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Energy Flashcards

1
Q

Measure energy expenditure: Direct Calorimetry?

A

Calorimeter

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2
Q

Measure energy expenditure: Indirect Calorimetry?

A

Open-circuit Spirometry—>

Portable systems Douglas bag Computerised (breath-breath)

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3
Q

Measure energy expenditure: Stable Isotopes?

A

2H+18O—>

Doubly labelled water (2H2 18O)—>

Ingestion—>

Distribution (5h)—>

Excretion: Urine (2H+18O) + Breath( 18O)

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4
Q

Measure energy expenditure: Prediction Equations

A

Prediction equations

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5
Q

Components of energy expenditure?

A
  1. Basal Metabolic Rate
  2. Thermic Effect of Food
  3. Thermic Effect of Activity
  4. Growth (children, pregnancy)
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6
Q

Basal Metabolic Rate: A measure of an individual’s metabolism in a basal state?

A

– Immediately after waking (awake)

– Lying supine (eg resting),

– Fasted (all food digested/absorbed, eg >12h fast)

– Thermally neutral conditions

– (eg. no other physical or psychological stimulation).

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7
Q

Basal Metabolic Rate: Reflects energy required for:

A

– Breathing / circulation / ion pumps (eg normal bodily functions)

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8
Q

Basal Metabolic Rate: part 3?

A
  • Requires specialist equipment to measure directly
  • Several prediction equations
  • BMR typically accounts for 40-70% energy expenditure.
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9
Q

Resting Metabolic Rate (RMR)?

A
  • Failure to meet above conditions (eg arousal component)

* >BMR by ~10%

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10
Q

RMR in athletes: Background?

A

• Contribution of metabolic rate to total

EE varies depending on activity level.

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11
Q

RMR in athletes: Method?

A
  • 10 female endurance runners v 10 sedentary controls.

* Thermic effect of meal (TEM) and thermic effect of activity (TEA).

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12
Q

RMR in athletes: Conclusion

A

• RMR accounted for 47% of energy expenditure in athletes compared to 61%
in sedentary controls.

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13
Q

Factors that influence BMR: Age?

A
  • Declines by ~1-2% by year from 20 to 70yr

* Linked to muscle loss and brain weight

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14
Q

Factors that influence BMR: Gender?

A
  • Menstrual cycle fluctuations (100 – 300kcal/d)

* Males > Females (body composition)

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15
Q

Factors that influence BMR: Body Size?

A
  • Fat-free mass

* Muscle is very metabolically active

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16
Q

Factors that influence BMR: Exercise?

A
  • Alterations in fat-free mass
  • Muscle damage
  • EPOC (intensity/duration dependent)
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17
Q

Factors that influence BMR: Nutritional Status?

A

• Undernutrition

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18
Q

Factors that influence BMR: Psychological factors?

A

• Anxiety can increase BMR

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19
Q

Factors that influence BMR: Hormonal factors?

A

• Hypothyroidism reduces BMR

20
Q

Factors that influence BMR: Disease/Injury?

A

• Trauma, fever, injury increases BMR

21
Q

Energy Availability: Methods?

A
  • 8 males completed 4 x 9d exercise& diet interventions

* Ex = 3 x 40min cycle/d

22
Q

Energy Availability: Results?

A

• Energy Availability ~30kcal/kg FFM

23
Q

Energy Availability: Conclusion?

A

• Energy balance decreased by 90kcal/d towards zero indicating the slowing of various metabolic processes. This leads to detrimental health affects.

24
Q

Prediction Equation: Method?

A
  1. Harris-Benedict (1919)
  2. Cunningham (1980)
  3. Owen et al (1986, 1987)
  4. Mifflin et al (1990)
  5. WHO (1985)
25
Q

Prediction Equation: Results?

A

• All prediction equations underestimated RMR except for the Cunningham equation (Why do you think this is?)

26
Q

Prediction Equation: Critical Analysis?

A
  • Recognise the limitations of these predictive equations
  • Study population v New population
  • Age, height, weight, FFM, gender
  • Activity (Athletes v sedentary)
27
Q

Components of energy expenditure?

A
  1. Basal Metabolic Rate
  2. Thermic Effect of Food
  3. Thermic Effect of Activity
  4. Growth (children, pregnancy)
28
Q

Thermic Effect of Food?

