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Calisthenics Training Variables
When we plan our training, after choosing a set of exercises through the process of exercise selection, the next step is programming specific variables that add more specificity in terms of exercise description.
In terms of the most important variables, there are two qualitative and two quantitative variables that are present and should be controlled in every program.
Load and proximity to failure define the type of adaptations we stimulate, but also to which extent we stimulate them. Volume defines the dosage of that stimulus, and frequency determines the time interval between two independent bouts of that stimulus.
In this article, I want to take a closer look at the proximity to failure parameter and give you some overview as well as practical recommendations on the methods of its quantification and monitoring it.
Failure
Before we get to the proximity to failure variable, we need to understand a concept of failure in resistance training upon which the entire parameter is based.
Failure, also known as muscular failure, momentary muscle failure or task failure, is a point in a set where it is impossible to continue to exert the force or torque required to complete another rep or second at a given load, despite maximum effort. This inability is the result of fatigue, which accumulates over the course of a set.
Why Does Failure Occur Exactly? (For The Curious)
Now, for those who are curious, let's briefly discuss how failure actually occurs, as we currently understand it. As we perform repetitions (or seconds) of a given exercise, fatigue builds up. Due to this buildup, we become unable to recruit enough muscle fibers to "get the job done”. This happens despite maximum effort, to be exact - maximum perceived effort.
The word "perceived" is key. By increasing our level of perceived effort, we create a motor command and recruit a pool of motor units within a muscle region responsible for a task at hand.
You can see this in the visual representation below. Each rectangle symbolizes a single motor unit containing a certain number of muscle fibers:
At the same time, negative perceptions that occur as the exercise set progresses are communicated to our pre-motor and/or motor areas in the brain and also increase this perceived level of effort. This probably happens through corollary discharge (basically, pre-motor or/and motor areas in the brain make a copy of a signal and send it to the somatosensory part of the brain), although it could also happen partially through afferent feedback (muscles send the signal through afferent nerves to the somatosensory part of the brain).
Likely, what happens is that due to these perceptions, at a certain point the level of effort exceeds the point we can tolerate, and therefore we can’t increase the activation of fibers further (despite the fact that we feel like we are putting our full effort at a point of failure). Then, inevitably we won’t be able to produce more torque to complete another rep/second.
The mechanism of improving motor unit recruitment is likely closely related to it. We increase how much effort we can tolerate, and therefore how many motor units we are able to recruit. The more motor units we recruit the more fibers are engaged in contraction and the larger the potential force of that contraction.
Technical Failure
The practical problem with the definition of failure is that we rarely perform each repetition and each second of exercise in the exact same way. And changing the form of exercise during the set is rather a very subtle, linear process than sudden jump.
This won't have much effect on exercises that require little coordination. We could say that in these exercises we reach task failure, which happens because of the actual fatigue buildup.
The more muscles and coordination the exercise requires, the more variability there will be between reps. For example, let's say we're doing handstand push-ups and we want to do the set to failure. As we progress through the set, our back will gradually become more arched, allowing us to use a more mechanically advantageous position.
What is sometimes used is the term "technical failure", which means the point in the set where we are unable to maintain the same technique. I think the easiest practical way to deal with this is to have certain arbitrary standards that come from our goals. And then failure means falling below those standards due to fatigue. The standard could be defined by a range of motion, body position, or momentum generated by other body segments.
Another problem with failure and movements that require a high degree of coordination is that sometimes the set can be completed due to another variable - balance. If we are doing an exercise where balance is an important consideration, then we must remember that reaching failure due to balance is not physiologically the same thing.
The Concept of Proximity To Failure
When the concept of failure is understood, proximity to failure begins to be self-explanatory. Proximity to failure means how far we take a given set and how close we get to the point of reaching failure. We could say that this variable is about the effort we put into the set, which is separate from the load.
During a set, the load can be very low while the effort is very high and vice versa, and we can track the effort by how close we are to failure.
Let's say I select the load and do a set of pull-ups with 20 KG attached to the belt. My max in this set would be 8 reps. After reaching 8 reps I would not be physically able to perform another technically valid rep. However, instead of doing 8 reps, I do 6 reps. Likewise, I finish the set without reaching the point of maximum effort.
There are a couple of methods of judging the proximity to failure, and these methods are either subjective or objective.
RPE and Reps in Reserve
Let's start with the subjective methods, which are the methods that the vast majority of people use, and which are probably the only valid methods in the case of most calisthenics exercises.
The subjective methods are derived from the Borg Scale, which has been used in the medical field since 1970, when it was created by the Swedish physiologist Gunnar Borg. The original scale includes points from 6 to 20 that describe the perceived exertion of a person performing a physical activity. From very very easy to very very hard. Since that time, many versions of the Borg Scale modifications have been developed.
One of them is the 1-10 RPE Scale, which is very often used in the context of resistance training. Let's say we are doing a set of exercises with a certain load. Before the set, we can decide that we want to take our set to RPE 9. Then, when we perform it and feel the level of difficulty equivalent to the planned RPE, we stop the set.
