Fast Talk Episode 190 - Is Perceived Exertion the Most Important Metric?

Great Episode…i will start the conversation with this:

I like fantasy stories. Here is a short story for you.

Once upon a time there was a boy… On his daily commute, he would pass a strange restaurant called “Big Shaddow.” Sometimes he would go right to the front door, wait there, and ask the waiters for a single serving of coffee cream. He always got his single serving of condensed milk with a number from 1-10 on the aluminum lid. This went on for years. But one day… the waiters didn’t serve a single serving of coffee cream… There were 2 pills on the tray… one blue and one red, and a message from the restaurant’s big boss: take the blue pill… and you can come back every day and ask for your single serving of coffee cream. Take the red pill…and you’ll get the courage to feel invited to enter…we’ll meet…and you’ll get the big menu, I’ll show you the whole restaurant, including the basement (that’ll be the awkward part). This could be your last chance to meet me… .

The curious boy…he swallowed the red pill…mustered up the courage…and ran in !

… He’s in the basement right now…no it’s not so nice there!

But a gift then is that “RPE” is no longer a simple number ! You will never know or solve the riddle of life…but you can feel it.

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I like explain perceived exertion and listening to your Boddy in terms of if you need to rest, like this.

Be for cell phones and caller ID Bob phones me for the first time ever I answer and go: Hello who is this, Hi its Bob ok hi Bob.

He phones me two days later now he sounds familiar but I don’t know who it is: Hi its Bob here ok ya of course.

Long story short by the fourth time Bob phones me I know exactly how it is but I cant explain to any one how he sounds but there is no doubt in my mind its Bob speaking.

Don’t know if this makes cense English is not my first language.

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Ok, let us put the fantasy beside, it was just meant to be a creative opener to discuss RPE.

2nd Part: Comparing RPE with NRS

What i want to say is that RPE is a metric where you have to look inside yourself. And then you get a value in form of a number. This principle is almost similar to the numeric rating scale to measure pain. Wheter postoperative, in emergency medicine, after c-section or in assements to evaluate chronic pain. It is a daily routine. In contrast to RPE it is the one of the most important metrics to measure pain. The simple NRS (Numeric Rating Scale for Pain) goes from 0-10 (almost similar to RPE) where 0 is zero pain and 10 is the worst pain you could imagine.

“The only reliable way of recording pain intensity is the patient’s self-assessment. For this purpose, the patient must be actively asked about his or her pain perception and indicate the pain intensity on an estimation scale .
The recording of pain intensity in categories of numerical or verbal classifications is inevitable. Without this quantification, efficient pain therapy (dose finding) is impossible.”

So we do not have powermeters or heart rate monitors. Here NRS or the Visual Analog Scale (VAS) is one of the most important tools to evaluate pain. Because "Vegetative pain responses (arterial hypertension , tachycardia, sweating, restlessness) reflect pain intensity unreliably and are therefore of very limited use for assessment.“

„The individual experience of pain is always subjective. The external assessment of pain intensity by a second person shows a considerable discrepancy with the patient’s self-assessment and is therefore considered unreliable and subordinate. In principle, as with other sensory modalities, there is primarily a relationship between the strength of the triggering stimulus and the intensity of the elicited pain sensation. Clinically, however, neither the stimulus strength nor the activity of the nociceptors can be measured, nor can the intensity of the subjective pain sensation or perception of the individual patient be objectively determined, since the pain experience is very much influenced by external and internal factors.“

At least the WHO Definition of pain:

“An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage”

I’m a long distance rider. My stock and trade events are 200km / 125 miles during winter up to 2100km / 1300miles in the summer months.

I’ve been riding them for 11 years now and am mid 50s. You’d think I’d be pretty good at managing the effort after all this time. In 2018 I found I was getting wiped out by the end of my 200km winter events. More specifically I was wiped out in my Dec / Jan events.

This lead to me buying a new GPS which could do HR. I discovered I was hitting 90% at the start of my winter 200s. Purely because I was trying to keep up with riders far faster than me. I was starting it like it was a 1/2 hour race not an event I’d be out there riding for more than 8 hours. Because I could now see my heart rate I backed off. The event went much better I knocked an hour off my previous years time by capping my HR , not working hard early in then slowing down after 5 or 6 hours. By working at an easier rate I was able to sustain it for the full ride.

Anyway moving on to perceived exertion. I would say I’d lost touch with how my perceived exertion related to how hard I was really working. How long could I sustain that level of exertion and after how hard could I work and recover from that harder exertion.

I now ride to heart rate and RPE. The only metric I have showing on my gps screen is my heart rate and usually the map. I now have a good feeling for how my heart rate, its rate of increase or decrease , and my RPE tie together. If I’m heading up a 5 min hill I can pace it well on RPE, I know where my HR will get to be the top. If I’m doing a 20 min hill I again know at what level to pitch it.

Because I have this good sense of the correlation it help in October when I was sick. I had a heavy cold beginning of October. I stayed off bike during symptoms and then got back on it after symptoms had cleared. That’s where I noticed a problem.

