Cardiopulmonary Test-Retest Variability in Healthy, Physically Active Women

The reliability of cardiopulmonary values during serial exercise testing has been examined in healthy subjects and in pathological conditions. Three to four percent variability between tests may be attributed to biological factors and up to 8% variability is considered to be acceptable within pathological populations. In a recent study in our lab, patients with Chronic Fatigue Syndrome (CFS) showed variability scores of up to 27% on repeated exercise tests. In other studies repeated tests were done with several days in between, so that it is not known if exercise tests can be reproduced within 24 hours. PURPOSE: The purpose of this study was to establish the degree of variability among cardiopulmonary measures during an exercise test-retest paradigm in healthy, physically active women, with the exercise test separated by 24 hours. METHODS: Six (n=6) physically active women performed two graded exercise tests to maximal exertion on a bicycle ergometer. The tests were separated by 24 hours. Peak values for heart rate (HRmax), oxygen consumption (VO2 max), ventilation (VEmax), respiratory quotient (RQ) and values at anaerobic threshold (AT); HR@AT, VO2@AT, and VE@AT, were compared between test 1 and test 2. Maximal effort was determined using American College of Sports Medicine guidelines. RESULTS: All six subjects reached criteria for maximal effort on test 1 and test 2. Percent variability for each value is shown below: Variability for all factors except oxygen consumption at anaerobic threshold (VO2@AT) were similar to reported values for pathological populations and were similar to the variability reported for sedentary populations. CONCLUSIONS: Within this small group of subjects, test-retest was very small, less than 3% for the majority of the measures. The large variability observed for VO2@AT may be due to methodological error that we will address in follow-up studies