El nacimiento de la Dirección de Inteligencia Nacional, DINA

Multiple personnel are needed to administer maximal exercise testing, with the exact number being determined by the amount of monitoring used. A list of the primary job responsibilities is provided below, with modifications made to reduce the number of staff if less monitoring is performed or if the staff are very experienced and can perform multiple responsibilities during a test.

SUPERVISOR

This person acting as test supervisor will have performed a pretest review of the client’s risk stratification screening information, making sure there are no contraindications for testing. The informed consent document is reviewed again (note: this would have al- ready been completed at the risk stratification screening) and the exercise test proce- dures are outlined. The supervisor should make sure the client understands that al- though the objective is to work to a maximal effort level, the test can be stopped at any time and the staff should be promptly informed if anything unusual is experienced dur- ing the test (particularly symptoms of ischemia such as chest discomfort). An explana- tion of the rating of perceived exertion (RPE) scale should be provided at this time. The supervisor may also perform one of the test technician roles during the test.

TEST MONITORING ROLES

The most commonly monitored variables during the test are the electrocardiogram or other measure of HR, metabolic measurements, blood pressure (BP), perceived exertion, and possibly oxygen saturation. Additionally, the treadmill or cycle ergometer work rates need to be controlled by the staff, or monitored by the staff if controlled by a com- puter program.

The protocol should start with a brief 1- to 2-minute warm-up (treadmill—slow speed of walking; cycle—unloaded pedaling). During this time the staff should be mak- ing sure all equipment is functioning properly and the client is relatively comfortable on the exercise ergometer. When the staff and the client are ready, the protocol begins and the sequence of measures as described in Table 8.2 is performed. To ensure client safety, it is important that all staff observe the client during the test and that one specific staff member is assigned this responsibility as a primary role. In many laboratories, the tech- nician performing the BP measurements will also obtain measures of RPE and become the primary observer and communicator with the client. One staff member is typically in charge of recording data (HR, BP, RPE, symptoms) during the test. The technician monitoring the electrocardiogram, or other monitor of HR, commonly performs this duty. Also, one technician monitors the readings from the metabolic measurements and can control the workload changes during the test. This technician would also be re- sponsible for the pretest calibration of the metabolic cart and the posttest cleaning and sterilization of the mouthpiece and breathing valve used by the client. The staff should provide feedback to the client throughout the test and encourage a maximal effort. Common objective indicators of maximal effort are a respiratory exchange ratio of 1.1, a plateau in V˙O2(no further increase in V˙O2with an increase in work rate), and

achievement of age-predicted maximal HR. Subjective indicators include an RPE of 18, 19, or 20 and the client’s appearance of exhaustion.

MEASURED AND ESTIMATED V.O

To provide the gold standard measure of CRF, the maximal exercise test must include the assessment of V˙O2with a metabolic measurement system. These systems will pro-

vide measures of exercise ventilation and expired concentrations of O2and CO2to de-

rive the measurement of V˙O2. These metabolic measurement systems can also provide a

detailed recording of the responses throughout the test and can be used to provide other data of interest to the client (e.g., ventilatory threshold).

The measurement of V.O2is not always feasible, as metabolic measurement systems

are relatively expensive to purchase and to maintain. These systems also require addi- tional expertise of the personnel operating them and interpreting results. Fortunately, there are methods to predict V.O2maxfrom measurements obtained during a maximal ex-

ercise test.

ESTIMATING V.O2maxFROM EXERCISE TEST TIME

Several research reports have provided regression equations to obtain an estimate of V.O2maxfrom exercise test duration. When using prediction models, it is critical that the

identical protocol be followed for the test, and that the subjects are not allowed to use handrail support during the treadmill test. It is also important to know the general char- acteristics of the population that was assessed in the study. Box 8.3 provides prediction

Prediction of V.O2max from Treadmill Test Time

BRUCE PROTOCOL Healthy persons (3)

V.O2max(mL  kg1 min1) 6.7  2.82 (men  1, women  2)

 0.056 (time in sec) Healthy men and women (n 296)

V.O2max(mL  kg1 min1) 3.814 (time in min)  3.938  4.68 (r  0.87)

(Unpublished data—Ball State University [BSU] Adult Physical Fitness Program) BSU-BRUCE RAMP PROTOCOL (6)

Men and women (n 392)

V.O2max(mL  kg1 min1) 3.9 (time in min)  7.0  3.4 (r  0.93)

BALKE PROTOCOL

Women (n 49)—3.0 mph protocol with 2.5%/3 min (11)

V.O2max(mL  kg1 min1) 0.023 (time in sec)  5.2  2.7 (r  0.94)

Men (n 51)—3.3 mph protocol (10)

V.O2max(mL  kg1 min1) 1.444 (time in min)  14.99  0.025 (r  0.92) BOX 8.3

equations for the Bruce, BSU/Bruce ramp, and Balke-Ware protocols. The reference ta- bles for CRF interpretation (Tables 7.3 and 7.4) also provide an estimate for the modi- fied Balke protocol used at the Cooper Clinic.

ESTIMATING V.O2maxFROM PEAK WORKLOAD

Another approach to obtaining an estimate of V.O2maxis to use the ACSM metabolic cal-

culations. This method is not desirable as the metabolic calculation equations were de- veloped for steady-state submaximal work rates. However, for cycle testing or other treadmill protocols without prediction equations based on test time, they are sometimes used.

INTERPRETATION

As with other measures of HRPF, no national standard has been developed and accepted for interpreting CRF. However, the ACSM has long used the data developed by the Cooper Clinic in Dallas, Texas, as a source for providing interpretations of CRF assessments. These CRF gender-specific charts were provided in Tables 7.3 and 7.4. Similar to the body com- position norms, it is important to recognize that these values are based on the population that has received these measures and are expressed as percentiles, which may limit their usefulness for interpreting test results from populations with different characteristics.

SUMMARY

The gold standard measure of CRF is the maximal exercise test with measurement of ventilation and the concentrations of O2and CO2in the inspired and expired air. Be-

cause of the increased risks for the client to perform this test, the relatively expensive equipment required to obtain the necessary measurements, and the high level of train- ing required of the testing personnel, this procedure is not routinely performed in all HRPF assessment settings. However, fitness professionals working in preventative and rehabilitative exercise programs will often be involved in performing this form of assessment of CRF.

MAXIMAL EXERCISE TESTS