Ok, slowly wrapping it up. I had originally intended to make this the last piece but it got way too long so I’m splitting it in two. NEXT TIME (PROMISE) I’ll put up videos demonstrating muscular failure including several of myself training. I’ll also show you what NOT going to failure looks like, those will be videos of others. In any case.
Last time, I finally got to the point in terms of defining actual muscular failure, stating:
Muscular failure occurs when the trainee is unable to perform another repetition despite a maximal effort being given.
With the bolded bit being what’s important. Yes, adding the rider of “maintaining proper form” should be added to that. Bringing up the differences between complex compound exercises and machines, the issue of training status, focus, etc. I won’t repeat that here.
Table of Contents
Your Muscles Don’t Care About Any Other Definition
But truly the above is the only definition of actual physiological muscular task failure that can be accurate. If the lifter simply gives up because it’s uncomfortable, that doesn’t say anything about what the muscle is experiencing.
Because in the sense of what stimulates the target muscle to adapt and grow, what matters is what it experiences physiologically (i.e. in terms of recruitment, tension, etc.). If your low back gives out on squats before your quads got a proper stimulus, the “failure” has no relevance to the quads. If you give up because it hurts too much to keep going, that has no relevance to the quads.
Failure occurs when another repetition cannot be performed despite the trainee giving a maximum effort.
And I’d reiterate from last time that using a slowing of rep speed below a target is not only not a good definition of failure but will actually preclude someone from taking a muscle to physiological task failure.
Bar speed will generally and generally must slow the closer someone gets to task failure. If the bar doesn’t slow, or the set is stopped when it slows, by definition that set cannot be to true physiological failure.
So let me get up my ass a little bit more by looking at why this matters. Yes, I’m repeating myself. I find it’s necessary to get my point across to people.
Why is All of this Important?
Other than “to give me something to write about for 6 weeks”, why is this important? I’ve already sort of gone over this ground but briefly one more time.
In a research sense, the only meaningful way to compare papers is if they are using a consistent. Two studies using two different definitions of failure can’t be meaningfully compared. And there’s already too damn much variability between studies (doesn’t ANYBODY replicate anymore?).
If sets are taken to a standardized definition of muscular failure, then they can be compared. And I’ve already cited a couple of papers in that regard so I won’t do it again here.
But it’s also important in a practical sense. Well several practical senses. One is that if you want to make any sort of attempt to compare different training styles, you need the same consistency of definition. If one person says their system is 16 sets/workout to failure but their definition of failure is not the same as someone who says that they only do 8 sets/workout, you can’t compare the workouts meaningfully.
But there’s a second issue. Now, early on in this series I made the point that I did not intend to argue (or even look at the research) on whether or not training to failure is or is not an optimal way to train in either the short of long-term. That’s a totally different question than “How do you define muscular failure?”
Now I might in the future primarily because someone else recently wrote a piece about such, much of which was crap. But who deleted my criticisms and blocked me for pointing that out. Remember kids: the easiest way to appear right “is to make sure nobody is allowed to point out that you’re wrong.”
However, regardless of anything else, there is a singularly important reason that all trainees should spend at least part of their career training to true muscular failure as defined above.
And that reason, as I commented on last time, is this: until you’ve spent some time training to true failure, happily with a happy sadist like me talking you through the set, you do not have a CLUE where muscular failure lives. Not a clue.
Again, I base this on 25 years watching people in the gym and you can prove me wrong by sending me a video link. But realistically you don’t know what true failure is. And until you’ve trained to that level, I mean really trained far beyond what you think your limits are, you’re most likely deluding yourself.
And this brings me to the next and final issue I want to discuss before I put up a bunch of videos showing you what I’m talking about.
Gauging Exercise Intensity in the Weight Room
Over the decades, strength training has attempted to find ways to monitor training load. This includes within a given workout or in terms of the overall training program. Many of these methods are terribly impractical involving blood work to measure things like CPK, the testosterone/cortisol ratio and many others.
Others such as bar speed have become popular and a slew of apps and devices to measure bar speed during training have been developed. Some of them might even be worth a shit.
Probably one of the most common methods used to set or gauge intensity was as percentage of 1 repetition maximum with endless complicated periodization schemes recommending that a lifter perform some number of sets and reps at some percentage of their maximum. This always had the problem that daily variations in strength would throw the percentages off.
But in recent years, newer methods (well one older but differently applied method and two newer methods) have been developed in an attempt to better allow training to be monitored or regulated. I want to take a look at three of them: RPE, RIR and what I have been (somewhat wrongly calling) RTF.
A good review of this topic, from which much of the below discussion comes from is Methods for Regulating and Monitoring Resistance Training by Eric Helms and co-authors.