I was going up a hill at my usual pacing and my RPE was divorced from my heart rate. My RPE felt like I was riding at VO2 max level but my HR indicated I was at the boundary of Z2/Z3. I felt like I couldn’t go any harder despite my HR saying plenty of head room. The big mismatch between RPE and HR indicated I still wasn’t right. It didn’t feel right. I decided more time taking it easy was necessary with no intensity above Z2.

From this I’d say knowing how your RPE feels in comparison to the metrics your bike computer captures is very useful for picking up when things aren’t right.

I took a whole month before my RPE felt aligned with HR. I’m now able to recommence some of my harder efforts where it feels more sustainable at 90% of my max HR than it did at 75% of max just a few weeks back.

I also find that if RPE no longer matches up with HR on one if my long rides then I need to drink, eat , or stop for a break or all three. Learning the feel has become invaluable in my riding.


I should add that I don’t really have a Borg scale I have a scale something like.

  1. This is about as easy as it gets unless I stop pedalling. Breathing pretty much same as when stationary , legs nice and light on pedals.
  2. My breathing is above 1 but it’s nice slow controlled and could do this all day. Sustained leg pressure on pedals but legs feel good not strained. I’d say this is my all day (and night) endurance pace.
  3. I’m breathing heavier and deeper but I can keep this up for at least a solid hour. Leg muscles feeling the strain but it’s not overwhelming.
  4. I am breathing harder and can feel the heart beating away.chest lightly heaving. I can sustain this for no more than 20 mins. The leg muscles are starting to burn.
  5. I’m really breathing hard , shallower and faster breaths. My chest is heaving, legs burning, heart pumping away. Can’t really go much harder. I can sustain this for no more than 5 mins.

Thank you for the answer, I think you can see that this is an individual process, to get a number from a feeling - and that one can rightly struggle with it. That’s why I think your own design is very good. It’s partly the same with NRS. Therefore, one can also ask in a simplified way- was this easy, moderate or difficult. Special attention should be paid here to the threshold range - here the Talk Test is suitable at the beginning, now you can complete a training in this range by developing a feeling for this threshold LT1, I call this aerobic surfing, slowly and with mindfulness increase the intensity and decrease it again. Similarly around LT2, over & under intervals but with the same gentle intensity increase/decrease as LT1. This way you get a feeling for the subtle physical sensations in these areas and can control the training completely according to this feeling. With a bit more experience one can pace a segment completely by feeling.

For LT1 my talk test is

Recite the alphabet whilst sat relaxing and see how far you can get before taking a breath. Now on the bike recite alphabet and see how far you can get through alphabet before a breath. You should be able to repeat what you did sitting, and maybe fall short a letter or two as you approach LT1.

I’m also playing with DFA1 to see how well that correlates with my own perception.

Which app are you using for DFA a1? I assume real time which means you only have a couple of options. The HRV Logger program has one issue, it only reports the a1 result every 2 minutes and things can change considerably in that time span. The Fatmaxxer can be set for a higher frequency of reporting the results, however it is an Android only app.

I have HRV logger on my iPad. My phone is Android and I’ve loaded Fatmaxxer on to it. The former I’ve had a few months the latter I’ve only just started playing with.

My Polar H10 can broadcast on two Bluetooth channels at same time. In principle I could have both running at same time and showing me their DFA1 value.

For HRV logger I’ve been following the protocol suggested by Marco. That is a gentle ramp , increasing intensity every 6 mins. I do find a warm up necessary to prevent early dips and recovery when measuring DFA1 during relatively low intensity. This concurs with my feeling that it takes 15 mins or so for my body to get up to operating temperature when I go cycling. I’m guessing there physiological changes in those initial minutes as my body adjusts from rest to exercising, which then reach a steady state until you properly up the intensity.

Hi Phil, it is interesting you mention a dip and recovery, I see that same thing happening. I have tried both stepped and a steady gradual ramps and they seem to produce similar results when the ramp rate is similar. I tend to use Runalyze o evaluate the HRV/DFA a1 data after the fact. It does have some very useful tools and ways to look at the data. I have Fatmaxxer but have not used it because I have an Polar H9 and thus only 1 BT channel which is already in use. It is very interesting stuff. Bruce Rogers is one of the gurus of DFA a1 and he mentions a number of things that may impact a1 results such as heat.

I’m wondering if just doing a series of steady state tests would be better. Warm up to reach target HR. Wait till stabilises and then measure for 10 mins. Stop recording. Do the recordings over a period of a few days. Then narrow down where LT1 might be and do more tests around those HR. Of course knowing it to within 5 bpm might be good enough assuming you are not trying to ride at exactly LT1 but stay below it.

You could for instance do a series of steady state at


I do like the rolling 2 min DFA1 you can do in Fatmaxxer.

One thing I have noticed is that my DFA1 0.75 occurs at a much lower HR then when I was at my peak. I am just coming out of my off season. Does show that it moves around depending on your current aerobic fitness.