Measuring energy expenditure

1. Ex Nutr c3-energy Measuring energy expenditure • Direct calorimetry • Indirect calorimetry • Douglas bag • Breath-by-breath systems

2. Ex Nutr c3-energy Bomb calorimeter

3. Ex Nutr c3-energy Bomb calorimeter

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6. Ex Nutr c3-energy Direct calorimetry chamber

7. Ex Nutr c3-energy Direct calorimetry chamber

8. Ex Nutr c3-energy Closed circuit method

9. Ex Nutr c3-energy Closed circuit method

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12. Ex Nutr c3-energy Douglas bags

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14. Ex Nutr c3-energy Indirect calorimetry and substrate utilization • Assume protein is not important energy source • In some extreme conditions, protein may provide up to 15% energy expenditure • Correction for protein oxidation • Protein oxidation estimated from nitrogen content in urine

15. Ex Nutr c3-energy Calculate CHO and fat oxidation rate using VO2 and VCO2 Assume protein oxidation is zero

16. Ex Nutr c3-energy Adjusted for protein oxidation

17. Ex Nutr c3-energy RER vs RQ • Respiratory exchange ratio (RER, or R) measured at mouth does not always reflect oxidation process in cells (respiratory quotient, RQ) • Hyperventilation: excess CO2 expired • Extra excretion of body CO2 stores (HCO3 - in extracellular fluid) • Buffering of H+ • H+ + HCO3 -> H2CO3 < H2O + CO2

18. Ex Nutr c3-energy Doubly labeled water • Administration of bolus dose of 2 stable isotopes of water: 2H2O, H218O • 18O lost in water and as C18O2 • 2H (deuterium 氘), 3H(tritium 氚) lost in water alone • Difference between 2 tracer excretion rates represents CO2 production rate • Unbiased measurement of free-living situation • Relatively long-term (days, weeks) estimation of energy expenditure • Also use H13CO3 • Equilibrium with body’s CO2 pool

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20. Ex Nutr c3-energy Muscle biopsy

21. Ex Nutr c3-energy Other methods in estimating EE • Heart rate monitoring • Require individual relationship between HR, VO2, EE • Accelerometer • 1, 2, or 3 axes • Combine HR monitoring and accelerometer • Activity records • 24 hr, 1 week, or 1 month recall

22. Ex Nutr c3-energy Components of Energy Expenditure • Total energy expenditure = Basal Metabolic Rate (BMR) + TEA+TEF+AT • Basal metabolism: energy expanded during nonactive rest (just waking) • Thermal Effect of Activity (TEA) • Thermal Effect of Food (TEF): associated with consumption of food, digestive, absorption, metabolism • Adaptive Thermogenesis (AT): in response to change in environmental temperature, increase blood flow to skin, shivering • BMR (kcal/kg) varied by %FFM • Highest in infancy, decline with age • Can be estimated by equations

23. Ex Nutr c3-energy Components of total energy expenditure

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29. Ex Nutr c3-energy Energy costs of different activities

30. Ex Nutr c3-energy Energy costs of different activities

31. Ex Nutr c3-energy Energy costs of different activities

32. Ex Nutr c3-energy Upper limits of energy expenditure • Well-trained athletes can expend ~1000 kcal/h for prolonged periods of time • Up to 9000 kcal/d in Tour de France • More than 10000 kcal/d in extreme long-distance running • Energy requirements can be met by most athletes, if well-planned (e.g. 20% CHO solution during exercise)

33. Ex Nutr c3-energy Energy balance in Tour de France

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36. Ex Nutr c3-energy Components of energy expenditure • Resting metabolic rate, basal metabolic rate • Diet-induced thermogenesis, thermic effect of food • Thermic effect of exercise

37. Ex Nutr c3-energy International physical activity questionnaire, IPAQ

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41. Ex Nutr c3-energy Popular fat-buring tricks - 1 • May not useful, depend on exercise type/intensity/duration and individual needs • Carbohydrate tapering: eat high CHO in morning after ex, low CHO remaining the day • Promote recovery of glycogen after exercise • Burn more fat at night and during sleep • Glycogen recovery may take several hours or longer after ex, may insufficient recovery • Cardiomorning: perform endurance ex in morning • Low glycogen before breakfast, more fat burning during ex • Can only perform morning exercise at lower intensity • May not reach maximal fat oxidation

42. Ex Nutr c3-energy Energy from fat in exercise with different intensities

43. Ex Nutr c3-energy Fat expenditure in exercise with different intensities

44. Ex Nutr c3-energy Popular fat-buring tricks - 2 • Afterburn: not eating for several hours after endurance ex • Increase fat oxidation after ex • May induce protein breakdown after strenuous ex • Light ex may not elicit sufficient fat oxidation • Iron the cardio: weight training before endurance ex • Decrease muscle glycogen during weight training, force higher fat oxidation during subsequent endurance ex • Must involve the same muscle groups • Higher intensity of endurance ex may negatively influence effect of resistance training on protein turnover • Heavy endurance training should separate from weight training with the same muscle groups

45. Ex Nutr c3-energy A bout of endurance ex on protein turnover: post-ex supplementation

46. Ex Nutr c3-energy Designing optimal training diet for sport performance • Determine energy expenditure • Set goals for body weight and composition • Set practical goals for distribution of diet energy into CHO, protein, fat • In g/kg BW and en% • Endurance athletes focus more on CHO, power athletes focus more on protein • Distribute energy intake throughout meals and snacks during a day • Timing is important • Special attention to the first meal of the day • Consider time of workout/training/work/class

47. Ex Nutr c3-energy Example: 75 kg male runnermaintain weight, 4300 kcal/day

48. Ex Nutr c3-energy Example - continued