Lecture 4 - Body Composition and Health

Question 1

What is a somatotype?

Answer 1

Body type classification

Question 2

Describe the characteristics of endomorphs in relation to health

Answer 2

– Shortest life span
– Prone to CVD and some postural problems

Question 3

Describe the characteristics of mesomorphs in relation to health

Answer 3

– Cope best with physical work
– Have least postural problems

Question 4

Ectomorphs

Answer 4

– Longest living
– Have most postural problems

Question 5

What is the normal subcutaneous fat stores for male and female

Answer 5

M ~12%; F ~15% BW

Question 6

What percent of BW is essential fat?

Answer 6

3% of BW for M & F (4-7%)

Question 7

What is the additional sex specific fat for females?

Answer 7

5-9% sex-specific fat for females

Question 8

What is a direct way of measuring body composition

Answer 8

Direct measurements only from cadavers

Question 9

What are the ways we can indirectly measure body composition?

Answer 9

• Hydrostatic (underwater) weighing
• Skinfold thicknesses plus formulas
• Girth measurements plus formulas
• Electrical impedance
• Imaging techniques
• Air densitometry

Question 10

Which test is the gold standard of body composition tests?

Answer 10

Hydrostatic Weighing

Question 10

How does hydrostatic weight assess body composition? Describe the expense, reliability, validity and general accuracy

Answer 10

Measures body composition based on the effects of body density on weight measured in water. Expensive, reliable, moderately valid and generally accurate

Question 10

How do imaging techniques assess body composition? Describe the expense, reliability, validity and general accuracy

Answer 10

Utilizes ultrasound, X-ray, CT scan, MRI, or DEXA to assess body composition through imaging. Expensive, reliable, valid and generally accurate

Question 10

How does Air Densitometry (BodPod) assess body composition? Describe the expense, reliability, validity and general accuracy

Answer 10

Measures body mass using air displacement. Moderate for: expensive, reliable, valid and accurate

Question 11

How does Bioelectrical Impedance Methods assess body composition? Describe the expense, reliability, validity and general accuracy

Answer 11

Measures resistance to electrical current flow through body tissues. Low for expense and validity, moderate for reliable and accurate

Question 12

How does skinfold measurements assess body composition? Describe the expense, reliability, validity and general accuracy

Answer 12

Measures subcutaneous skinfold thicknesses using calipers. Cheap and moderate for reliability, validity and accuracy.

Question 13

Regarding bioelectrical impedance methods, how do these methods determine fat and what are these measurements sensitive to?

Answer 13

Fat decreases current flow, results are sensitive to hydration status and skin tempreature

Question 14

What are the limitations to using imaging techniques for body composition assessments?

Answer 14

Limitation(s):
– Expensive
– Exposure to radiation

Question 15

What is the formula to calculate BMI?

Answer 15

BMI = Weight / Height 2 (kg/m2 )

Question 16

How do girth measurements work?

Answer 16

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.

Question 17

What are the 3 components of TDEE?

Answer 17

– Sleeping metabolism
– Basal metabolism
– Arousal metabolism

Question 18

How is TDEE determined during studies?

Answer 18

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

Question 19

How is TDEE normally calculated for general population?

Answer 19

– Calculations based on knowledge obtained from measurements of metabolism and physical activity

Question 20

What is basal metabolic rate defined as?

Answer 20

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

Question 21

What is resting metabolic rate?

Answer 21

Resting metabolic rate is the energy required to maintain vital functions PLUS digestion (i.e., BMR plus digestion)

Question 22

What are the conditions to measuring BMR?

Answer 22

* 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%

Question 23

What is the unit of measurement of BMR when measured at rest?

Answer 23

Relative to body surface area (kJ/m2 /h)

Question 24

What is the unit of measurement of BMR when measured during exercise?

Answer 24

Relative to body weight (kJ/kg/min)

Question 25

What is obligatory thermogenesis?

Answer 25

Energy required to maintain body temperature and for digesting, absorbing and assimilating food

Question 26

What is facultative thermogenesis?

Answer 26

– Thermic effects of activating sympathetic nervous system e.g., when cold – Heat from skeletal muscle activation or brown adipose tissue to maintain body temperature

Question 27

Which macronutrient has the highest thermogenetic effect?

Answer 27

Protein

Question 28

What is 1 MET equal to?

Answer 28

1 MET = resting energy expenditure (~ 3.5 mL O2 consumption/kg/min (2.5-4.5)). Equivalent to sitting quitely

Question 29

What factor more do athletes have than normal people in relation to TDEE?

Answer 29

Endurance athletes may have TDEE double normal person due to training

Question 30

What are the sustainable MET levels for a) most people, and b) endurance athletes

Answer 30

* 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

Question 31

What influences the thermic effect of physical activity?

Answer 31

* Intensity of activity * Duration of activity * Amount of muscle mass activated * Weight-bearing activity * Efficiency (economy of movement)