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A Journal on Internal Medicine and Pharmacology

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Gazzetta Medica Italiana Archivio per le Scienze Mediche 2011 February;170(1):27-32

language: English

Reliability of graded treadmill testing in patients with intermittent claudication

Hodges L. D. 1, Sandercock G. 2, Brodie D. 3

1 Institute of Food, Nutrition and Human Health, Massey University, Private bag 11-222, Palmerston North, New Zealand
2 Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK
3 Research Centre for Society and Health, Buckinghamshire’s New University, Gorelands Lane, Chalfont St Giles, UK


Aim. The purpose of this study was to examine the reliability of maximal walking time (MWT), peak oxygen consumption, maximal heart rate (MHR), respiratory exchange ratio (RER), rating of perceived exertion and claudication pain scale in these patients.
Methods. Eleven patients underwent two graded progressive treadmill exercise tests. The exercise test commenced with an initial speed of 2 mph and a 0% gradient for two min. During subsequent stages the gradient was increased by two percent every two minutes, and the speed kept constant. During each test, patients were instructed to walk for as long as they could endure the pain (maximum walking time). Peak oxygen uptake was assessed on a breath-by-breath basis by online expiratory gas analysis (CardiO2, Medical Graphics Corp., St Paul, MN, USA).
Results. Repeated tests were obtained within 5±3 days. Paired t-tests demonstrated that measurements of peak oxygen consumption, maximal walking time, maximal heart rate, RER, RPE and pain were reproducible between tests. The coefficient of variation and intra-class correlation coefficient values confirmed the reliability. Bland-Altman analysis revealed that peak oxygen consumption varied within 3 mL kg min-1; however, maximum walking distance varied by up to 158 seconds.
Conclusion. The graded exercise test is reliable. It allows differentiation between patients’ walking ability and allows magnitude of improvement to be analysed post intervention. Metabolic measures taken during the test show similar repeatability, giving the clinician confidence in the interpretation of the values.

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