Measurement frequency influences the rating of perceived exertion during sub-maximal treadmill running

To examine the influence of the frequency of measurement on the rating of perceived exertion (RPE) during sub-maximal exercise. On two occasions participants performed 35 min sub-maximal treadmill exercise at the same running speed. In both runs RPE was measured after 5 min. Thereafter, RPE was measured at either 10-min intervals (RPE10 min), or 60-s intervals (RPE60 s) with the order of conditions controlled using a counter-balanced, cross-over design. The heart rate, VO2 and RER were measured throughout each experimental trial. Significant differences in RPE between RPE60 s and RPE10 min were evident at 15, 25 and 35 min of exercise. No differences were evident between conditions in heart rate, VO2 or RER. Differences in RPE between RPE60 s and RPE10 min indicate that the perception of exertion may be influenced by the act of measurement. The elevated RPE in RPE60 s may have been induced by an increased associative attentional focus.