Perceived Exertion: Revisiting the History and Updating the Neurophysiology and the Practical Applications

Abstract

The perceived exertion construct creation is a landmark in exercise physiology and sport science. Obtaining perceived exertion is relatively easy, but practitioners often neglect some critical methodological issues in its assessment. Furthermore, the perceived exertion definition, neurophysiological basis, and practical applications have evolved since the perceived exertion construct's inception. Therefore, we revisit the careful work devoted by Gunnar Borg with psychophysical methods to develop the perceived exertion construct, which resulted in the creation of two scales: the rating of perceived exertion (RPE) and the category-ratio 10 (CR10). We discuss a contemporary definition that considers perceived exertion as a conscious perception of how hard, heavy, and strenuous the exercise is, according to the sense of effort to command the limbs and the feeling of heavy breathing (respiratory effort). Thus, other exercise-evoked sensations would not hinder the reported perceived exertion. We then describe the neurophysiological mechanisms involved in the perceived exertion genesis during exercise, including the influence of the peripheral feedback from the skeletal muscles and the cardiorespiratory system (i.e., afferent feedback) and the influence of efferent copies from the motor command and respiratory drive (i.e., corollary discharges), as well as the interaction between them. We highlight essential details practitioners should consider when using the RPE and CR10 scales, such as the perceived exertion definition, the original scales utilization, and the descriptors anchoring process. Finally, we present how practitioners can use perceived exertion to assess cardiorespiratory fitness, individualize exercise intensity prescription, predict endurance exercise performance, and monitor athletes' responses to physical training.

Keywords: endurance performance; perception of effort; psychophysiology; sports psychology; training monitoring.

Figure 1

Psychophysical relationship between workload during a cycling exercise (physical stimulus) and perceived exertion (perceptual response) of two subjects (continuous black and gray lines). According to the range model proposed by Gunnar Borg, subjects’ maximum perceptual response (R_max) should be equal, despite between-subjects differences in maximal physical stimulus (E_max). Consequently, different absolute physical stimuli (E₁ and E₂) correspond to similar relative perceptual responses (R_1/2). Adapted from Marks, Borg, and Ljunggren [27].

Figure 2

Illustration of the theoretical principle behind the verbal descriptors shifts (dotted lines) from the 21-points and 7-point category scales to the rating of perceived exertion (RPE) and category-ratio 10 (CR10) scales, respectively. Panel (A) shows perceived exertion responses to the 21-point scale (gray line) and the RPE scale (black line) as a function of the physical stimulus intensity. Panel (B) shows perceived exertion responses to the 7-point category scale (gray line) and the CR10 scale (black line) as a function of the physical stimulus intensity. The dot above number 10 represents a number people can choose to quantify maximal exertion. Adapted from Borg [4].

Figure 3

Illustration of the neurophysiological mechanisms underlying the genesis of perceived exertion during exercise.

Figure 4

Illustration of peak exercise intensity (A) and maximum oxygen uptake (B) estimation through perceived exertion measurement during submaximal incremental exercise testing.

Figure 5

Illustration of critical power determination by obtaining the perception of exertion throughout constant load tests in the severe-intensity domain. (A) Shows perceived exertion over time in three constant-load exercise tests. (B) Shows the linear relationship between the power used in the constant-load exercises tests and the rate of perceived exertion increase over time (perceived exertion slope). Critical power is the intercept (arrow) of the linear regression.