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Click to edit Master subtitle style Ch. 4: Measurement of Energy
Why measure Energy Expenditure (EE)?
By measuring or estimating EE, health and fitness professionals will be able to:
1)
2) 3) 4)
Prescribe appropriate _____ and _____ exercise to induce training adaptations and/or to manage body weight. Monitor improvement in ... Determine ... Calculate ...
How can EE be measured?
Direct Calorimetry
EE is determined from the amount of heat produced by the body. What is a calorie?
How else can EE be measured?
I ndirect Calorimetry
Calculates EE from the amount of _________ and __________. Based on the principle that VO2 and EE share a ________ relationship.
VO2 (L.min-1)
3 2.5 2 1.5 1 0.5 0 1 3 Treadmill Speed (mph) 5 7
Indirect Calorimetry
What does indirect calorimetry measure?
VO2 can be used to ...
Thus, EE can be expressed in what 4 ways?
Caloric Rate (kcals/min) Absolute VO2 (LO2 /min) Relative VO2 (mlsO2/kg * min) METS (Metabolic Equivalents)
Example 1
On average, how much oxygen (in relative terms) does an individual consume at rest (i.e., to sustain life)?
For a 160-lb male, what is his resting VO2 in absolute terms?
Example 2
On average, how much calories are expended for every liter of oxygen consumed?
For a 160-lb male, what is his resting rate of energy expenditure?
Example 3
1 metabolic equivalent is equal to what relative VO2?
For a 160-lb male, what is his resting MET level?
Example 4
Fact: l Exercising at 3 to 6 METs is considered exercising at moderate intensity. Question: l If a 175-lb male is exercising at 3 METs, then he is exercising at what Relative VO2? Absolute VO2? Caloric rate (i.e., rate of energy expenditure)?
Example 5
Suppose a 135-lb female performed a bout of exercise that required her to consume, on average, 2.6 LO2min-1. Convert her absolute VO2 in LO2min-1 to: 1) relative VO2 in mlO2kg-1min-1, 2) rate of EE, and 3) Mets.
Indirect Calorimetry
Recall, what does indirect calorimetry measure?
VO2 can be used to
l
1 L of O2 consumed is equal to approximately how many kCal expended?
What a is minor problem with this method of estimation?
Math Problem
Eric jogged for 20 minutes. His average VO2 was 2.33 LO2min-1. How many calories did he expend during this bout of exercise?
As exercise workload increases, what happens to the following?
l
VO2 increases, decreases, or stays the same?
l
Heat production increases, decreases, or stays the same?
l
VCO2 increases, decreases, or stays the same?
l
EE increases, decreases, or stays the same??
Indirect Calorimetry
Can provide a more exact estimate of EE if r espiratory quotient (RQ) is calculated. What is RQ? l the ratio of VCO2 production to VO2 consumption
RQ
Based on the principle that fats and carbs have different chemical compositions. l When fats are broken down, _____ CO2 is produced relative to the amount of O2 consumed l When carbs are broken down, _____ CO2 is produced relative to the amount of O2 consumed Thus, when compared to carbohydrate breakdown, fat breakdown will result in a lower or higher RQ?
What can RQ be used to determine?
The precise number of calories expended per L of O2 consumed The percent contribution of fat and carbohydrates The Intensity of Exercise
What terms are often used instead of RQ?
________________
l
Because proteins contribution to ATP production is minimal.
_______________
Because pulmonary gas exchange does not always exactly reflect cellular gas exchange. l This term should be used under what conditions? ________________
Math Problem
Suppose a female subject performed a 30-minute bout of steady-state exercise. Her average VCO2 was 2.o9 LCO2min-1 and average VO2 was 2.19 LO2min-1. Calculate her RQ and answer the following questions: 1) How much total energy did she expend?; 2) What percent of her calories were derived from fat?; 3) How many calories were derived from fat?
Todays Lab Activities:
Chapter 4 Review Questions Chapter 4 Practice Problems Lab Activity 4-1, Measurement of Energy Expenditure During Exercise
Homework
l
l l
Complete Review Questions, Practice Problems and lab activity 41. Take Chapter 4 post-lab quiz. Read chapter 5.