Woman Runner Taking Break Based On Her Rate Of Perceived Exertion

The Basis of RPE and Why Coaches Should Use It

BY Fabiano C. Araujo

Metrics from devices like power, heart rate and HRV are great, but rate of perceived exertion is a powerful tool that coaches shouldn't ignore. Understand its origin and how to apply the scale properly.

When planning workouts to build fitness, a combination of variables comes into play. Sport type, how often, how long, and how hard to push yourself are all important factors to consider. It can all get a little overwhelming, especially if it’s your first time building a training block. 

The three biggest factors to consider are frequency, duration, and intensity. The number of times workouts within a week (or even a single day) is frequency. How much time is spent during each workout is duration, and intensity is the amount of effort.

Frequency and duration are easy to measure, but intensity can be a little tricky. Some people measure it by comparing performance to physiological metrics, like max heart rate or VO2 max. Other people focus on specific performance markers where the body must respond in certain ways, like functional threshold power or the lactate threshold.

One great way to measure intensity is by using a scale called perceived exertion (PE). The two most widely used PE scales were developed by Gunnar Borg a few decades ago. One is the Borg RPE scale, with scores ranging from 6 to 20, and the other is the Borg CR10 Scale, with scores of 0 to 10. 

Understanding and using either the Borg RPE or CR10 Scale provides powerful insights about your athlete’s training that will help you fine-tune future workouts that hit the sweet spot.

The Difference Between the Borg RPE Scale and Borg CR10 Scale

Borg RPE Scale

The Borg RPE Scale was developed by Swedish researcher Gunnar Borg in 1962 as a way for athletes to measure intensity during their workouts. At that time, personal HR straps or smartwatches weren’t widely available, so the scale was based on a high linear correlation between the ratings of perceived exertion and HR (r = 0.85), with the work intensity varying from light to heavy. This scale ranged from 6 to 20, with 6 being no effort at all, and 20 being maximal effort.

Gunnar Borg Rpe Scale
Borg RPE Scale; linear distribution of the scores.

Borg constructed the RPE scale to follow HR for work on the bicycle ergometer in healthy middle-aged men, with HR being about ten times the RPE value. Later, Borg (1974) noticed that the correlation wasn’t as high for other subject groups, such as older people and patients in rehabilitation. That opened the room for the CR10 scale.

Correlation Power Heart Rate
Linear correlation between power and heart rate on the Borg RPE Scale

Borg CR10 Scale

The second RPE scale is the Borg CR10 scale (Image 3), where CR stands for category-ratio, and it considers other variables (e.g., pain perception or blood lactate) that follow positively accelerating power functions (Image 4) with exponents of about 1.6-2, as Borg explains in a 1985 article. In 1998, Borg noted that perceived effort increases with power, but other physiological variables (e.g., sensations from working muscles, joints, skin, and the cardiovascular and respiratory systems) also affect perceived effort. Therefore, a compelling prediction value of perceived effort was available from increased heart rate and blood lactate function.

Borg Cr10 Scale Rpe
Borg CR10 Scale; exponential distribution of the scores.
Correlation Lactate Intensity
Exponential correlation between power and lactate

Using RPE Scales in Training

Both the RPE and CR10 scale can guide your training regimen, aiding in the correlation of perceived effort scores with metrics like power, pace, or heart rate zones (as outlined in Table 1). It’s crucial to recognize that the perceived effort associated with an equivalent level of effort can vary based on many factors, such as your fitness and fatigue levels, environmental conditions (such as cold versus hot, dry versus humid), injury/illness, and your state of recovery. 

Lastly, it’s important to bear in mind that your PE scores might differ from others during workouts or intervals that require similar relative effort levels (e.g., percentage of FTP). This variance boils down to perception, underlining the subjective nature of the experience.

Proposed CR10 scores for endurance training zones:

ZoneCR10 score
Tempo / Sweet Spot3-4
VO2 max6-7
Anaerobic capacity7-8
Neuromuscular power9-10

TrainingPeaks Workout Card PE Slider and Examples

TrainingPeaks web and mobile apps offer a PE slider to help you track your workout scores. You should bear the habit of setting it immediately after completing your workouts. As you build your PE history, it becomes a robust database to track changes in performance or how your cardiovascular system is recovering. 