Rating of Perceived Exertion (RPE)
RPE is a method of subjectively estimating exercise intensity. In the realm of aerobic activities, it’s been around literally forever. Ok, well maybe a handful of decades. The original scale, called the Borg scale ran from 6 to 20 where 6 was no effort and 20 was maximal.
Fun fact: The 6 to 20 scale was meant to correspond to heart rate by simply adding a zero. So a 6 was a heart rate of 60, essentially resting. 20 was a heart rate of 200, essentially maximum.
Related: How Do I Set Exercise Intensity?
But this was confusing since scales shouldn’t start at 6 and a modified 10 point scale was developed where 0 was no effort and 10 is a maximal effort.
The first research I can find examining RPE in the weight room was published in 2004. However, I don’t recall it really being introduced into practice until Mike Tuscherer wrote his Reactive Training System book in 2008. Certainly he was the first to popularize its use though his method probably had more in common with RIR (discussed below).
So a lifter might be given 6 sets of 3 at an 8 RPE or what have you. Alternately, they might aim to do repeat sets of 3 until the RPE reached a 9 at which point the lifter stopped. This approach has been found to be useful for autoregulating training.
Session RPE can also be tracked, where the lifter gives an overall workout difficulty although this doesn’t seem to be as generally accurate or useful as set RPE. And it’s certainly not as useful as using workout RPE for a steady-state aerobic workout.
A powerlifter who does a handful of low repetition sets near maximum with a long rest might rate each individual set with a very high RPE. But the overall workout might not be nearly as challenging in terms of reported session RPE as a higher volume workout with short rest intervals.
At the same time, RPE does not seem to work as well in the weight room as in other types of activities. Studies have found, for example, that subjects may report less than maximal RPE scores despite going to failure. Logically, a set to true failure should be a 10 RPE.
Mind you, this could be a practice issue. Even for aerobic training, using the RPE scale takes practice. And RPE in the weight room has been shown to improve with practice. For example, trained powerlifters were found to accurately report RPE during training. As well, higher RPE’s are also associated with lower bar speeds and being closer to 1RM. So clearly there is a link here.
But in the big picture, RPE seems to have less utility in the weight room than it does for aerobic activities. Some of this is likely due to the somewhat subjective descriptions of hard, very hard, etc. and the fact that the intensities aren’t really “anchored” to any objective measure.
Arguably, the Borg RPE scoring criterion such as “very hard” or “somewhat hard” are more reliant on anchoring because individuals of different demographics and with different backgrounds (i.e. athletic experience) may have differing perceptions of what constitutes these descriptions.
I talked about this in the last part about how some people can push harder than others and/or tolerate more discomfort. Some of this is probably inherent, some of it is due to training status and can be learned, given differences in biology, there are probably sex based differences. You get the idea.
For this reason, other approaches may have more utility.
Repetitions in Reserve (RIR)
So far as I can tell the RIR scale was developed by Mike Zourdos although something akin to it was first used by Mike Tuscherer in 2008. It’s probably more accurate to say that Tuscherer created it but Zourdos was the first to really study it scientifically. I might have this backwards so spare me the pissy comments. It doesn’t matter in the big picture.,
Quite in fact it the RIR scale incorporates RPE but gives the RPE values a more concrete anchor than subjective effort. Specifically the RPE scores are related to the repetitions in reserve (RIR), defined as the number of repetitions prior to muscular failure occurring. I’ve included the RIR scale below.
The chart should be fairly self-explanatory. If you’re wondering why it doesn’t show values below 7 it’s because RIR becomes pretty inaccurate the further the lifter gets away from true failure. It’s also more accurate for lower repetition sets.
Think about it, on a maximum set of 10 the first 1-6/7 reps all feel pretty much the same. Trying to guess when failure would occur is damn near impossible. For a high rep set the same holds true.
On a set of 30, who could say at rep 15 that they have 15 more? It’s not until the last 4-5 that RIR becomes worth a damn. Of course, it’s not until that point in a set that the set becomes worth a damn so….
One component of RIR is the relationship between bar speed and RPE/RIR. Simply, as a lifter approaches higher RPE scores/lower RIR values, bar speed should slow. And as the lifter approaches a 10 RPE/0 RIR, it should slow pretty enormously.
As Helms et al. state in their paper Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training
Thus, for this RIR-based scale to be seen as a valid measure of assessing intensity, final-repetition velocity should decrease as the score of a given set increases.
Just go look at the typical maximum 1RM by a powerlifter, it’s not moving fast. And if bar speed were to fall any lower, the lift wouldn’t be made. On a true failure repetition, bar speed would fall below what was required to get the weight through the sticking point.
So a true set to failure, RPE of 10, RIR of 0 would have the final completed repetition not only move slowly but significantly more slowly than the preceding repetitions. By corollary, if the bar never slowed, the lifter didn’t really approach (much less hit) failure or an RM load.
