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This resource provides an in-depth examination of various methods for measuring energy expenditure, including direct and indirect calorimetry, Douglas bags, and breath-by-breath systems. It discusses the advantages of each method, such as the bomb calorimeter for direct measurements and the doubly labeled water technique for long-term assessment. Additionally, it covers the components of energy expenditure, the influence of physiological factors, and the importance of protein oxidation in metabolic calculations. Understanding these methods is crucial for accurately assessing energy needs in diverse populations, including athletes.
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Ex Nutr c3-energy Measuring energy expenditure • Direct calorimetry • Indirect calorimetry • Douglas bag • Breath-by-breath systems
Ex Nutr c3-energy Bomb calorimeter
Ex Nutr c3-energy Bomb calorimeter
Ex Nutr c3-energy Direct calorimetry chamber
Ex Nutr c3-energy Direct calorimetry chamber
Ex Nutr c3-energy Closed circuit method
Ex Nutr c3-energy Closed circuit method
Ex Nutr c3-energy Douglas bags
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
Ex Nutr c3-energy Calculate CHO and fat oxidation rate using VO2 and VCO2 Assume protein oxidation is zero
Ex Nutr c3-energy Adjusted for protein oxidation
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
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
Ex Nutr c3-energy Muscle biopsy
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
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
Ex Nutr c3-energy Components of total energy expenditure
Ex Nutr c3-energy Energy costs of different activities
Ex Nutr c3-energy Energy costs of different activities
Ex Nutr c3-energy Energy costs of different activities
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)
Ex Nutr c3-energy Energy balance in Tour de France
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
Ex Nutr c3-energy International physical activity questionnaire, IPAQ
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
Ex Nutr c3-energy Energy from fat in exercise with different intensities
Ex Nutr c3-energy Fat expenditure in exercise with different intensities
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
Ex Nutr c3-energy A bout of endurance ex on protein turnover: post-ex supplementation
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
Ex Nutr c3-energy Example: 75 kg male runnermaintain weight, 4300 kcal/day
Ex Nutr c3-energy Example - continued
