Assessment of the RPE as a measure of cardiovascular fitness in patients with low back pain

Improving cardiovascular fitness is recognized as an important aspect in the rehabilitation of patients with chronic low back pain. The improvement of cardiovascular fitness relies on an individual exercising at a certain intensity. The Rating of Perceived Exertion (RPE) has been widely accepted as a way to monitor exercise intensity. This study aimed to determine the criterion validity and the test–retest reliability of the RPE in patients with chronic low back pain. In total, 30 subjects with chronic low back pain performed two identical submaximal graded cycle ergometer tests. Heart rate and oxygen consumption were recorded continuously using the Metamax oxygen analyser. Subjects reported RPE scores every minute. Strong correlations were found between the RPE and heart rate and RPE and oxygen consumption. The reliability of the RPE was examined using the Bland and Altman 95% limits of agreement statistical test. There were wide limits of agreement, with subjects' scores varying as much as four points between tests. The findings demonstrated that the RPE is a valid measure to monitor exercise intensity in those patients with chronic low back pain. However, its repeatability is questionable.