A
  • The increase in EE above RMR that occurs due to the ingestion of food
  • Typically accounts for 6-10% of daily EE.
  • Includes the energy required for:
  1. Digestion
  2. Absorption
  3. Transport
  4. Metabolism
  5. Storage
29
Q

Thermic Effect of Food: Dietary Factors affecting TEF?

A
  1. Protein
  2. Carbohydrate
  3. Fat
30
Q

Thermic Effect of food: Method?

A
  • PLA meal vs 400kcal meal consisting of CHO, FAT, PRO

* Metabolic Rate - Indirect calorimetry (90min)

31
Q

Thermic Effect of food: Results?

A

• All test meals increased metabolic rate with the greatest seen in protein, then carbohydrate and then fat.

32
Q

Thermic Effect of food: Discussion?

A

• This is a result of the lower energy requirement to store fat as TG, than proteins (synthesis of new AA) and carbohydrate (storage as glycogen)

33
Q

Thermic effect of activity: Physical activity ratio?

A

• Energy cost of activity : BMR

34
Q

Thermic effect of activity: Physical Activity Level?

A
  • Daily total energy expenditure : BMR

* Old method (summed PAR, SPA?)

35
Q

Thermic effect of activity: Metabolic Equivalents (MET’s)?

A

• Work metabolic rate : RMR

• A fixed rate of oxygen consumption assumed to represent that of an adult
measured during supine rest

• 1 MET is equivalent to 3.5ml/kg/min (~1kcal/kg/h)

36
Q

PAL Matrix for EAR: Assumptions in EAR?

A
  • Basal Metabolic Rate

* Schofield et al (1985) Equation

37
Q

PAL Matrix for EAR: Physical Activity Level?

A

• Sleeping
– 8h/24hr

• Occupation
– (7.5h/24h for 5d = 5.5h/7d)

• Non-occupational (10.5h)
– 8.5h x 1.4PAR plus:
– Non-active – 2h at 2PAR
– Mod active – 2h at 3PAR
– Very active – 2h at 4PAR
38
Q

Establishing the EAR?

A

• An EAR is reported for energy, not the RNI as the RNI would represent an excess energy intake for most of the population. Due to a skewed distribution (sedentary) the median, not mean, is used.

39
Q

Establishing the EAR: Calculations?

A

• Derived from doubly labelled water and basal metabolic rate (Henry 2005)

• PAL - 1.49 (25th centile)
– Less active(immobile)

• PAL = 1.63
– Average activity

• PAL = 1.78 (75th centile)
– More active
– (eg those trying to increase activity levels)

40
Q

Establishing the EAR: Considerations - Physical Activity Level?

A
  • +0.15PAL - 30min moderate intensity exercise ≥5d/wk
  • +0.20PAL – 60min brisk walking (4-5mph, daily)
  • +0.30PAL - 60min active sport 5times/wk
  • +0.40PAL – 60min jogging (6mph, daily)
  • +0.60 PAL - 60min of intense aerobic sport 5 times/wk
41
Q

Current Energy Intake & DRV in the UK: Considerations for DRV?

A

• A level to maintain a healthy body mass
in healthy people at their existing levels
of physical activity.

• Recognises overweight/obesity
prevalence

42
Q

Current Energy Intake & DRV in the UK: Current UK Intake?

A
  • Men = 8.88 ± 2.58MJ/d (~2111kcal/d)

* Women = 6.78 ± 1.91MJ/d (~1613kcal/d)

43
Q

Metabolisable energy?

A

Gross Energy: unabsorbed—->

Digestible energy: Incomplete catabolism’s—>

Metabolisable energy

Protein: 5.65kcal/g—>

92%—>

4kcal/g

Fat: 9.40kcal/g—>

95%—>

9kcal/g

Carbohydrates: 4.10kcal/g—>

97%—>

4kcal/g

44
Q

Dietary energy sources: Conversion factors?

A
  • 1 kcal = 4.184kJ

* 1kJ = 0.239kcal

45
Q

Dietary energy sources: Macronutrients?

A
  • Protein – 4kcal/g
  • Carbohydrate – 4kcal/g
  • Fat – 9kcal/g
  • Alcohol – 7kcal/g

Diet and nutrition (8 decks)

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