Perceived exertion refers to the subjective appraisal of the effort put forth during exercise. When dealing with subjective qualities, such as exertion, pain, or illness, it can be difficult for one person to accurately assess the perceptions of another. During medical testing and fitness evaluations, however, such communication can become necessary. For this reason, it is often useful to adopt a standardized scale to describe personal perceptions of effort and fatigue. The most common means of expressing perceived exertion is the Borg scale, a graduated rating system ranging from six to 20.
The Borg Ratings of Perceived Exertion (RPE) scale was developed in the 1950s by Swedish Psychologist Gunnar Borg to address the issue of physician-client communication. With the intention of creating an accurate scale that was transferable among a wide variety of individuals and tasks, Borg developed perception scales for both exertion and pain. Today, the Borg RPE scale is widely used among physicians, personal trainers, and rehabilitation professionals to communicate with patients and clients during physical evaluations.
Numbers used in the Borg RPE scale correlate both with heart rate and with a verbal descriptor. In general, the rating of perceived exertion is equal to one-tenth the client's heart rate. At rest, the average heart rate is typically around 70, with a corresponding RPE value of seven. Using the accompanying verbal descriptors, the perceived exertion would be described as 'extremely light.'
At the other end of the scale, a client working hard on a treadmill might have a heart rate of 170. In this case, the corresponding RPE value would be 17, with a verbal descriptor of 'very hard.' The highest level of perceived exertion, a 20, is described as 'maximal exertion,' and is typically only reached under controlled circumstances with very fit individuals. For most training programs, an RPE value of nine to 12 indicates a safe and effective level of intensity.
Ideally, to optimize the accuracy of the RPE scale, early sessions would involve the client and facilitator working together with the assistance of a heart rate monitor. A heart rate monitor provides immediate, accurate, and ongoing feedback regarding exercise intensity, and an RPE scale provides a tool to communicate and categorize personal perceptions that accompany heart rate level. Over time, the client should become comfortable enough with the scale to easily communicate exertion level to the facilitator.
Combining heart rate monitoring with the use of an RPE scale can improve awareness of how the body responds to exercise. Armed with this knowledge, it becomes easier to reach and maintain target workout intensity based on specific goals. More importantly, a concrete understanding of personal exertion limits will reduce the risk of dangers associated with over-exertion during exercise.