Chapter 8

1. Chapter 8 Measurement of Human Energy Expenditure McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

2. Methods of Measuring Body’sHeat Production Two methods • Direct calorimetry • Indirect calorimetry McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

3. Direct Calorimetry • Airflow 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 McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

4. Direct Calorimetry • Gradient layer 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. 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. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

6. 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. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

8. 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. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

10. 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. 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 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 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 McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition