In my post last week on HRMs, I commented that I like to use rating of perceived exertion (RPE) regardless of the devices that I use with my clients (or myself).
RPE is a subjective assessment of how you feel during exercise. It takes into account the whole-body experience and not just the legs (since I am a runner and coach runners, I tend to focus on the legs). While running, I am assessing how my legs feel along with my breathing and any sensations elsewhere. I like RPE because it takes into account my whole body. A HRM only measures how fast my heart is beating. A GPS only measures how fast (or slow) I am moving (okay changes in elevation too).
Yes, RPE is subjective, but I believe it is still very useful. If a runner is using a HRM but is having difficulty maintaining the intensity needed, RPE can tell us that the effort was harder than expected or harder than in the past. We can then look for reasons why that might be the case. Was the terrain hillier or more technical (or the trail runners) than usual? Was the temperature warmer than normal? Did the person have a bad day at workout?
In an effort to quantify RPE, we use a numbered scale that has specific descriptions that go with each rating number. There are two commonly used scales. The Borg scale (take it easy Star Trek: TNG fans) rates the effort from 6 to 20. The modified Borg scale (and it has nothing to do with the great tennis player either) goes from 0 to 10. (The hyperlinks will take you to pages that give the verbal descriptions.)
I have found that people are very consistent in their ratings. When I worked at the US Olympic Training Center in Colorado Springs, CO, we tested some athletes multiple times using metabolic carts and measuring blood lactate levels. Each time we also monitored their RPE. After many tests with the same athlete, I could predict what their pace (or power) at lactate threshold would be based on RPE. One triathlete on his running tests would consistently reach his lactate threshold at a RPE of 16 (using the 6 to 20 scale). The blood data backed this up. We never went solely on RPE, but it was a tool athletes could use in the field if HRMs or powermeters failed.
To me, RPE provides another piece of data. While my GPS or HRM will get me some numbers, I also want to gather information on how I feel. If the data seems to be out of what I normally experience, then I will assess myself to see if I can determine a cause.
Another advantage of RPE is that technology sometimes fails you and RPE gives you an idea of how hard you are working. It can also free you from that technology which can be liberating. RPE is also great for that person who is not into tech but that wants to track the workouts.
So if you are into uploading your data, in the comments section add RPE for that session. Do this for a time period to see how well it tracks.