## OBJECTIVES

By studying this chapter, you should be able to do the following:

1. Express work, power, and energy in standardized (SI) units and convert those units to others commonly used in exercise physiology.

2. Give a brief explanation of the procedure used to calculate work performed during step, cycle ergometer, and treadmill exercise.

3. Describe the concept behind the measurement of energy expenditure using (a) direct calorimetry and (b) indirect calorimetry.

4. Calculate the following expressions of energy expenditure when given the oxygen uptake in liters per minute: kcal · min−1, ml · kg−1 · min−1, METs, and kcal · kg−1 · hr−1.

5. Estimate energy expenditure during horizontal treadmill walking and running, and cycle ergometry.

6. Describe the procedure used to calculate net efficiency during steady-state exercise; distinguish efficiency from economy.

## OUTLINE

• Units of Measure 17

• Metric System 17

• SI Units 17

• Work and Power Defined 17

• Work 17

• Power 18

• Measurement of Work and Power 18

• Bench Step 18

• Cycle Ergometer 19

• Measurement of Energy Expenditure 21

• Direct Calorimetry 21

• Indirect Calorimetry 22

• Common Expressions of Energy Expenditure 23

• Estimation of Energy Expenditure 24

• Calculation of Exercise Efficiency 25

• Factors That Influence Exercise Efficiency 26

• Running Economy 27

## KEY TERMS

cycle ergometer

direct calorimetry

ergometer

ergometry

indirect calorimetry

kilocalorie (kcal)

MET (metabolic equivalent)

net efficiency

open-circuit spirometry

power

relative $V˙O2$

System International (SI) units work

## INTRODUCTION

How much energy do you expend when you run a mile? How fast can you run 100 m? How high can you jump? These questions deal with energy, speed, and explosive power—and so will you as you study exercise physiology. Throughout this text, we will discuss such terms as aerobic and anaerobic power, efficiency, work capacity, and energy expenditure. The purpose of this chapter is to introduce you to some of the most common pieces of equipment and measurements linked to these terms. It is very important to understand this information at the outset, as it is used throughout the text. However, the details associated with specific exercise tests for fitness and performance are covered in detail in Chaps. 15 and 20. Let’s begin with the most basic units of measurement.

## UNITS OF MEASURE

### Metric System

In the United States, the English system of measurement remains in common use. In contrast, the metric system, which is used in most countries, is the standard system of measurement for scientists and is used by almost all scientific journals. In the metric ...

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