Exercise is fundamental to human existence. For most men and women exercise is essential for quality of life and for many it is the essence of their livelihood. Some have a competitive instinct for athletic performance in the pursuit of individual human achievement. We now understand that the maintenance of physical fitness throughout life is crucial if we are to remain healthy and live to an advanced age. In these contexts, the assessment of exercise ability is of considerable importance to humanity. Exercise testing becomes the means of assessing ability to perform specific tasks, quantification of athletic performance, diagnosis of disease, assessment of disability, and evaluation of responses to physical training, therapeutic intervention, and rehabilitation.

Recent years have indeed witnessed widespread applications of exercise testing that range from clinical uses in assessing debilitated patients to sports medicine venues and the testing of élite athletes. Some exercise tests are appropriately performed with a minimum of equipment, such as a watch and a measured course. Others involve more sophisticated instrumentation enabling more detailed assessments. Advances in technology have rendered all exercise tests more accessible and more affordable, although not necessarily easier to perform with accuracy and reliability. Wireless heart rate monitors give instantaneous and reliable heart rates in the field or in the laboratory. Bi-directional, light-weight, mass flow sensors have obviated the need for cumbersome valves and tubing and, together with miniaturized and fast-responding gas analyzers, enable the calculation of oxygen uptake with every breath.

Introduction

Proper selection and use of well-calibrated instruments and an appropriate test protocol should produce one or more of the measured variables described in Chapter 4. These variables now require integration, one with another, and meaningful interpretation to complete the purpose of the exercise test.

Some tests, such as field tests, yield one specific measured variable. These variables are typically compared with reference values (so-called predicted normal values) or related to serial measurements for a given individual. They do not necessarily require integration with other results. The interpretation of individual variables has been thoroughly explained in Chapter 4. However, a brief consideration of the derivation and limitations of reference values will now be addressed.

Laboratory exercise tests, notably the maximal incremental work rate protocols, yield an impressive array of data. The results can be bewildering unless organized and interpreted in a systematic manner. This chapter describes how test data can be displayed, in graphical or tabular format, thus enabling the practitioner to evaluate these data systematically and arrive at conclusions that address the specific purpose of the test.

Based on logical data displays of multiple variables, a scheme for the recognition of specific response patterns can be developed. The scheme presented in this chapter acknowledges that clinical exercise testing is often limited in its ability to point to a specific diagnosis. However, for each abnormal response pattern, the implications are discussed and examples of clinical conditions giving rise to that pattern are given.

Introduction

This chapter provides six carefully selected cases which are used to integrate the concepts of test purpose, instrumentation, testing methods, physiological responses, and interpretation of test results that have been developed in Chapters 1–5. These examples are not meant to represent an exhaustive examination of every set of responses that may be seen in clinical or performance exercise testing. Rather, these commonly encountered cases allow the reader to envisage the process of exercise testing leading to its natural conclusion – an interpretation of exercise performance based upon a systematic process of carefully applied methodologies and accurate collection of key response variables. Each case concludes with a brief statement about the outcome following exercise testing.

Case 1: Declining exercise capacity with a history of asthma (CXT: diagnostic)

Purpose

This 51-year-old male complained of declining exercise capacity. He had a history of asthma but normal pulmonary function tests. He used a salmeterol metered-dose inhaler (MDI: 2 puffs twice daily) and fluticasone MDI (2 puffs twice daily). He had never smoked. He was accustomed to running 2–3 miles, 4–5 days per week. A clinical exercise test (CXT) was requested to define his exercise limitations.

Method

A diagnostic exercise test was chosen utilizing a ramp work rate protocol on a cycle ergometer. Based on the initial physical assessment and reported exercise habits, a ramp rate of 30 W·min−1 was chosen. Expired ventilation was measured using a two-way breathing valve and hot wire flow transducer. Therefore, flow–volume loops could not be obtained.

Introduction

The human body is designed for the performance of exercise. Habitual patterns of exercise activity are known to be linked to health, well-being, and risk of disease. In fitness and athletics, exercise capacity is linked to performance and achievement. In clinical medicine, exercise performance is intricately related to functional capacity and quality of life. Hence the importance of exercise testing and interpretation as a means of determining exercise capacity and identifying factors which might limit exercise performance. Exercise professionals, whether concerned with physical fitness and sports or clinical medicine and rehabilitation, should be well versed in methods of exercise testing and interpretation. Hence the need for a practical guide to assist in this undertaking.

A wide variety of methods have evolved for the purpose of assessing exercise capacity and identifying specific limiting factors. Field tests are commonly used in fitness and sports to assess athletic performance, but can be used to assess progress in clinical or rehabilitative settings. Laboratory exercise protocols are also used to assess fitness and are often combined with electrocardiography to diagnose coronary artery disease. Symptom-limited, incremental exercise testing, including measurement of ventilation and gas exchange, has proven to be an important diagnostic, clinical, prescriptive, and rehabilitative tool. These more complex laboratory tests evaluate the integrated human cardiovascular, ventilatory, and musculoskeletal responses to exercise. Whether the assessment is conducted in the field or in the laboratory, all of these exercise tests require careful attention to detail if meaningful information is to be derived.

