1. Measurement of Human Energy Expenditure
Chapter 8
Measurement of Human Energy Expenditure
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

2. Methods of Measuring Body’s Heat Production
Two methods
Direct calorimetry
Indirect calorimetry
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

3. Direct Calorimetry Airflow calorimeter Water flow calorimeter
Temperature change in air that flows through an insulated space × air’s mass and specific heat
Water flow calorimeter
Change in temperature flowing through coils embedded in an environmentally self-contained suit
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

4. Direct Calorimetry Gradient layer calorimetry Storage calorimetry
Measures heat flowing from the subject through a sheet of insulating materials with piping and cooler water on outside
Storage calorimetry
Subject sits in a known mass of water at a constant temperature. Changes in water temperature are measured.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

5. Indirect Calorimetry Closed-circuit spirometry
Subject breathes into a spirometer.
Soda lime is used to absorb carbon dioxide.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

6. Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

7. Indirect Calorimetry Open-circuit spirometry Portable spirometry
Spirometer is small and is carried in a pack.
Air volume is metered.
Sample is collected to measure concentrations of gases.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

8. Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

9. Indirect Calorimetry Bag technique
Air is collected in a large bag (Douglas Bag).
Small sample is measured for gas concentrations.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

10. Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

11. Indirect Calorimetry Computerized instrumentation
Air flow is measured for volume.
Gas analyzers measure concentrations of oxygen and carbon dioxide.
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

12. Doubly Labeled Water Technique
Isotope-based method
Doubly labeled water contains
Oxygen-18 or 18O
Deuterium or 2H
Isotopes consumed in a known volume of water
Isotopes distribute throughout body fluids
Hydrogen leaves body as 2H2O in sweat and urine
Oxygen leaves body as C18O2 or H218O
Estimates total daily energy expenditure
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

13. The Respiratory Quotient (RQ)
RQ = CO2 produced / O2 consumed
RQ for carbohydrate = 1.00
RQ for fat = 0.696
RQ for protein = 0.818
Nonprotein RQ = 0.86
RQ for a mixed diet = 0.82
RQ – assume that oxygen consumption and carbon dioxide production measured at mouth reflect activity in tissues
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

14. Respiratory Exchange Ratio (RER)
Ratio of CO2 produced to O2 consumed
Calculation of RER is the same as RQ
Metabolic calculations
Calculating energy expenditure during exercise
Volume of air
Concentrations of O2 and CO2
Copyright © 2007 Lippincott Williams & Wilkins.
McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition