Reproducibility of Treadmill Exercise Data in Patients with Atrial Fibrillation

Abstract

Serial submaximal treadmill tests are often used to evaluate the efficacy of therapy in patients with atrial fibrillation. Since the response to serial tests can be influenced by a ‘learning phenomenon’, we performed maximal exercise tests on 9 patients (mean age 63 ± 4 years) with chronic atrial fibrillation. Points of analysis for the initial and follow-up treadmill exercise tests were 3 mph/0% grade, the gas exchange anaerobic threshold, and maximal exertion. Significant (p < 0.05) reductions in ventilation (l/min) and oxygen uptake (ml/kg/min) were observed on follow-up at a standard submaximal work load of 3.0 mph/0% grade and at the gas exchange anaerobic threshold. There was no significant alteration in these variables at maximal exertion. A reduction in heart rate was observed throughout exercise during the follow-up test with the most marked reduction (21 beats/min) occurring at 3.0 mph/0% grade. There were no differences in respiratory exchange ratio or systolic blood pressure at any point. The reduction in submaximal heart rate and gas exchange variables without a significant change in these variables at maximal exertion is consistent with a learning effect. Therefore, studies comparing consecutive submaximal exercise test responses in patients with atrial fibrillation can be misleading.

Metabolic equivalents during the 10-m shuttle walking test for post-myocardial infarction patients

“…The second test was used in the analysis, as research has shown a significant “learning effect” after the first test,10 11 which appears to abate after the second test 12 13. Post-MI subjects performed their tests in the Physiotherapy Department at Kent and Canterbury Hospital, UK, and non-cardiac subjects in the BASES-accredited Sport Science Physiology Laboratory at Canterbury Christ Church University, UK.…”

“…Hence, non-cardiac subjects only completed a treadmill test using similar protocol to the SWT. Each subject was familiarised with the test and performed two tests, which should have been sufficient to substantially reduce any learning effect;12 13 the second was used in the analysis. The treadmill and SWT were performed in random order as determined by computer.…”