Lecture 4 - Body Composition and Health Flashcards
What is a somatotype?
Body type classification
Describe the characteristics of endomorphs in relation to health
– Shortest life span
– Prone to CVD and some postural problems
Describe the characteristics of mesomorphs in relation to health
– Cope best with physical work
– Have least postural problems
Ectomorphs
– Longest living
– Have most postural problems
What is the normal subcutaneous fat stores for male and female
M ~12%; F ~15% BW
What percent of BW is essential fat?
3% of BW for M & F (4-7%)
What is the additional sex specific fat for females?
5-9% sex-specific fat for females
What is a direct way of measuring body composition
Direct measurements only from cadavers
What are the ways we can indirectly measure body composition?
- Hydrostatic (underwater) weighing
- Skinfold thicknesses plus formulas
- Girth measurements plus formulas
- Electrical impedance
- Imaging techniques
- Air densitometry
Which test is the gold standard of body composition tests?
Hydrostatic Weighing
How does hydrostatic weight assess body composition? Describe the expense, reliability, validity and general accuracy
Measures body composition based on the effects of body density on weight measured in water. Expensive, reliable, moderately valid and generally accurate
How do imaging techniques assess body composition? Describe the expense, reliability, validity and general accuracy
Utilizes ultrasound, X-ray, CT scan, MRI, or DEXA to assess body composition through imaging. Expensive, reliable, valid and generally accurate
How does Air Densitometry (BodPod) assess body composition? Describe the expense, reliability, validity and general accuracy
Measures body mass using air displacement. Moderate for: expensive, reliable, valid and accurate
How does Bioelectrical Impedance Methods assess body composition? Describe the expense, reliability, validity and general accuracy
Measures resistance to electrical current flow through body tissues. Low for expense and validity, moderate for reliable and accurate
How does skinfold measurements assess body composition? Describe the expense, reliability, validity and general accuracy
Measures subcutaneous skinfold thicknesses using calipers. Cheap and moderate for reliability, validity and accuracy.
Regarding bioelectrical impedance methods, how do these methods determine fat and what are these measurements sensitive to?
Fat decreases current flow, results are sensitive to hydration status and skin tempreature
What are the limitations to using imaging techniques for body composition assessments?
Limitation(s):
– Expensive
– Exposure to radiation
What is the formula to calculate BMI?
BMI = Weight / Height 2 (kg/m2 )
How do girth measurements work?
Circumference measurements of six body sites obtained, Equations are age & sex specific, reliable but not accurate with many populations. No clear distinction between fat and muscle.
What are the 3 components of TDEE?
– Sleeping metabolism
– Basal metabolism
– Arousal metabolism
How is TDEE determined during studies?
Can be determined from studies using doubly-labelled water. Usually expensive and impractical unless undertaking studies
– Isotope based method to estimate total daily energy expenditure
How is TDEE normally calculated for general population?
– Calculations based on knowledge obtained from measurements of metabolism and physical activity
What is basal metabolic rate defined as?
Basal metabolic rate is the minimal energy needed to maintain vital functions in the AWAKE state. Basal metabolic rate is measured under very specific standardised conditions
What is resting metabolic rate?
Resting metabolic rate is the energy required to maintain vital functions PLUS digestion (i.e., BMR plus digestion)
What are the conditions to measuring BMR?
- After a 12 hour fast and restful night’s sleep
- Awake for 30-60 minutes and resting
- No exercise since waking
- Environment:
– Temperature ~ 25o C
– Barometric Pressure ~ sea level
– Humidity ~ 50%
What is the unit of measurement of BMR when measured at rest?
Relative to body surface area (kJ/m2 /h)
What is the unit of measurement of BMR when measured during exercise?
Relative to body weight (kJ/kg/min)
What is obligatory thermogenesis?
Energy required to maintain body temperature and for digesting, absorbing and assimilating food
What is facultative thermogenesis?
– Thermic effects of activating sympathetic nervous system e.g., when cold
– Heat from skeletal muscle activation or brown adipose tissue to maintain body
temperature
Which macronutrient has the highest thermogenetic effect?
Protein
What is 1 MET equal to?
1 MET = resting energy expenditure (~ 3.5 mL O2 consumption/kg/min (2.5-4.5)). Equivalent to sitting quitely
What factor more do athletes have than normal people in relation to TDEE?
Endurance athletes may have TDEE double normal person due to training
What are the sustainable MET levels for a) most people, and b) endurance athletes
- Most people can sustain PA levels 5 X RMR (5 METs)
- Most people should be able to sustain PA levels 10 X RMR
- Elite endurance athletes able to sustain PA levels 20 X RMR
What influences the thermic effect of physical activity?
- Intensity of activity
- Duration of activity
- Amount of muscle mass activated
- Weight-bearing activity
- Efficiency (economy of movement)
