ACSM[042-082]

CHAPTER 3 Pre-Exercise Evaluations 53
The determination of the maximal voluntary ventilation (MVV) should also
be obtained during routine spirometric testing (9,13). This measurement can be
used to estimate breathing reserve during maximal exercise. The MVV should be
measured rather than estimated by multiplying the FEV 1 by a constant value, as
is often done in practice (13).
CONTRAINDICATIONS TO EXERCISE TESTING
For certain individuals the risks of exercise testing outweigh the potential benefits.
For these patients it is important to carefully assess risk versus benefit when
deciding whether the exercise test should be performed. Box 3.5 outlines both
absolute and relative contraindications to exercise testing (7). Performing the
pre-exercise test evaluation and the careful review of prior medical history, as
described earlier in this chapter, helps identify potential contraindications and
increases the safety of the exercise test. Patients with absolute contraindications
should not perform exercise tests until such conditions are stabilized or adequately
treated. Patients with relative contraindications may be tested only after
careful evaluation of the risk/benefit ratio. However, it should be emphasized
that contraindications might not apply in certain specific clinical situations, such
as soon after acute myocardial infarction, revascularization procedure, or bypass
surgery or to determine the need for, or benefit of, drug therapy. Finally, conditions
exist that preclude reliable diagnostic ECG information from exercise testing
(e.g., left bundle-branch block, digitalis therapy). The exercise test may still
provide useful information on exercise capacity, dysrhythmias, and hemodynamic
responses to exercise. In these conditions, additional evaluative techniques
such as respiratory gas exchange analyses, echocardiography or nuclear
imaging can be added to the exercise test to improve sensitivity, specificity, and
diagnostic capabilities.
Emergency departments may perform an exercise test on low-risk patients
who present with chest pain (i.e., within 4 to 8 hours) to rule out myocardial
infarction (4,7). Generally, these patients include those who are no longer symptomatic
and who have unremarkable ECGs and no change in serial cardiac
enzymes. However, exercise testing in this setting should be performed only as
part of a carefully constructed patient management protocol and only after
patients have been screened for high-risk features or other indicators for hospital
admission. Table 3.5 is a quick reference source for the time-course of changes
in serum cardiac biomarkers for myocardial damage or necrosis (1).
INFORMED CONSENT
Obtaining adequate informed consent from participants before exercise testing
and participation in an exercise program is an important ethical and legal consideration.
Although the content and extent of consent forms may vary, enough
information must be present in the informed-consent process to ensure that the
participant knows and understands the purposes and risks associated with the