Ratings of Perceived Exertion Among Standard Treadmill Protocols and Steady State Running

Abstract

The purpose of this study was to determine if differences exist in ratings of perceived exertion (RPE) at a predetermined relative heart rate between two standard treadmill protocols and steady state exercise in a field setting. Thirty healthy male (N=15) and female (N=15) volunteers were maximally tested using the standard Bruce and a modified Balke (3.0 mph with 2.5% grade each two minutes) protocols. Each subject was randomly assigned to one treadmill protocol first, and then completed the second test forty-eight hours later. Within forty-eight hours following the second treadmill test, all subjects completed a field exercise trial consisting of an 800-m run. During the field trial an investigator paced each subject to an individualized target heart rate (75% maximal heart rate reserve) calculated from the treadmill tests. The total exercise time for the field trial was 4:31 ±0:22 and 5:36 ±0:47 min for the males and females, respectively. During the last 50 m of the field trial, RPE values were recorded. Comparisons of the rating of perceived exertion at the target heart rate (RPE at THR) were made using a 2-way (Gender × Trials) ANOVA with repeated measures across trials. There was a significant gender × trials interaction for RPE at THR, with males reporting significantly higher values during the treadmill tests as compared to the females (BRUCE = 13.5 ± 1.6 vs 12.2 ±1.8; BLAKE =15.9 ±2.3 vs 13.7 ±2.4). There was no difference noted between genders for RPE at THR during the field trial. A within-gender analysis of RPE at THR across trials revealed a similar pattern for both males and females: Balke > Bruce > field trial (p < 0.01). The greater RPE at THR seen during the Balke test may be due to: (1) the local fatigue and discomfort associated with the excessive treadmill incline employed during the Balke protocol, (2) the extended period of time necessary to complete a maximal effort during the Balke protocol, and/or (3) the more frequent reporting of RPE during a shorter stage duration test. These data suggest that when testing healthy individuals, for the purpose of providing an exercise prescription, using a treadmill protocol with modest increases in intensity per stage yields greater RPE's at a given heart rate as compared to a more abrupt, non-steady state protocol. In addition, RPE at THR values obtained during a standardized treadmill test may not accurately reflect the perception of effort at the same relative heart rate in the exercise training setting.

Key words

Perception of effort - test protocols - exercise prescription