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Chapter 14 - Sub-maximal Exercise Testing - 129
Considerations for accuracy
The ability to obtain valid and reproducible results is essential to ensure that any
differences between pre-treatment and post-treatment test results are due to exercise
training rather than variations in testing procedures. Some inconsistencies that are
inherent may increase variability:
•
Sub-maximal heart rate is influenced by time of day, eating, smoking, and
familiarization with test procedures.
•
Prediction equations for estimating VO
2max
may overestimate trained individuals
and underestimate untrained individuals.
•
The efficiency of motion during walking, running, and cycling varies.
•
Cardiac output and VO
2
have a test-retest variability of 3-4%.
Psychological factors, such as pre-test anxiety, may influence the heart rate, especially
at rates below 120 beats per minute and at low workloads. It is not unusual for the heart
rate and/or blood pressure to be higher at rest than during the initial stages of exercise in
these cases. Having the subject repeat the first test may improve reliability, particularly
if the subject has never previously performed such a test.
Factors that can cause variation in the heart rate response to testing:
•
Dehydration
•
Prolonged heavy exercise prior to testing
•
Environmental conditions (e.g., heat, humidity, ventilation)
•
Fever
•
Use of alcohol, tobacco, or caffeine 2 to 3 hours prior to testing
Because of these inherent inconsistencies, standard procedures for each test must be
strictly followed to ensure the greatest accuracy and reproducibility possible:
•
Standard testing protocol
•
The same testing modality and protocol for repeat testing
•
A constant pedal speed throughout cycle ergometry testing
•
Cycle seat height properly adjusted, recorded, and standard for each test
•
The time of day for repeat testing consistent
• All data collection procedures standardized and consistent
•
Test conditions standard
•
Subjects free of infection and in normal sinus rhythm
•
Prior to the test, no intense or prolonged exercise for 24 hours, smoking for 2-3
hours, caffeine for 3 hours, or heavy meal for 3 hours
•
Room temperature 18-20°C (64-68°F) with air movement provided