyperlipidemia, CAD,
    premature death
  – Health risk is high
     •   W/H ratio > 0.94 in young men
     •   W/H ratio > 0.82 in young women
     •   W/H ratio > 1.03 in men 60-69 yrs
     •   W/H ratio > 0.90 in women 60-69 yrs

                             See Box 4-1 & Table 4-3 pgs.60-61 ACSM GET&P
Classification of Disease Risk Based
on Body mass Index (BMI) and Waist
     Circumference (Table4-1)
              Disease Risk Relative to normal
              Weight and Waist Circumference
      Body Composition –
    Anthropometric Methods


• Skinfolds
  – Amount of subcutaneous fat is
    proportional to total body fat
    Box 4-2. Standardized Description of
   Skinfold Sites & Procedures Continued

• Procedures
  – All measurements on the right side of the body
  – Caliper should be placed 1 cm away from the thumb
    & finger, perpendicular to the skinfold, & halfway
    b/n the crest & the base of the fold
 Box 4-2. Standardized Description of
   Skinfold Sites and Procedures
              Continued
– Pinch should be maintained while reading the
  caliper
– Wait 1 to 2 s (& not longer) before reading
  caliper
– Take duplicate measures at each site & retest if
  duplicate measurements are not w/n 1 to 2 mm
– Rotate through measurement sites or allow
  time for skin to regain normal texture &
  thickness
     Box 4-2. Standardized Description of
        Skinfold Sites & Procedures

• Skinfold Site
  – Abdominal     Vertical fold; 2cm to the right side of
                  the umbilicus
  – Triceps       Vertical fold; on the posterior
                  midline of the upper arm, halfway
                  between the acromion & the
                  olecranon processes, w/ the arm held
                  freely to the side of the body
  – Biceps        Vertical fold; on the anterior aspect of the
                  arm over the belly of the biceps muscle, 1
                  cm above the level used to mark the
                  triceps site
   Box 4-2. Standardized Description of
  Skinfold Sites & Procedures Continued
• Skinfold Site Continued
  – Chest/Pectoral    Diagonal fold; one-half the
                      distance between the anterior axillary
                      line & the nipple (men) or one-third
                      the distance b/n the anterior
                      axillary line & the nipple (women)

  – Medial Calf       Vertical fold; at the maximum
                      circumference of the calf on the
                      midline of its medial border
     Box 4-2. Standardized Description of
    Skinfold Sites & Procedures Continued

• Skinfold Site Continued
  – Midaxillary      Vertical fold; on the midaxillary line at
                     the level of the xiphoid process of the
                     sternum (An alternate method is a
                     horizontal fold taken at the level of the
                     xiphoid/sternal in the midaxillary line


  – Subscapular      Diagonal fold (at a 45 angle); 1 to 2
                     cm below the inferior angle of the
                     scapula
  Box 4-2. Standardized Description of
 Skinfold Sites & Procedures Continued
• Suprailiac   Diagonal fold; in line w/
               the natural angle of the iliac
               crest taken in the anterior
               axillary line immediately
               superior to the iliac crest

• Thigh        Vertical fold; on the anterior
               midline of the thigh, midway
               b/ the proximal border
               of the patella & the
               inguinal crease (hip)
Table 4-5. Body Composition (%Body Fat)
                For Men*
Table 4-6. Body Composition (%Body Fat)
              For Women*
    Body Composition – Other
          Techniques
• Bioelectrical Impedance Analysis (BIA)
  – Volume of FFM is proportional to the electrical
    conductivity of the body
  – Small electrical current is passed through body
  – Measures resistance to current
     • Fat is poor conductor – 14 to 22% water
     • Lean tissue is good conductor - >90% water
  – Assumes normal hydration
       Body Composition – Other
             Techniques
• Bioelectrical Impedance Analysis (BIA)
  –   Does not require a high degree of technical skill
  –   More comfortable
  –   Requires minimal cooperation
  –   Intrudes less on privacy
     Body Composition – Other
           Techniques
• Dual Energy X-ray Absorptiometry (DEXA)
  – Assess total bone mineral, bone, fat, & lean tissues
  – Uses three component model (fat, solids, water)


• Near-infrared interactance (NIR)
  – Light absorption & reflection
  – Chemical composition of the body
  – Accuracy 4 to 11%
Dual X-Ray Absorptiometry
        Prediction Equations

• Population specific
  – Derived on homogeneous population


• General equations
  – Diverse, heterogeneous samples that account
    for differences in age, sex, race, ethnicity, etc.
           Prediction Equations

• Equation Selection
  – To whom is the equation applicable
  – Was equation developed on an appropriate reference
    model?
  – Was a representative sample studied?
  – How were predictor variables measured?
  – Was the equation cross-validated?
  – Does equation give accurate estimates? (2.5 to 3.5% - %fat)
    (2.5 to 3.5 kg – FFM)

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:65
posted:4/5/2011
language:English
pages:40