lectures 3-4 Flashcards
Body Composition Models
Anatomical or Fluid/Mineral
- 2-compartment Model
- FM
- LBM (FFM)
why is body comositon useful
- Sport Science
- Determine competition or race weight
- Assess & monitor growing athletes
- Monitor the effect of change to diet & exercise
- Medicine & public health
- Epidemiology of disease & body composition
- Detect atypical growth due to disease, eating
disorder, malnutrition - Concept of ideal body weight
- Child health, growth & development
Factors Affecting Body Comp
- genetic
- hormonal
- environmental
what is body fat for
Insulation
Thermogenesis
Energy
Skeletal tissue
Longitudinal skeletal growth has usually been completed by early adulthood Bones adapt to stress by increasing or decreasing Width Mineral density Architecture Skeletal mass accounts for ~23% of total mass in the adult
The effect of aging and fat and muscle
Fat levels tend to rise in both men &
women
Skeletal muscle & bone mass show an
age related decline (sarcopenia)
‘poverty of the flesh”
Reduction of LBM that appears to
accompany aging
why does age effect ageing
Reduced testosterone & HGH
Reduced physical activity
Malnutrition
Smoking
Assessing body composition
3 Levels Level 1 – Direct Level 2 – Indirect Level 3 – Doubly Indirect ○ (Martin & Drinkwater 1995)
Level 1 - Direct Assessment
Cadaver analysis – Anatomical Dissection Chemical: Fat Nitrogen Water Minerals Surface anatomy followed by dissection of each cadaver into gross tissue weights Anatomical: Skin Adipose tissue Muscle Bone Residual Results used to Develop new anatomically based models Test existing 2-compartment models
Level 2 - Indirect Assessment
Weight for height indices Hydrodensitometry Skinfolds Tissue fractionation Other techniques
Level 3 – Doubly Indirect
% body fat from Skinfolds Hydrodensitometry TOBEC BIA
Weight for height indices
Level 2 - Indirect Assessment
A measure of ‘ponderosity’ & often
incorrectly construed as ‘adiposity’
• BMI (W/H2) & Inverse ponderal Index (W/H1/3)
- Falsely assume any increase in weight beyond the normal/optimal level has to be
attributed to body fat!
Weight for height indices why is it used
Epidemiological validity ○ high correlation with adiposity in studies using large cross sectional samples Precision & reliability Ease of measurement Patient comfort
Hydrodensitometry - Level 2 - Indirect Assessment
- Measure body weight
Measure weight in water
Determine body density
skinfolds: Level 2 - Indirect Assessment
Measure compressed thickness of a double
layer of skin & subcutaneous tissue
Minimum 6 sites