RPE's limitation in the measurement of intensity

RPE (rate of perceived exertion) is a widely used way to measure the intensity of physical activity. It’s commonly used in the world of powerlifting and bodybuilding, and as sports training brings over so much knowledge from these worlds of physical preparation, it trickles into athletic development. I think RPE is an awesome way to program for particular exercises. Likewise, I like RIR (reps in reserve) and I’ll often advise people to do exercises at a X/10 effort during coaching, for example, which is similar to the principles of RPE. Why I love RPE is that it is powerfully flexible and when you’re coaching a complex training system, it assists in theoretically balancing stressors.

(basic RPE chart)

Although it would be awesome to predict linear progression in a certain exercise or training quality, it is not the reality of training. I coach non-professional athletes, who all work or study alongside training and at various stages throughout the year, training just can’t be their priority. Work stress can increase. Perhaps there are weddings to attend or social events which are paramount to attend. Perhaps they don’t have access to the finest recovery modalities or have so much time to relax and prepare the ideal food to prepare for the next training session. These factors have an impact on performance. It’ll hinder improvements on a week to week basis. RPE takes into account the reality that loading doesn’t linearly increase over time, and this is fantastic.

Furthermore, if you’re utilising exercises in the gym as a compliment to your sports performance, you’re in a constant balancing act to ensure that these exercises are synergistic in improving the performance of the athlete. The way that my current coaching situation is set up is that the athletes lift after they complete their training sessions. Typically, it’ll be around 6pm-7:20pm on the track, and then 7:20-8:15pm in the gym (assuming the training isn’t extremely metabolically taxing, such as speed endurance work, or the athletes are efficient with their training times). If an athlete were to PB on the track, it’ll be common for us (TSD coaching staff) to advise the athlete to reduce the intensity of the gym. This is just a guessing game, but we’re theorising that although the athlete may be absolutely buzzing and their nervous system is feeling prima, the athlete has already exerted huge outputs on the track and completed a lot of work. We’ve had instances in the past where the athlete may be on cloud 9 after running amazingly well, attempting to max out in the gym, and hurt themselves. There may be a perceived sense of preparedness, but the fatigue accumulated from the track hasn’t hit the athlete yet. This could be another circumstance in which RPE works well - “make your main lift a 6/10 tonight, it’s been a big day on the track”.

(Example of an RPE10 deadlift I did in 2015. Felt intense in the moment, felt intense for days afterwards.)

Where RPE falls apart is when the loading parameter of an exercise is based upon velocity. RPE, in my opinion, is extremely effective when loading is mechanical or metabolic. How much weight is being lifted? How hard are you pushing this set? When exercises are metabolically or mechanically loaded, there is such an immediate sensory experience which is easy to gauge. Furthermore, stress is easier to track when loads are based upon mass or work can be measured by sets and reps. When velocity is introduced into the equation, things become complicated for a few reasons:

• The sensory experience is turbid for the athlete.

• There can be an inverse relationship between maximal effort and output.

• Neurological fatigue is just really hard to understand and measure.

Practically then, the loading of velocity can be utilised when chasing adaptations such as power, RFD, elasticity and speed. Not that I’ve ever seen someone program an exercise such as a pogo hop with a RPE of 6 for example, but exercises such as a pogo, or just sprint and power work in general, become hard to program for without having a reference point such as RPE. This is where the importance of tracking the variable of velocity and understanding athlete response comes into play.

Speed needs to be measured in time. It may be measured in average m/s for a fly-in distance, such as a 40-60m zone; or it may be measured in totality from point A-B, such as a 20m or 60m time. This becomes an important reality for clinical application, as in my relatively short experience in sports, it’s not uncommon for athletes to be given programs by physios or external coaches, particularly in a rehabilitative context, in which they’re asked to run at a particular percentage effort. E.g. programs such as Wk1 10x50m @70%, Wk2 10x50m @75%. What is 70% in this context? Is it perceived exertion? Effort? Of maximal velocity? Of total time? 70% in this context can be likened to an RPE 7. From an understanding of stress and load, it doesn’t really mean anything. It’s common to witness athletes run at a 70% run beyond 90% maximal velocity - as such, although the RPE was at 7, the loading may far exceed that. If the intensity of the exercise is important, which there probably always is, there needs to be an attempt to create a variable which reflects and measures intensity.

