Cyclists have more training data at their fingertips than ever before, as well as an increasingly complex web of information about how to use that data, but is Perceived Exertion Rating the gadget-free metric you’ve been missing?
Just under 50 years ago, Polar developed the first heart rate monitor for training use, opening up data-driven training to cyclists who want to monitor their level of exertion outside of a lab environment. This was followed nearly a decade later with the release of the first energy meter by SRM.
Power and heart rate are now common among cyclists as a means of using training zones to monitor intensity and target specific physiological adaptations (you can read our guide on training with power versus heart rate).
We are also seeing more innovative technologies that can measure values such as ventilation rate, muscle oxygen saturation and heart rate variability during exercise, and apply complex algorithms to determine training intensity zones in real time.
However, while these technologies are undoubtedly useful, should we also be taking a more basic approach to tracking training intensity?
More specifically, the Perceived Exertion Rating (or RPE) is an underrated training metric that should always be considered no matter how many sensors you have monitoring you. What’s more, you don’t need another gadget to measure RPE and use it as a metric to inform your training.
With that in mind, let’s take a look at RPE, why it’s important, and how to integrate it into your training.
What is EPR?
The RPE is simply an indication of how difficult a session is subjectively. It is often quantified numerically (for example, a 6/10 effort). However, it can also be descriptive (eg very easy, complete, etc.).
How to measure EPR
The traditional approach to measuring RPE is to use something known as the Borg Scale, where exercise intensities are rated on a scale of 6 to 20. 6/20 represents little or no effort, and 20/20 is maximum effort.
The Borg Scale is well validated and widely used in research, but it can also be quite confusing to use. A more practical approach is to rate exercise intensity on a scale of 1 to 10.
This is what we recommend using and we’ve included a table below so you can get an idea of what the different intensities should look like.
Why is RPE useful?
Fundamentally, RPE is arguably the most sensitive and comprehensive indicator of training load; particularly for the so-called internal training load.
Understand internal and external training loads
By internal training load, we mean the load or stress applied to the body, which encompasses the energy systems used, the levels of fatiguing metabolites in the blood, the types of muscle fibers activated, the stress on the central nervous system, how hard the body is working to regulate the temperature and so on.
This is in contrast to external training load, which is simply the amount of actual work you do to press the pedals, measured as the watts you’re producing multiplied by the time you’re pedaling.
Internal and external loads are not necessarily equal.
For example, pedaling at 200 watts when you are rested, well fueled, hydrated and in a cool environment results in a very different internal load than pedaling at 200 watts at the end of a hot, hard race that has depleted your muscle glycogen, damaged it. . muscles, caused dehydration and raised body temperature.
We all know intuitively that the stress on the body is greater in the second scenario because it’s harder to step on the pedals in those conditions. This illustrates well the power of RPE.
Using heart rate to capture internal training load
Internal training load (the stress felt by the body) can also be captured to some extent by measuring heart rate or using other technologies mentioned above.
For example, we often see heart rate increase at the end of a long ride, even when power is held constant. This tends to reflect increased internal load from muscle fatigue, glycogen depletion, dehydration, and increased body temperature.
In this example, at the beginning of the pedal stroke, you will be able to maintain 200 watts at a heart rate of 145 bpm, while at the end of the pedal stroke those same 200 watts require a heart rate of 155 bpm.
The stress on the body is greater in the latter case, and you may want to adjust your power goals accordingly when you start to see signs of heart rate drift (this is also known as cardiac drift).
Come in, RPE
However, heart rate has some drawbacks. Most notably, it only reflects stressors that impact the cardiovascular system and is not as good at capturing other stressors such as neural fatigue and muscle damage, for example.
The same applies to the other measures mentioned above (eg ventilation or muscle oxygen saturation). Until now, all methods for objectively measuring internal load only provide a narrow view of what is happening in the body.
RPE, on the other hand, arguably represents a more holistic picture of how hard you’re working. Crucially, for everyday cyclists, it’s also free, easy to use and can help you better understand your heart rate and power data and any discrepancies you see between the two.
How to use RPE in training
There are two main ways to use RPE in training: monitor your form and readiness to train; and individualize training intensity goals.
Monitoring your form and readiness to train
Using the RPE on a daily basis can help you assess your readiness to train. With this, we look in particular for discrepancies between your RPE and measures of internal/external training load such as power or heart rate.
For example, if you start a session and notice that your RPE seems high in relation to your power output and/or heart rate, this could be a sign that you are not recovered enough for a high-intensity session.
This might mean changing your plan a bit, perhaps taking a recovery day, going for a low-intensity walk, or postponing any high-intensity workouts until later in the week.
Individualizing training intensity targets
As we’ve already covered, many riders now train and race using power and/or heart rate zones.
While they’re great for providing a rough intensity range to work with, they’re rarely perfect and often need a little tweaking to suit your unique physiology.
Paying attention to RPE can be a smart way to do this, and in fact, RPE can often be used as the primary intensity metric when driving high-intensity intervals.
Some common session types are listed below with their associated RPE levels.
Five Tips for Making the Most of RPE
Having learned how the Perceived Effort Rating can be used to improve your training, let’s wrap up with some tips on how to make the most of this valuable metric.
1) Keep a record of your RPE during an entire session
Keeping a record of your RPE can help you monitor that you are allowing enough time to recover and also help you spot possible warning signs of illness.
For example, if you’re consistently seeing RPE ratings of 7 to 9/10 for sessions that should feel more like a 4 to 6/10, then that’s concerning and you might need to take a step back to see if you’re allowing enough recovery, or maybe pushing yourself too hard in training.
Training platforms like TrainingPeaks allow the functionality to quickly record your RPE at the end of each session.
2) Don’t focus exclusively on single metrics
Instead of exclusively using power, heart rate or RPE, try triangulating all the information you have about training intensity to form a better picture of how hard you are working and how fit you are.
For example, if you notice that your heart rate is low relative to your power and your RPE is high, you might conclude that you are a little tired or that you may be seeing early signs of illness.
On the other hand, if your heart rate is low relative to power but your RPE is also low, this could be a positive sign that you are feeling refreshed and your fitness is improving.
Without considering RPE, we would not be able to so easily differentiate between these two very different scenarios.
3) Be reactive to your RPE
That means being willing to adapt your plan day by day based on how you feel. It makes no sense to persist in a high-intensity training session if you’re just not prepared enough to do it well, for example.
4) Hone your RPE skills for competition use
Make a mental note of what the different levels of effort in training feel like and how long you can sustain those efforts. Then keep checking in with yourself during your runs or events to make sure you’re maintaining the effort you know you can maintain.
5) Use RPE to help with power control
When it comes to RPE, you can drill down into the feel of each individual pedal stroke, and this can be a great way to help keep your power in check during training.
After you’ve done a few pedals at your desired power, try to remember what that power feels like and try to emulate that with each subsequent pedal stroke.
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