The Importance of RPE

Athletic performance is benefitting from an influx of monitoring and testing technologies that allow athletes and coaches to dial in pacing, fueling, and training stress more precisely than ever. A few of the more common technologies we employ here at TriLife Coaching:

-Heart Rate Monitors
-Power Meters (e.g. PowerTap)
-Metabolic, Threshold and Aerobic Capacity Testing (e.g. New Leaf)
-GPS Pace Monitoring (e.g. Garmin)
-Impedence Body Composition Testing

But for all their value, these technologies do not replace the role of Rate of Perceived Exertion (RPE) in athletes' training and racing.

Defining RPE

The are two main scales for measuring RPE - a 9 point (1-10) and 15 point (6-20) - both developed by Borg. These scales are simple ratings of perceived exertion (RPE) used by many coaches and physiologists to assess an athlete’s level of intensity during training or testing sessions.

The 15-point scale is illustrated below as an example: point 6 would be the equivalent of sitting down doing nothing, 9 would be walking gently, 13 a steady exercising pace and 19/20 the hardest exercise you have ever done.

6
7 - Very, very light
8
9 - Very light
10
11 - Fairly light
12
13 - Moderately hard
14
15 - Hard
16
17 - Very hard
18
19 - Very, very hard
20 - Exhaustion

According to a 2002 study in the Journal of Sports Science, a team of Californian researchers found that, to varying degrees across genders and fitness levels, RPE correlated closely with VO2Max, blood lactate levels, heart rate, and MOST closely to ventilatory levels. The 15 point scale was most accurate, however, there was less confusion for athletes using the 9 point scale.

Measuring RPE

That correlation with ventilation, and the importance of having a clear rating system outside of the laboratory for training and racing, led me to develop the following RPE chart for my athletes to use:



I also like this one:



I encourage athletes to use "half-points" to fine tune the 9-point scale, especially at the high end, to differentiate between high/low end tempo and high/low end VO2Max efforts (e.g. start the two minute repeat at an 8.0 and end at a 8.5). This allows for cardiac drift, mental fatigue, and corresponding RPE drift.

In a laboratory or studio setting it is appropriate to use the 15-point scale and post it in front of the athlete so that they can refer to it and use a wider range of values to pinpoint exertion level.

The Appropriate Evolution of RPE in An Athlete's Development

As the study in the Journal of Sports Science found, "accuracy" of RPE is very much driven by fitness level and experience of an athlete. Someone new to running, for example, might identify themselves as at an RPE 8.0 as soon as then cannot speak in long, complete sentences - what an experienced athlete would correlate with an RPE of 5 -simply because they are not familiar with being out of breath and it is unsettling.

As a coach, however, I think this feedback is important and valid. The "downward" adjustment of RPE in less fit individuals helps prevent injuries and burnout. While that person might not progress as quickly in the short term as if they were working "harder", chances are that their progress will be greater over time because their training will progress more consistently. As their fitness improves and their experience working at more difficult intensities accumulates, their RPE:physiological benchmark (ventilation, HR, lactate, VO2Max %) relationship will become more accurate over time.

The Accuracy of RPE versus Data Collection Technology

Coaches often say that the accuracy of a power meter is less important than the precision. What does that mean? It means that the actual number the meter yields is not as important as making sure that the power meter yields the SAME number under the SAME application of force every time.

The opposite would seem to be true for RPE, however, since we can rarely reproduce all of the variables that go into performance output in an individual athlete, RPE can be the most accurate indicator of performance. Why? Because the human body reacts differently under the same application of stress depending upon many outside variables such as heat, humidity, air quality, mental arousal (adrenaline and other endocrine system releases), menstrual cycle, nutritional intake, training stress load, etc., and that reaction at any given moment can make or break a key training session or race.

Think about it this way: if I am time trialing on the ECV time trial course on a cool, cloudy day, I might record an RPE of 8.0 at my threshold watts of 200 and heart rate (HR) of 185 at minute 15. I had a night of good sleep, a day of good nutrition, and a rest day the day before. However, if I am time trialing at an indoor TT the day after being up with a sick child all night, and where the collective work of the participating athletes has driven the temperature and humidity up, and the available oxygen down, I might record an RPE of 9.5 at 200 watts and a HR of 179 at minute 15.

So RPE is less precise than wattage and HR as an instantaneous indicator of performance (speed). HOWEVER, if this is a 30 minute time trial in both cases, it is likely that I can sustain and even build from an RPE of 8.0 over the latter 15 minutes, but less likely that I can sustain or build from a 9.5. So in the first case it is likely that I can hold or even increase my watts towards the finish, whereas my watts are likely to falter pretty soon in the second scenario (I will spit the bit as they say).

If I pay attention only to wattage/HR as an indicator of correct pacing, then in the second scenario I will blow up, whereas I could have corrected for RPE earlier and finished strongly (albeit not as fast as on a day with ideal circumstances). And in the first scenario, I may very well underperform if I stay within wattage and HR zones, when RPE indicates that I could push harder in the latter stages of the race.

The key is monitoring performance and collecting benchmark data and correlating them to a variety of RPEs under different circumstances. Over time, the athlete will begin to understand more closely the variables that affect real and perceived exertion, and will be able to fine-tune their performances as a result. However, without the ability to honestly and accurately assess RPE, the athlete is simply adrift in a sea of data that will not consistently help them improve either their training or racing approaches.