Borg, G. (1985). An introduction to Borg's RPE-scale. Ithaca, NY: Mouvement Publications.

Humans have a very well-developed capacity to assess the level of exertion. Associated feelings provide essential information that is important for determining the welfare or extent of threat to an individual. The perception of exertion is a monitoring behavior that uses all sources of information to govern actions that can benefit or preserve health and partake of adaptive pursuits.

How one feels about exertion moderates the response to exercise and effort. Taylor (1979) has shown that when one exercises with a "positive" attitude the efficiency of physiological function is optimal. However, when the attitude is "negative" that efficiency is reduced. Thus, the perception of what is happening in exercise, and its concomitant effect on physiological function, needs to be known to further understand the nature of an exercise response. How one feels modifies reactions to exercise stress and the mechanisms that underlie them.

Among many of today's sport scientists, there is an opinion that physical strain does not involve any psychological factors. An emphasis on solely measuring physiological exercise parameters is used as the basis for "understanding" exercise responses and for prescribing future activity or training programs. This is a false stance. Exercise is never a purely mechanistic physiological reaction. The interpretation of the exercise experience governs the nature, quality, and extent of the exercise response. To fully understand and accurately assess the nature of an exercise behavior, it is necessary to measure as many moderating variables as possible.

Physiological measures can be used to grade the strain for each individual, but so can exertion estimates. In an exercise response, the underlying determining mechanism may not be the "pure" physiological parameter being measured. Without knowledge of the psychological moderator variables, the physiological measure alone would be misleading. Its value as a predictor variable usually would be negligible. The particular circumstances in which the physiological measure is taken may be more important for predicting or analyzing a response than the variable itself.

To exercise only according to heart rate is dangerous. The aches and strain that are felt may be very important indicators of the real degree of exertive strain. The rigid adherence to the "objective" measures of physiology may cause interpretive and prescriptive errors of a large magnitude.

In many circumstances, the psychological components of an exercise response are more reliable and relevant than physiological measures. For example, that has been shown to be true in the case of long-term exercise strain for determining the early symptoms of the onset of overtraining or maladaptation.

Borg's Ratings of Perceived Exertion (RPE)

Borg's original intention was to construct a category scale from 6 to 20 where scale levels were roughly one tenth of the heart rate for equivalent scaled exercise levels. A score of 6 ("no exertion at all") should exhibit a heart rate somewhere in the vicinity of 60 bpm for a young to middle-aged mildly fit individual. This correspondence is generally reserved for middle-aged people exercising at moderate to high intensity levels. It is, at best, a very rough estimation of the relationship. Large individual differences exist. Also, heart rate - RPE correspondences within an individual vary between different forms of activity. RPE is best reserved for intraindividual comparisons for a specific form of exercise.

Heart rates are related linearly to the scale scores (r = .8 to .9). However, even with this relationship one cannot conclude that heart rate is a cause of the perceived exertion.

The perception of exertion integrates many more exercise factors than are considered with singular or isolated physiological variables. That integration is a truer indication of an exercise response than is depicted by restricted variables such as heart rates, lactate measures, or blood measures.

To understand a certain RPE value it is important to know the age and other personal characteristics of the individual, what kind of activity was performed, and the environmental conditions that existed at the time.

The instructions for using the scale are to "estimate how hard and strenuous you feel the work to be". The perception should be general rather than focusing on specific parts of the body (e.g., tired arms). The perception of exertion should include as many contributory sensations as possible.

Once the verbal description is determined, the individual should choose an exact number when two correspond to the same descriptor. When a subject is unable to complete the highest work load, the rating should be of the work at the time of the final interruption.

With athletes, the major problem with using RPE is the frequent tendency to underestimate the exertion level. Practice in using the scale is necessary. If the various categories can be aligned with different categories or levels of work response, an accurate discrimination between the categories can be developed.

RPE gives important additional data above that which is available through isolated physiological variables. In conscientious and reliable individuals, its value exceeds that of singular parameters of performance.

Instructions for Use

"During the exercise you are to rate your perception of exertion. Use this scale where 6 means no exertion at all and 20 means a totally maximum effort. The 13 on the scale is a somewhat heavy exercise but capable of being performed at steady state (i.e., anaerobic threshold). When at a level of 17 the effort level requires you to push yourself hard even though it is possible to continue for some time. For many people 19 is about as strenuous as exercise becomes because they often reserve a small amount of possible extra effort.

Try to appraise the feeling of exertion as honestly as possible. Do not underestimate nor overestimate it. It is of no value to underestimate the level to produce an impression of being "brave" or "tough". Your own feeling of effort and exertion is all that is of interest. Look at the scale and wordings and decide on the word that best describes your effort level and the number alternative associated with that description.

The Scale As Revised by Rushall

6      No exertion at all
7-8    Extremely light (very, very light)
9-10   Very light  [A1 warm-up/recovery]
11     Light [A2 aerobic threshold]
12-13  Moderate [EN-1 anaerobic threshold]
14-15  Hard [EN-2 VO2max or 400 m swimming pace]
16-17  Very hard [AN-1 peak lactate or lactate tolerance - 200 m swimming
       pace]
18-19  Extremely hard (very, very hard) [AN-2 anaerobic power - 25-50 m 
       pace]
20     Maximum all-out effort with absolutely nothing being held in 
       reserve.

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