Introduction

This chapter is a compendium of variables collected during different types of exercise test. Each variable is defined and its derivation and significance explained. For many of the variables, a normal data set is used to illustrate responses to the type of incremental protocol described in Figure 4.4 (A and B). Reference values are given for normal responses and various types of abnormal response are illustrated. The style of symbols used throughout this book is that recommended by the international scientific community. When new symbols are introduced they generally reflect established conventions. Some symbols represent a departure from previous usage but only when it seems necessary based on logic and consistency. A complete list of the recommended symbols can be found in Appendix A along with their definitions.

Variables of the exercise response

Endurance time (t)

Definition, derivation, and units of measurement

Endurance time quantifies exercise duration for defined constant and incremental work rate protocols as well as variable work rates such as walking and running tests. Endurance time represents the total time of exercise excluding the warm-up period and is often used with walking or running distance (dW or dR) to calculate walking or running velocity (see below).

Time is one of the most important primary variables during exercise testing. The units of measurement are minutes or seconds.

Normal response

Constant work rate exercise

Endurance time for constant work rate exercise varies inversely with the percentage of maximum work rate used for that specific mode of exercise.

Introduction

Before exercise tolerance is evaluated, the practitioner must carefully consider a number of factors that will ultimately influence the interpretation of results and ensuing interventions. These include purpose of the test (Chapter 1), key variables required for accurate test interpretation (Chapter 4), and the best test available for the test objectives (Chapter 3). In considering which data will best serve these objectives, the practitioner should select the most appropriate instrumentation available their collection. This chapter presents a number instrumentation options in the context of test purposes and data desired for interpretation. These include relatively simple field tests, submaximal laboratory tests, and maximal effort tests. Details actual application of these instruments will be presented in Chapter 3. Each instrument will be presented with its description and principle of operation followed by methods of calibration, its accuracy, and precision. Maintenance of the instrument is also discussed. This chapter begins with a brief review of important measurement concepts that influence instrument selection. Figure 2.1 illustrates these concepts.

Measurement concepts

Validation

An instrument is thought to be valid if it accurately measures the variable(s) it is said to measure. For example, a heart rate meter is valid if it accurately represents the true value of the heart rate. It is prudent for the practitioner to ensure the accuracy of measurement instruments. This requires periodic validation studies in which the instrument in question is compared against a “gold standard” or reference method in its ability to measure the variable in question.

Introduction

A variety of methods is available for assessing the integrated response to exercise. This chapter presents detailed methodologies for conducting exercise tests where knowledge of this response is important for fitness or risk assessment, diagnostic, prescriptive, or monitoring purposes. As illustrated in Chapter 1, XT is conveniently partitioned into two general disciplines: performance exercise testing (PXT) and clinical exercise testing (CXT). The PXT is typically performed on the well population, often as part of preventive strategies, for health promotion, and to provide guidance for fitness improvement or as a basis for training athletes. The CXT is usually reserved for individuals presenting with signs or symptoms of illness or disease. In both PXT and CXT, the setting for the XT may be in the field or laboratory. The choice of a field or laboratory assessment depends upon the purpose of the test, the need for density, precision, and accuracy of the response variables, and the available instrumentation and personnel. Lastly, the protocol for field or laboratory tests describes how the test is conducted. Table 3.1 identifies several potential purposes within the two PXT and CXT disciplines along with possible settings and protocols. Clearly, some protocols will serve multiple purposes. For example, a maximal cycle ergometer test without arterial blood sampling may be appropriate for PXT fitness assessments, exercise prescription, progress monitoring, or CXT diagnostic exercise assessments, risk assessments, or in monitoring the progress of a patient undergoing rehabilitation.

Standard instructions for the 6-minute walk test

The following or similar narrative should be used prior to the administration of each 6-minute walk test so that every patient receives the same instructions each time the test is administered. The narrative is best recorded on audiotape and played to the subject immediately before every test.

This is a 6-minute walking test. Before you start, please listen carefully to the following instructions. During this test you should try to walk as far as you possibly can in 6 minutes. You can choose your walking pace according to how you feel but try to achieve a steady pace throughout the test. Do not be concerned if you have to slow down or stop to rest. If you do stop to rest, try to start walking again as soon as possible. Remember that the goal of this test is to cover as much distance as possible in 6 minutes. I will start timing your walk as soon as you begin. Please start walking now.

Blood pressure measurement procedures

Subjects should have been allowed to rest (seated, with feet flat on the floor) for at least 5 min before blood pressure measurements are obtained.

1. Obtain measurements with the subject in a relaxed, comfortable position with the arm bare (do not apply the cuff or stethoscope head over clothing).

2. Choose the correct cuff size for the size of the subject's arm.

3. The bladder width should encircle 40% of the circumference of the arm. Table D3 will assist the user in choosing the correct cuV size based on measurement of the subject’s arm circumference.

4. […]