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Repetitions in reserve [RIR], can be defined as how many repetitions from failure you feel you are after completing a set. This is a form of relative intensity which depicts the relationship between what you are capable of, versus what you actually did.
An example would be if you did 8 repetitions with a load that is a 10 rep max; you would say you were 2 repetitions from failure or had 2 repetitions in reserve (RIR). This can be a useful tool to prescribe, monitor, or express effort.
It’s important to remember that this can be a moving target. Due to fatigue accumulating from workout to workout what may be 3-4 reps in reserve one week might actually be closer to failure the next week. Or even within a workout you might expect something that felt like 3 RIR on your first set to feel harder and move closer to 0 RIR after repeated sets.
Why do we use RIR?
If used correctly RIR can be an appropriate guide to gauge effort and modulate fatigue as a programming variable. In the simplest terms, it gives us a way to walk the line between working hard enough to elicit an adaptation and working so hard that we prematurely arrive at a point where we can no longer overload our training in the subsequent week or weeks.
Intuitively, it makes sense that it’s probably a good idea to work within a certain proximity of failure to know we are giving good effort and likely receiving an effective stimulus to drive adaptation. For instance, if I only do 3 repetitions with a 12 rep max weight then that was a low effort set and likely not an effective stimulus for adaptation. Conversely, if we work too close to failure too often we may get so great of a stimulus that muscle damage and/or fatigue could impede our performance on later sets within a workout or negatively impact the quality of future workouts.
By staying just a few reps shy of failure we can ensure that we can accumulate a good volume of productive repetitions over multiple effective sets and likely preserve our capacity to have another good training session within the upcoming days for that muscle group. Within most commonly used rep ranges it’s generally accepted that most of our training would occur in the 1-4 RIR range. It’s also assumed that sets that are >5 RIR are likely not very effective for creating an adaptive stimulus and that sets approaching 0-1 RIR create a good stimulus but also generate a lot of fatigue.
Perceiving Your Effort
Most people can easily tell when they should terminate a set when they get a sense of overwhelming fear that they might get crushed by a weight that’s starting to feel a bit too heavy. Think of the voice in your head, as you set up for a heavy bench set, telling you “A spotter would be a good idea right now.”
However, when you ask people to actively think about training with relative intensity they tend to over analyze the concept of RIR and lose all common sense. Although RIR is a very real quantitative measure, our use of RIR is more of a subjective measure of HOW YOU FEEL. For this reason I think it’s best to prescribe a range. I like to use a chart like this:
A Brief Primer on Gauging RIR
3 RIR = (starts getting just a little hard) Our first MOST important landmark to get familiar with. Once you get a feel for 3RIR and 0RIR the rest becomes pretty simple. Generally, when you start pumping out your initial reps in a set each rep is clean, smooth, and relatively fast and consistent in speed. Eventually you may hit a rep that is a little slower and seemingly heavier than the reps before it. This is a good indicator that you likely only have a few reps left in the tank and you’re at or near 3RIR.
2 RIR = (harder but not worried about failing) You could imagine that if you had a spotter and he/she saw the repetition prior slow down he would start to get happy hands because this repetition is definitely a lot more noticeably slower than the one prior.
1 RIR = (oh shit) Although we may not have hit a sticking point in our lift things are getting really slow here. If form hasn’t broken yet, it’s coming soon. If you didn’t have a spot you’d be thinking to yourself… I need to rack this before I hurt myself.
0 RIR = (FUCK FUCK FUCK) Our second most important landmark, AKA “the grinder“. It’s clear that it’s going to take everything you have to finish the rep. This rep is painfully slow and concerning to watch. We honestly don’t even want to hit this on big compound movements where our health and safety would be at risk. However, this is something that can be used on the final week before a de-load with our less complex, isolation movements, machines, or things that are relatively less risky.
Technical breakdown = Even if you can get more reps out with bad form… we call breakdowns in technique 0RIR. Rack it immediately.
Progressing with RIR
Relationship between RIR and percentages:
If you take the time to look at a chart that displays repetition maxes for given percentage of 1RM you can start to pick out trends between different rep maxes. For instance in the NSCA Essentials of Strength and Conditioning book the difference between a 10RM, 9RM, or 8RM is just 2-3 % in load (75%, 77%, and 80% respectively). Although things don’t always work in real life as perfect as they do in theory, these numbers give us a way to reasonably estimate how much an increase in load should impact RIR.
For example if we know that a given load for a certain number of reps is 3 RIR but we want to hit 2RIR, then a 2-3% increase in load would likely land us there. If something feels to be 4 RIR and the target is 2 RIR, then a 4-6% increase in load should bring you to 2 RIR.
If your programming called for 3 RIR in week 1, 2 RIR in week 2, and 1 RIR in week 3, then the assumption is that from week to week an individual could increase load by 2-3%, granted that recovery and fatigue is well managed over that time.
Relationship between RIR and repeated sets:
Earlier we discussed the concept of accumulating fatigue over repeated sets. For instance if you do a set and it feels like it’s 3 RIR and we keep the number of reps the same with adequate and consistent rest breaks between sets, each subsequent set should increase in difficulty and move toward lower RIRs. Work capacity can vary between individuals and training status so it’s important to learn about how much your RIR can change between sets. If you know that under normal circumstances every set will bring you 1 rep closer to failure you can use this to your advantage to predict how many sets you can do with a load or have an idea whether or not you can expect to hit or surpass your prescribed work intensity for the day.
An illustration of this concept in practice may help drive home the point. Let’s say your training program says to hit a set of 10 for 3RIR and repeat for sets of 10 until 2 RIR. Then drop 10% and repeat sets to 2 RIR again.This is how that example may look:
Assuming that 300lbs for 10 reps is 3 RIR:
Set 1 300 lbs x 10 reps @ 3 RIR
Set 2 300 lbs x 10 reps @ 2 RIR
Drop 10% load
Set 3 270 lbs x 10 reps @ 4 RIR
Set 4 270 lbs x 10 reps @ 3 RIR
Set 5 270 lbs x 10 reps @ 2 RIR
Fatigue… A Moving Target
Remember how I said relative intensity is a moving target?
Well, the decisions we make within training as well as factors outside of training may impact ability to perform well in the gym. We program and de-load clients in an effort to preserve readiness and progressively accumulate fatigue as weeks move on. The goal is to prevent too much fatigue from hitting too early so that we can get the most out of an entire training block.
Taking sets to failure, beating yourself into the ground, overreaching/over-training, under recovering, life stress, lack of sleep, and a variety factors may cause you to accumulate fatigue faster than you should. This doesn’t mean you’re not getting stronger but fatigue can can often mask your ability to express your current level of fitness.
The Birth of a “Buzzword”
It’s not uncommon for the evidence based fitness community to latch on to words and phrases like IIFYM, DUP, Carb Backloading, etc. Relative intensity expressed as RIR may just be that next popular phrase you see in 98% of Instagram fitness post captions and for good reason. While it won’t necessarily make or break the program, it is an important concept to understand and apply within your own training as well as the training of your clientele. If at the very least, it gets people to consider a form of training outside of taking every set to and past failure on a daily basis, I’ll call that a win.