Exercise Testing and Interpretation: A Practical Approach,
C. B. Cooper, T. W. Storer, New York, NY, Cambridge University Press, 2001, soft cover, 278 pp, illustrated, $45
The book is designed for pulmonologists, cardiologists, and sports physicians as well as respiratory therapists and other allied health professionals as a resource for selecting instruments, identifying appropriate test protocols and interpreting physiologic response variables. The book is divided into six chapters and includes five appendices that supply a glossary, calculations and conversions, reference values, protocols, and supplemental materials as well as one titled “Frequently Asked Questions.”
The first chapter, which describes the purpose of the book, indicates that the text is designed to be a practical guide for those involved in exercise testing. The chapter includes a section on basic exercise physiology that illustrates important concepts for the reader. Fundamental to this explanation is the coupling of cellular respiration and cardiovascular and ventilatory processes to external work. A brief description of metabolic pathways involved in cellular energy generation is included and the Krebs cycle and mitochondrial pathway for oxidative phosphorylation are illustrated. The concepts of aerobic and anaerobic metabolism are explained and the threshold between them is briefly discussed and its practical importance emphasized. The processes of cellular energy generation are considered in terms of efficiency and their consequences for the exercise response. Finally, exercise test nomenclature is presented including the two exercise test disciplines: performance exercise testing (PXT) and clinical exercise testing (CXT). The former typically is performed on individuals who are healthy; the latter is performed on those with signs and symptoms of disease. Evaluation of the exercise response is briefly presented and illustrated. The specific applications of exercise testing in assessment of physical fitness, evaluation of exercise tolerance, and differential diagnosis of disease are outlined. Finally, the evaluation of the effectiveness of exercise prescription and other forms of therapeutic interventions are considered.
The second chapter of the book is devoted to a description of instrumentation used in exercise testing. Beginning with an overview of measurement concepts, the authors present brief discussions of validity, calibration of instruments, accuracy, precision (what they define as reliability), and measurement error. The instruments discussed range from indoor and outdoor walking or running courses, to timing devices, ergometers, volume measuring devices (such as gas collection bags), gas analyzers, and metabolic measurement systems ranging from gas mixing chamber systems to electrocardiography and pulse oximetry. In each instance, the authors provide a description of the principles of operating the instrument(s), information regarding calibration, accuracy, and precision as well as maintenance of the instrument.
The third chapter addresses testing methods. This chapter is organized to discriminate between PXT and CXT with regard to issues of importance in each of these testing disciplines. Tables are provided in the chapter that presents the purpose of testing within each discipline, the setting (field or laboratory) and appropriate testing protocols for each purpose in each setting. Performance tests are presented first, with brief discussions of fitness assessment, exercise prescription, and monitoring progress. Descriptions of field tests for performance precede presentation of laboratory tests for performance. Clinical exercise tests are then presented with descriptions of both field and laboratory tests. A section on subject preparation for clinical testing includes information on obtaining a medical history and informed consent. Subsequent sections present the various tasks that precede obtaining data from clinical testing. This section is followed by a discussion of recommendations for the qualifications of personnel administering the tests and supervision of the subject during the testing protocol. The authors make reference to the American College of Sports Medicine guidelines. Data collection procedures are explained, including resting phase, warm-up, the exercise phase and recovery. A brief segment is included on generating reports of the testing, as is a section on methodological issues that could affect the interpretation of the tests. Safety considerations, contraindications to testing and emergency procedures conclude the chapter.
Chapter 4 presents a compendium of exercise response variables. The derivation of the variable is explained along with its significance. Both normal and abnormal values for the variable are presented. This chapter includes information on the following comprehensive list of exercise response variables: endurance time, walking and running distance, six minute walking distance, shuttle test speed, V02max, work efficiency, metabolic, gas exchange, or lactic acid threshold, time constant oxygen uptake, respiratory exchange ratio, muscle respiratory quotient, maximum heart rate, slope of the cardiovascular response, oxygen pulse, electrocardiogram, arteriovenous difference in oxygen content, cardiac output, cardiac stroke volume, systemic arterial pressure, pulmonary arterial pressure, maximum minute ventilation, slope of the ventilatory response, ventilatory threshold, respiratory compensation point, tidal volume, respiratory rate, oxygen breath, ratio of inspiratory to expiratory time, inspiratory and expiratory flow: volume relationships, ventilatory equivalents, arterial blood gas tensions, end tidal gas tensions, alveolar-arterial oxygen partial pressure difference, arterial-end-tidal carbon dioxide partial pressure difference, dead space-tidal volume ratio, lactate, ammonia, rating of perceived exertion, and breathlessness. The discussions of each variable are illustrated as appropriate with graphs of normal and abnormal responses.
Chapter 5 presents the topics of data integration and interpretation. The authors explain that the use of well-calibrated instruments and an appropriate test protocol will lead to one or more measures of the response variables described in Chapter 4. The next step in exercise testing is to integrate and interpret the test findings. The first topic presented in this chapter addresses comparison of the test result with specific reference values. These values include population means, and the use of prediction equations that compensate for variables such as age, gender and body mass. Prediction equations for V02max are referenced and the reader is referred to the Appendix for the equations. Another method of comparison with predicted normal values is the nomogram. Nomograms are graphic portrayals of predicted values; again examples are available in an appendix of the text. Comparisons of a series of values for single variables are used to examine progress of subjects in fitness programs to document response to conditioning or rehabilitation and to monitor the progression or regression of illness. The process of data reduction and portrayal of multiple sets of data is discussed and suggestions given for addressing a set of questions that might be asked about the data. A helpful table is presented to assist the reader with this information. This eight-step process of reducing and preparing the data for presentation is explained in some detail. Tabular and graphic displays are discussed. The same approach to data reduction and presentation is then presented for clinical data gathered on multiple variables. In this instance, diagnostic response patterns are presented and the various conditions that exhibit specific response patterns are presented. The response patterns include: cardiovascular limitation, abnormal cardiovascular response pattern, impaired oxygen delivery, ventilatory limitation, abnormal ventilatory response pattern, abnormal ventilatory control, impaired gas exchange, abnormal muscle metabolism, abnormal symptom perception, and suboptimal effort.
The sixth and final chapter presents a set of six illustrative cases for the reader. Within each case, presentation is a description of the subject along with a statement of the purpose of exercise testing. The testing method is described and the results are presented in both tabular and graphic form. Response variables of import to the case are discussed. A final brief interpretation of the results is included, and a short addendum to each case describes the intervention and result of that intervention. The cases include: declining exercise capacity with a history of asthma in a 51-year-old man; a sedentary young woman who was preparing to begin an exercise program; an apparently healthy 44-year-old man who complained of exertional breathlessness and muscle fatigue; a 71-year-old man who was referred to a pulmonary rehabilitation program; a 58-year-old man with a history of occupational exposure to solvents; and a 65-year-old man with muscle fatigue and breathlessness.
This is a very well-written and comprehensive text on exercise testing. It would be a valuable reference to any therapist or therapy department that conducts or refers clients for exercise testing. The limitation of this work for the pediatric therapist is that reference values are limited to values for teens and adults. It would, however, be a very useful reference for pediatric therapists working with teenage populations. The appendices are particularly useful as a reference for those less familiar with exercise testing protocols.