RPE: An alternative to heart rate.

We use distance to determine how much you should run, and days per week to tell us how frequent we should run. But what do you use to determine at what intensity your runs should be? How do you rate how hard a training run was?

Heart rate is the popular choice, and is widely used partly due to the advancement in running watch technology. However, if you have found heart rate frustrating for whatever reason, maybe consider using RPE.

The science behind RPE and fatigue:

Training at the right intensity is important in developing the right type of fitness, explained in this blog. Furthermore, fatigue during runs is an important factor when considering what a run is aiming to do. For example, you don’t want to fatigue early during a long run, while you don’t want to slack during speed work or stamina training.

Looking at fatigue, scientists suggest that the brain and the nervous system are major role players in fatigue during endurance events.  In fact, research suggests the central nervous system is the main controller of feeling fatigued during activities like running.

Consider this example: During a run your brain might notice that your body is starting to overheat, or you are running low on energy, or you are dehydrating. So to protect you from getting into trouble, it will “motivate” you to slow down to an intensity where these imbalances do not reach dangerous levels.

This “motivation” is the fatigue you experience, at least in these scenarios. Thus, you slowing down or stopping is a protective mechanism to prevent your physiological systems to cause trouble.

Furthermore, factors like lack of quality sleep or high stress levels (two attributes that directly affects the nervous system) affects your susceptibility to fatigue, that can make a run feel more intense and even increase your risk of injury.

Even your mental state has an impact on feeling fatigue or energised during a run. Remember that boost you get when running past a supportive crowd?

So when you consider these examples, how intense your run is on any given day (and the resulting training adaptation) is influenced by a complex cocktail of factors. Does running at a predetermined heart rate take these things into account?

RPE explained:

Enter rate of perceived exertion, or RPE. This is a subjective self-assessment of how difficult you are experiencing a run or workout, that you quantify into a number. This number summarizes your training intensity, all things considered.

 It’s very easy: You simply rate how hard the run is or was, by giving it a score out of 10.

10 being super hard (past your maximum, which is a 9) and one is walking to the fridge from the couch.

This might seem too simplistic, too subjective or too untrustworthy. But RPE has been researched quite extensively, and have been found to be an effective way to track intensity in aerobic exercise. The reason for this is that RPE is telling you YOUR experience – both mentally and physically, and is a conscious look into your subconscious effort.

By attributing it to a number/rating, it eliminates overthinking and helps you make good training decisions to train smarter and avoid injuries.

This is great, because you can self-assess and modify your pace of a run accordingly. “Rating” the intensity gives you a big picture view of your level of effort.

To demonstrate this, consider the above example of the influence that lack of sleep on risk of injury. On days that you are sleep deprived, heart rate and running pace may give a false sense of running effort. Here, your perception of effort will be your best guide to protect you from pushing to a level your body is not up to on that day. Or maybe you need to keep your intensity low for a long run? Train at 3/10 intensity and stay there. Even if your heart rate is not staying in the zone your watch is telling you to stay.

Heart rate has its place:

Don’t get me wrong, heart rate definitely has its place. Some people respond well to heart rate based training. If that is you, keep at it. I use RPE to communicate the desired intensity to the runners I coach and to monitor their training load (especially in managing injuries). I use heart rate to monitor fitness progress or identify anomalies.

RPE has science’s backing, is used in a variety of sporting codes on a professional level, and it costs nothing to use. Apps like Strava have even built it into their user interfaces. (at the time of writing this, they have an adjustable sliding bar when you edit run).

Practice this way of rating your running intensity, during and after runs. You might get more value out of your training, learn more about your fitness and run smarter every week.

If you would rather outsource the thinking and planning, and just do the running, have a look at the online running coach option by clicking here.

Some research on RPE:

Herman, L & Foster, Carl & Maher, Margaret & Mikat, RP & Porcari, JP. (2006). Validity and reliability of the session RPE method for monitoring exercise training intensity. South African Sports Medicine Association. 18. 10.17159/2078-516X/2006/v18i1a247.

Johnson EC, Pryor RR, Casa DJ, et al. Precision, Accuracy, and Performance Outcomes of Perceived Exertion vs. Heart Rate Guided Run-training. J Strength Cond Res. 2017;31(3):630-637. doi:10.1519/JSC.0000000000001541