## INTRODUCTION

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 bench stepping, 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 energy expenditure when provided the oxygen uptake in liters per minute or ml · kg−1 · min−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

• Metric System

• SI Units

Work and Power Defined

• Work

• Power

Types of Ergometers

• Bench Step

• Cycle Ergometer

• Arm Ergometer

Measurement of Work and Power

• Bench Step

• Cycle Ergometer

Measurement of Energy Expenditure

• Direct Calorimetry

• Indirect Calorimetry

Common Expressions of Oxygen Consumption and Energy Expenditure

Estimation of Energy Expenditure

Calculation of Exercise Efficiency

• Factors That Influence Exercise Efficiency

Running Economy

Key Terms

arm ergometer

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

How much energy do you expend when you run a mile? How fast can you run 100 meters? 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. Let’s begin with an introduction to 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 system, the basic units of length, volume, and mass are the meter, the liter, and the gram, respectively. The main advantage of the metric system is that subdivisions or multiples of its basic units are expressed in factors of 10 using prefixes attached to the basic unit. Students not familiar with the metric system should refer to Table 1.1 for a list of the basic prefixes used in metric measurements.

TABLE 1.1Common Metric Prefixes

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