Instances where there are differences between what was planned and what was actually accomplished hold significant value when it comes to refining your training regimen, programming performance assessments, or engaging in discussions with your athlete.

A prevalent error in training that often results in performance plateaus is the misjudgment of training zones, either by underestimating or overestimating them. This common misstep can hinder progress significantly. 

However, there’s a remedy that can yield positive results: PE scores. When consistently tracked, PE scores serve as an excellent tool for monitoring shifts in performance and overall health status, particularly when comparing different rounds of performance tests.

The Value of PE Scales as a Coach

I prioritize the integration of PE scores in my weekly training plans. Each session or interval within these plans is accompanied by an anticipated PE score. This approach fosters a proactive engagement with my athletes, encouraging them to share their post-workout PE scores and provide any associated comments. By actively seeking this feedback, I gain valuable insights into my athletes’ training experiences and how they align with the expected PE scores.

When disparities emerge between the projected and reported PE scores, it triggers a collaborative investigation. Our focus shifts to identifying the root causes behind the differences. Is the issue related to workout intensity, recovery, or perhaps external factors influencing their perceived effort? Through this thorough exploration, you can make informed adjustments to the training regimen, ensuring it remains tailored to individual requirements.

Indoor training can also introduce a notable source of disparity in PE scores. The majority of athletes rely on the power meter integrated into their indoor trainer to gauge power levels during indoor sessions, whereas they turn to their bike power meter for outdoor rides. Discrepancies of up to 10% in power measurements between these two power meters are not uncommon, particularly when considering factors such as single-sided power models or devices located at varying points on the bike (e.g., rear hub versus pedals).

Given these potential variations, athletes often encounter significant deviations in PE scores while attempting to meet identical power targets. Once again, this becomes a critical observation that prompts a comprehensive approach. It leads to the necessity of conducting tests to validate the observed differences. Subsequently, correction factors can be established to enhance execution precision and foster advancements in fitness levels.

PE proves to be an effective approach for those who prefer not to continually fixate on their bike head units or smartwatches. Assessing intensity during workouts or intervals is often challenging and potentially even risky, especially for novice athletes. Maintaining a constant gaze on a device screen while exercising isn’t safe. Therefore, tell your athletes to take the opportunity to “calibrate” their minds across various training segments, encompassing different levels of intensity and varying training conditions.

The mind functions as a potent processor, capable of comprehending and interpreting an array of input signals. As you and your athletes become more adept at handling these multifaceted variables, encompassing those originating from the body and bike sensors, you’ll refine the ability to deliver peak performances during pivotal events. 

The recent time trial achievement of Jonas Vingegaard, triumphant in the 2023 Tour de France, stands as a compelling illustration of a professional tour athlete leveraging his training expertise to attain an exceptional performance. He adeptly navigated without being overly dependent on the numerical data displayed on his bike computer, instead channeling his effort through his perceived exertion (RPE).


Borg, G. (1998). Borg’s perceived exertion and pain scales. Retrieved from https://psycnet.apa.org/record/1998-07179-000

Borg, G., et al. (1985). The increase of perceived exertion, aches and pain in the legs, heart rate and blood lactate during exercise on a bicycle ergometer. Retrieved from https://pubmed.ncbi.nlm.nih.gov/4065121/

Borg, G. & Dahlstrom, H. (1962, August) The Reliability and Validity of a Physical Work Test. Retrieved from https://pubmed.ncbi.nlm.nih.gov/13871282/

Borg, G. & Noble, B. (1974, January). Perceived exertion. Retrieved from https://pubmed.ncbi.nlm.nih.gov/4466663/

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Fabiano Araujo Bio Photo
About Fabiano C. Araujo

Fabiano C. Araujo, MD, Ph.D., is a board-certified sports medicine physician with 15+ years of clinical and endurance coaching experience and data science. He’s a USA Cycling level 1 coach and part of the Empirical Cycling coaches’ team. He has also been serving TrainingPeaks as a coach educator and SweatID as a scientific advisor since 2017. Contact him at: https://www.empiricalcycling.com/about-our-coaches.html

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