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Body composition analysis

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Lecture of Body Composition Analysis for Physiotherapy students

Veröffentlicht in: Gesundheit & Medizin
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Body composition analysis

  1. 1. Body Composition Analysis
  2. 2. What is body composition?  Body composition describes the relative proportions of fat, bone and muscles mass in the human body.  Body composition = the body’s relative amounts of fat mass and fat-free mass (bone, water, muscle, connective and organ tissues, teeth)
  3. 3.  Total body fat = Essential Fat + Storage fat  Essential fat – in bone marrow, nervous tissue, organs(Young men – 3-5 % of body mass, Young female – 08 - 12% of body mass)  Storage fat – accumulates in adipose tissue(Young Men- 3% of body mass, Young female – 12% of body mass)  Fat free mass(FFM) = body mass – fat mass
  4. 4.  Essential fat = crucial for normal body functioning  3–5% of total body weight in males  8–12% of total body weight in females  Nonessential fat = adipose tissue
  5. 5. Essential fat  All fat is not bad!!  We need fat for padding of organs, insulation, energy source  There is a minimum amount that we need to function daily = essential fat  Consists of fat stored in major organs, muscles, and central nervous system  Required for normal physiological functioning: reducing essential fat below some minimal amount can impair overall health. Extremes in dieting (and exercise) can reduce essential fat stores)
  6. 6.  Essential fat constitutes about 3% of the total weight in men and 12% in women
  7. 7. Fat-Free Body Mass (FFM) Defined as body mass devoid of all extractable fat Fat mass = Body mass * % body fat Body mass = 75.1 kg Body fat = 23.6% FFM = Body mass - fat mass What is the FFM for this person? Answer: 57.4 kg
  8. 8. Why we need body composition analysis?  Body Composition and analysis provides information (like % of body fat, fat distribution, body segment girth etc.)which are pertinent to athletic performance and for reducing risk factors associated with musculoskeletal injury and disease.  how much fat to lose versus how much muscle to gain?  Health Implications  there is an ideal % fat for health reasons (prevent onset of diabetes, CHD, BP, etc…)
  9. 9. Consequences of too much increased body fat  Increased risk of chronic disease and premature death; associated health problems include  Unhealthy blood fat levels  Impaired heart function  Heart disease and hypertension  Cancer  Impaired immune function  Gallbladder disease  Kidney disease  Skin problems  Sleeping problems
  10. 10.  Obese people are more than three times as likely as nonobese people to develop diabetes  Excess body fat is a key risk factor for the most common type of diabetes  Excess body fat decreases the ability to perform physical activities
  11. 11. Problems Associated with Very Low Levels of Body Fat  Too little body fat is associated with reproductive, circulatory, and immune system disorders  Less than 10–12% for women  Less than 5% for men
  12. 12. Different Levels of BC Measurement
  13. 13. Body Composition Model  Categorized as direct, indirect or doubly indirect methods  Direct method(chemical analysis of whole body or cadaver) is not suitable in the living body.  Indirect method(hydrostatic weighing etc.)  - Component and property based model  Doubly indirect method(skinfolds etc.)
  14. 14. Assessing Body Composition  Height, Weight, BMI  Waist and hip circumference  Hydrodensitometry (hydrostatic weighing)  Air displacement method  Skinfold assessment  Bioelectrical Impedence  CT, PET  MRI and spectroscopy  Dual energy X-ray absorptiometry (DEXA)  Three dimensional scanning
  15. 15. Factors to consider while choosing the technique.  Need of the individual  Purpose of evaluation  Cost of measurement  Equipment needed  Availability of the assessment tools  Training  Advantages vs. disadvantages  Accuracy, reliability and validity
  16. 16. Height   Stadiometer  Subject removes shoes  Stands straight up and heels together  Takes a deep breath and hold it  Stands with head level and looks straight  Consider standard time and monitoring pre activity level • Measured in cms and inches
  17. 17. Body Mass  Best measured on a calibrated scale  Removes excess layer of clothing and shoes  Empty pockets, remove jewelery and mobiles  Consider a standard time  Body weight(pounds) and mass(kilograms) are different terminologies
  18. 18. Body Mass Index   A rough assessment based on the concept that a person’s weight should be proportional to height  Body weight in kilograms is divided by the square of height in meters  Elevated BMI is linked to increased risk of disease, especially if associated with large waist circumference  Poor predictor of body fat  Not useful for resistance-trained population
  19. 19. Waist to Hip Ratio  Indication of the pattern of body fat distribution.  The waist circumference should be measured at the midpoint between the lower margin of the last palpable ribs and the top of the iliac crest, using a stretch‐resistant tape  Should stand with feet close together, arms at the side,should be relaxed, and the measurements should be taken at the end of a normal respiration
  20. 20.  The WHO states that abdominal obesity is defined as a waist-hip ratio above 0.90 for males and above 0.85 for females
  21. 21. Skinfold Thickness  Based on the principle that approximately half of the body’s fatty tissue is directly beneath skin  Reliable measurements of this tissue give a good indication of percent body fat  Skinfold test is done with pressure calipers  Several sites are measured and percent fat is estimated from the sum of the three sites using Tables  All measurements should be taken on the right side of the body
  22. 22. Men Women
  23. 23. Hydrostatic Weighing  Underwater weighing  Most common technique used for decades  A person’s “regular” weight is compared with underwater weight  Fat is more buoyant than lean tissue  Almost all other indirect techniques have been validated against hydrostatic weighing
  24. 24. Dbody = Mbody / Vbody • Involves measuring the density of the athlete’s body • Volume of body can be determined by hydrostatic weighing. • Archimedes principle - an object (or human) immersed in fluid, loses an amount of weight equivalent to the weight of the fluid that is displaced
  25. 25. Density body = Mass/Volume corrected Relative fat = 495/ Density body- 450 Fat mass = (mass × relative fat)/100 Fat free mass = mass – fat mass Volume = Mass – underwater mass Volume corrected for water density : Intestinal gas and RV
  26. 26. Variables needs to known to Use Hydrodensitometry  Residual volume  Density of water  Amount of gas trapped in the gastrointestinal system  Dry body weight  Body weight fully submerged in water
  27. 27. Hydrostatic Weighing Drawbacks  Time consuming  Not feasible to test large number of people  Requires measurement of residual lung volume (if unknown, can be estimated)  Difficult to perform on the aquaphobic
  28. 28. Air Displacement Method  Individual sits inside small chamber  Computerized pressure sensors determine the amount of air displaced by the person  Body volume is calculated by subtracting the air volume with the person inside the chamber from the volume of the empty chamber (air in the lungs is taken into consideration)  Body density and percent body fat are then calculated  BOD –POD device used.
  29. 29. it’s important to wear minimal, form-fitting clothing such as a lycra or swimsuit for accurate result.
  30. 30. Bioelectrical Impedance Analysis (BIA)  BIA is a rapid, non invasive and relatively inexpensive method for evaluating body composition  Sensors are applied to the skin and a weak electrical current is run through the body to estimate body fat, lean body mass, and body water  Based on the principle that fatty tissue is a less- efficient conductor of an electrical current  The easier the conductance, the leaner the individual  Body weight scales with special sensors on the surface may also be used to perform this procedure