What can be used very effectively is called reps in reserve. Reps in reserve is another model describing the exact same principle. With this, we can decide that we will do our set until reaching the point when we have for example about 1 rep in reserve.
As you can imagine, these are not the perfect tools. First of all, whenever we evaluate things based on how we feel, our evaluation will fluctuate based on our emotional state. So one day we might be more motivated and go over the edge of failure, and another day we might be too far away from failure. This will also be a very individual thing, probably influenced by the psychological characteristics of the person.
It also has to do with experience. People who are not used to any kind of resistance training will not really have a clear idea of what failure is. And so they will be less likely to hit that point accurately. RPE and Reps in Reserve also tend to be less accurate when dealing with lighter loads and lower proximity to failure. That is, they are likely to work best when dealing with heavy and moderate loads and proximity to failure not exceeding 3-4.
Do RPE and Reps in Reserve Differ?
The only difference between RPE and Reps in Reserve models is that RPE could be an independent metric for individual repetitions. If you perform each set at maximum intended velocity, you are putting all your effort into the rep and technically the RPE will be 10 in each rep. Reps in reserve, on the other hand, are strictly the variable of proximity to failure.
Velocity Based Training
Given the potential problems with the subjectivity of the methods above, such as the fact that our effort level can be influenced by things outside the perception of effort and fatigue (such as emotions), there is another method of dealing with proximity to failure in an objective way, which is to measure the velocity of the repetitions (technically the rate of movement). This method is called velocity-based training and it actually has many different applications in resistance training.
The basis of this method is based on the fact that during the resistance training set, our concentric portion of the repetitions slows down in a certain pattern as we approach failure.
If I perform bicep curls with a moderate load and put all my effort into each rep, the first few reps will be very fast, but as the set approaches failure, despite my maximum effort, the reps will slow down until they are very slow. In gym jargon, these last reps would be called "grinders”. This slowing down is obviously due to fatigue. And if there is a consistent pattern that exists in this loss of speed, we could use that to assess the proximity to failure.
In practice, what you need is either a specialized speed-based training device or alternatively an app on your phone. One way to use it is to do a set at a given RPE that you judge subjectively and then look at the velocity loss and judge what the actual proximity to failure was. The second way would be to have something that could communicate to us during a set that we have exceeded a certain velocity that represents a given proximity to failure. The most important rule to remember is that we must always perform the concentric with maximum effort to make it work.
As you can probably imagine, this is not a perfect system and there are limitations to this approach. Velocity loss percentages vary between exercises, individuals, loads, and even set to set. However, we can create an individual, exercise specific velocity profile by performing a set of a given exercise to failure. Then that absolute velocity of concentric with a certain proximity to failure will be a consistent number that we can use.
If I want to stay at 3 reps in reserve, I can just look at the number that represents 3 reps in reserve in terms of absolute velocity and have an app or a device or someone tell us when that velocity is reached. It can also be a tool for measuring progression. We can simply compare the speed of our rep with a given load in the spare couple of weeks or months, and if we move faster, that means we probably got stronger because we can finish the same set with a lower proximity to failure.
Now, the real question that comes up is whether this approach is better than reps in reserve, and most importantly, if it works when applied to calisthenics. So, obviously, if we do it in a way that I mentioned at the end, this approach should be objective. But what it can't account for is technical error and variability between repetitions.
I can certainly see this approach working in the case of streetlifting, with weighted pull-ups and weighted dips. It will also work very well with the compound barbell exercises that we can add to our program as accessories, and these are usually included in the algorithms of the popular velocity based training apps.
However, using it for exercises that are more goal specific may not be the best idea because the technical aspect can add too much variability between reps.
The final potential negative of this method is that it requires more equipment and more time to set up, which reduces its practicality.
PTF Exists Regardless if We Monitor it
It is important to note that proximity to failure is a variable that occurs whether we pay attention to it or not. Some coaches ignore the inclusion of methods of measuring proximity to failure that we have gone through in this lesson.
However, by simply prescribing reps at a given load, whether they like it or not, they are manipulating the variable. If we tell an athlete to perform a set of 8 reps with a given load, and he stops at 8 reps when he could do 10 reps on that set, he is doing a set with a proximity to failure of 2 reps.
PTF - Static Exercises
In calisthenics we perform many static exercises. The methods we have been going through seem to be designed for traditional exercises. We should therefore figure out the way to convert the concepts we talked about to isometric training.
In isometric based exercises, failure can simply be modified to be the point at which we are unable to hold a particular position and the contraction becomes eccentric in nature.
We don't have the ability to objectively judge isometric exercises by speed, since obviously there is no change in speed during the set before we reach the actual point of failure. Therefore, we have to use subjective methods of assessment.
Instead of specifying seconds, we can specify seconds in reserve, and this will imply that we will take a given load to that proximity to failure no matter how many seconds we accumulate.