(One of our athletes running a 20m fly PB - reported that it felt like shit after the run. There can sensory disconnect between outputs and perceived exertion when it comes to sprinting.)

So how can you overcome this problem? Particularly if you are prescribing running based programs remotely?

• Ask the athlete to hold a stopwatch and time from the same point every time. This may be from the first movement or first footfall. It’s not perfect, but as long as there’s consistency from rep to rep and week to week, you’ll be able to incrementally increase the intensity of the training over time. The athlete needs to be held accountable to an intensity depending upon their stage in a rehabilitative or performance based program.

• Prescribe running distances which promote the velocity you want them to run at. Examples of this may be, that if you didn’t want an athlete to run over 80% velocity, drill them extensively through dribbling and skipping, and then get them to run either extensively (as they will not run fast if they have to run long) or over short distances. I like Derek Hansen’s protocols of his 10x10m - it’s a lot of work completed at sub maximal velocities and could be comfortably scaled to go from 10x10m to 10x15m, 8x20m, 8x25m, 6x30m, etc.

• Prescribe task based constraints which promote the velocity you want them to run at. Wickets, hills, sleds, prowlers, drills, etc. all have a way to promote a particular velocity.

Power and ballistic exercises need to be measured by their outputs, as opposed to their mass. When I max hang clean, it doesn’t feel like an RPE10. There’s an ease to this exercise, similarly with medicine ball throws or jumps, which is required to ensure that the skill is executed efficiently and fluidly. Yet, shortly after completing such highly neuromuscularly demanding exercises, and despite not being short of breath or having a huge muscle pump, my hands are shaking. The next day I wake up and my traps may be sizzled. You don’t really know what you’ve gotten yourself into when training power until you wake up the next morning. This is where the usefulness of a VBT device can assist. Do you want to be training at peak power all the time? How much of that can you handle? Would it be best to select a particular velocity just short or just above peak power, for example, to train at in order to sustainably improve your outputs? Furthermore, how did you respond to the stimulus? Did you flatline for a few days afterwards, for example. I've listened to anecdotes of Ben Johnson requiring close to 3 weeks rest following a 3x60m session due to the immense outputs. What RPE is that? How was it perceived by Ben in the moment?

This is a trap that I have fallen into in the past. That is, because I am not wrecked by a mass squashing me or because I’m metabolically not fatiguing (I’m probably accumulating lactic sets by set, but I’m far from chunder) - I continue to do more and more sets because I feel amazing. Likewise with plyometric options, it’s difficult to understand their stress or their recovery time (particularly if you’re not able to measure ground contact times on repeated plyometrics). My advice would be that when it comes to plyometrics, particularly if you did not grow up doing them, do 50% of what you think you can handle from both an intensity and volume perspective and then stay there for 8 weeks. It’s difficult to measure the impact they’re having on your body and it’s easy to continuously want to intensify through easy to measure variables - such as jumping over higher hurdles (as opposed to measuring GCT).

(Video of mini hurdle hops. Muscularly and metabolically, feels like a walk in the park. They are however, extremely intense despite the low perceived exertion.)

Essentially, you need to choose some variable(s) other than mass in order to have an understanding of stress and exertion when you’re chasing elastic or power adaptations; and you need to steer clear of an RPE type mindset when it comes to your running outputs. There are many variables which could possibly be tracked. Perhaps the variable is velocity, such as in the case of olympic lifts; but it may also be distance for throws or ground contacts for plyometrics. On top of consistently tracking this variable(s), you need to monitor athlete response in some way. I think we all can predict what the response for an RPE9 5x10 Back Squat type session may feel like - you’re going to feel absolutely shredded for a few days afterwards. What can you predict for a 3x60m session? It is hard to know. You need to work with the athlete for a long time, and overtime, you can build programs which more accurately predict the athletes readiness for subsequent sessions, and then this is where the training truly becomes exceptional.

Takeaways from this article:

• RPE reflects intensity for metabolic and mechanical loading

• RPE doesn't reflect intensity when velocity is an important variable

• Measuring CNS/neurological stress is difficult. Monitor athlete response in subsequent days for a better reflection of training intensity than immediate sensory experience felt by the athlete.

(My hands were shaking 10 minutes after this clean. RPE was low, intensity was high. Took days to recover.)

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