Applicability of Ratings of Perceived Exertion as a Measure of Subjective Fatigue in First Responders: An Exploratory Study Original Research
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Keywords
physical energy, mental energy, mood states
Abstract
Introduction: Many researchers use Ratings of Perceived Exertion (RPE) as an indicator of subjective fatigue. Recent findings suggest that energy and fatigue are two distinct unipolar moods.
Methods: Eleven first responders (FR) participated in a 90-minute strenuous exercise battery where they ended the protocol by completing a graded VO2max test where they were asked to perform until volitional fatigue, measured through RPE. Subjective feelings of mental energy (ME) and fatigue (MF) and physical energy (PE) and fatigue (PF) were measured before the beginning of the protocol and right after. Data was not normally distributed and presented in median and interquartile ranges. Spearman correlation coefficients were calculated for RPE, post mood state, and changes in mood states.
Results: Participants’ self-reported RPE at the conclusion of the VO2max test was 18.27 [18.00,19.00]. Post PE (r=-0.012, p=0.97), PF (r=-0.036, p=0.92), ME (r=-0.13, p=0.69), and MF (r=0.43, p=0.19) displayed insignificant correlations with RPE. Similarly, insignificant correlations were observed between changes in PE (r=0.26, p=0.44), PF (r=0.46, p=0.15), ME (r=0.35, p=0.30), MF (r=-0.43, p=0.19), and RPE. Five participants reported an increase in feelings of PE (15.00 [13.00,19.00]) and seven participants reported lower feelings of PF (-12.00 [-19.50,-8.00]) post assessment. Seven participants reported improvements in ME (22.00 [8.00,68.00]) and three reported a reduction in MF (-13.00 [-27.00, -7.00]).
Conclusions: Our findings suggests that self-reported RPE may not be a reliable measure of subjective fatigue in FR populations during acute strenuous exercise. Further our findings support previous work that ME, MF, PE, and PF are four distinct unipolar moods, and researchers seeking to assess fatigue in FR should use RPE with caution as it seems to be a measure of subjective perception of exercise intensity instead of a true measure of subjective fatigue.
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This work is licensed under a Creative Commons Attribution 4.0 International License.
Copyright, 2026 by the authors. This work is licensed under the Creative Commons Attribution 4.0 International License.
Michael Toczko, George Mason University
Sports Medicine Assessment Research & TestingLaboratory; Graduate Researcher
Dr. Ali Boolani, Gatorade Sports Science Institute
Gatorade Sports Science Institute, Senior Principal Investigator
Dr. Joel Martin , George Mason University
Sports Medicine Assessment Research & Testing (SMART) Laboratory; Associate Professor