Like the RPE scale, RIR has been shown to improve with practice. For example, beginners may mis-estimate their RIR by 3-7 repetitions depending on the exercise while expert lifters may be off by only 0.5 reps.
And this is important for reasons I’ll come back to shortly.
Repetitions to Failure (RTF)
In 2012, Hackett developed a scale to gauge weight room intensity called Estimated Reps to Failure or ERF. I have called this Reps to Failure (probably wrongly) for a very long time and will continue to do that here. For reasons I’m not clear on, it seems to have fallen by the way side in deference to RIR.
Conceptually, RTF was meant to mimic an endurance concept of “estimated time limit”, how much more time an athlete felt that they could keep going at a given pace. Specifically RTF has lifters rate how many reps they have until they think they will reach failure. So early in a set they might estimate 10 reps to failure while later in the set they might estimate 1-2 or even 0 (at failure).
For all practical purposes RIR and RTF might as well be identical although RTF kind of reverses the thought process. RIR conceptualizes the set as “How many reps do I have left?” while RTF conceptualizes it as “How many more could I do?” Same concept, different conceptualization.
Basically an RPE 8/2 Reps in Reserve is equivalent to an RTF of 2. Both indicate that the lifter could perform two more repetitions to failure. And in premise an RIR of 0 would equate to an RTF of 0 which should equate to an RPE of 10.
Very little research on RTF beyond the initial study appears to have been done. Even if found that, like RIR, lifters were less accurate earlier in a series of sets but became perfectly accurate by the 5th set when failure occurred. So like RIR, RTF is likely more accurate near failure. Early reps in a set are all just too much the same.
I would also predict that RTF gets better with practice and basically shares every aspect that I described for RIR including dropping speed as RTF approaches zero. But as I said, the concept seems to have been dropped when RIR came about.
The Problem With All of This
Ok, so we have three scales. RPE is a subjective measure of effort where a 10 is a maximal effort. RIR is more concrete, an estimation of the number of repetitions that the lifter has left in them before failure occurs. RTF just kind of reverses that mentally to the number of repetitions the lifter can do.
And while all three have been shown, to one degree or another, to allow training to be determined, tracked or adjusted, they all share the same fundamental problem in my mind.
And that problem is that all three are anchored on the concept of a maximal effort/sets to failure. Both RPE and RIR take practice to use well (presumably RTF does too) and it’s clear that more well trained athletes are better at using them.
Because the problem with all of them within the context of this series is this:
If you don’t know what a maximal effort/true muscular failure represents, these scales are totally useless.
You can’t possibly accurately estimate that you are 1RIR/1RTF if you don’t know what true failure represents. You can’t know what a 9 RPE is until you’ve been pushed to your limits and experienced a true 10. And even then you probably had more in you that you simply haven’t learned to access.
And as I’ve beaten into the ground, in 25 years of observing people in the weight room, the number I’ve seen even approach a true RPE 10/0RIR/0RTF in almost any movement I can count on maybe a few hands. And despite everyone on the Internet “training harder than any 10 men” well……I’m repeating myself.
To the above I’d add the issue of bar speed since that is a big player here. As a true RPE 10/0 RIR/0 RTF is approached bar speed will (or at least) should slow. This is just a function of the impact of fatigue on movement velocity and all that crap.
By corollary, again, if the bar doesn’t slow, even if the lifter said “they hit failure”, well they didn’t. There’s too strong of a relationship between bar velocity, intensity, nearness to failure and, by extension, RPE/RIR/RTF value.
As I defined in the last part and again earlier in this part, muscular failure is defined as the lifter being unable to complete another full repetition despite providing maximal effort.
What Does Training to Failure Look Like?
So what would a set to true muscular failure look like. Well it would start with relatively quick reps, the ultimate speed being determined by the lift, the distance it has to move, etc. Obviously if the lifter is deliberately controlling bar speed that’s different. But the first handful of reps, up to about 4 RIR/4RTF will be pretty much the same.
Then, in general, bar speed will start to slow. And with each subsequent rep closer to 0 RIR/0RTF the bar will slow more and more. The final repetition, if it is completely should be extremely slow indeed. Again, picture a maximum 1RM by a powerlifter in competition. The 10th repetition of a true 10RM set (i.e. 0 RIR/RTF) should move just as slowly.
Note: there are exceptions. Sometimes lifter go from rep rep rep to failure without any noticeable slowing of bar speed. But in general, the above holds true.
And in the next and what I promise will be the final part of this series, I will show you what a set to true failure looks like. And, as importantly, I will show you what it does NOT look like. Tune in next week.
Read What is Muscular Failure: Failing to Fail.
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