part 4 Energy expenditure and fatigue

# part 4 Energy expenditure and fatigue - Lecture 4: Energy...

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Lecture 4: Energy Expenditure and Fatigue How is energy expenditure measured? Why is it important to measure the volume of oxygen and carbon dioxide that is taken up/given off during exercise? What is the respiratory exchange ratio (RER)? How is the RER calculated? How does calculating the RER help determine what energy source is being metabolized? What is the Resting Metabolic Rate (RMR)? What factors affect the RMR? What is the VO2 max? What is the significance of the VO2 max? What factors contribute to fatigue? Measuring Energy Costs of Exercise Direct calorimetry measures the body’s heat production to estimate energy expenditure Indirect calorimetry calculates energy expenditure from the ratio of CO 2 produced to O 2 consumed A Direct Calorimeter for Human Use •Direct calorimetry involves using a large chamber to directly measure heat production by the body

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Indirect calorimetry Indirect calorimetry calculates energy expenditure from the ratio of CO 2 produced to O 2 consumed Equipment Used to Measure O2 Consumption and CO2 Production in the Lab and the Field VO 2 : Volume of oxygen consumed VCO 2 :Volume of carbon dioxide released By calculating these two values, you can indirectly estimate the amount of energy released from carbohydrate and/or fat. Calculating Oxygen Consumption and Carbon Dioxide Production . . Calculating Oxygen Consumption and Carbon Dioxide Production Calculating VO 2 and VCO 2 : Before calculating the VO 2 and VCO 2 , the following measurements need to be determined first Volume of air inspired (V I ) Volume of air expired (V E ) Fraction of O 2 in the inspired air (F I O 2 ) Fraction of CO 2 in the inspired air (F I CO 2 ) Fraction of O 2 in the expired air (F E O 2 ) Fraction of CO 2 in the expired air (F E CO 2 ) . . . .
Calculating VO 2 : Volume of air inspired (V I ) multiplied by the fraction of O 2 in the inspired air (F I O 2 ) gives us the volume of inspired O2 While the Volume of air expired (V E ) multiplied by the fraction of O 2 in the expired air (F E O 2 ) gives us the volume of expired O2 The difference between the volume of inspired and expired O2 is the VO2 . . . . VO 2 = (V I x F I O 2 ) – (V E x F E O 2 ) . . . Calculating VCO 2 : Volume of air inspired (V I ) multiplied by the fraction of CO 2 in the inspired air (F I CO 2 ) gives us the volume of inspired CO2 While the Volume of air expired (V E ) multiplied by the fraction of CO 2 in the expired air (F E CO 2 ) gives us the volume of expired CO 2 The difference between the volume of inspired and

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## part 4 Energy expenditure and fatigue - Lecture 4: Energy...

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