Deciding between percentage or rir weight selection

There are two basic ways that we program weight selection in the Workout Builder:

1. Percentage-based weight selection 
2. RIR

Percentage-based weight selection is reserved for main lifts only and is based on a percentage of your estimated 1 rep max (1RM). This will give you specific instructions for how much weight to use on a specific set. The plus side is it’s very intuitive. The downside is that it’s inflexible and does not take into account daily fluctuations in lifting performance. For example, 75% of a 1RM for 8 reps may feel very easy one day and soul-crushing another.

RIR refers to "repetitions in reserve." More simply stated, it’s the number of reps remaining before you’d no longer be able to complete a rep with good form (technical failure). This means going to failure is RIR 0. If you did a set of RIR 1 then you stopped 1 rep shy of failure. RIR 2 means you stopped 2 reps shy of failure and so on. In terms of programming, RIR can guide weight selection. For example, your program lists 3 sets of 8 at RIR 2, which means you would select a weight you could do for 10 reps before failure and do it for 8 reps. When it comes to multiple sets this can be confusing because a weight you could select for your first set of 8 may be an RIR 2 on the first set but it might be an RIR 1 by the last set. So how do you select weights in this situation? There are 2 ways:

1. Select a weight where you reach RIR 2 by the final set. This means it may be a slightly higher RIR for the first few sets
2. Select a weight that is RIR 2 on the first set & then reduce it if you need to on subsequent sets to keep the RIR at 2

There is no right or wrong way to do this. It’s a personal preference. 

It’s also important to note that beginners, intermediates, and women especially tend to underestimate their RIR. Research suggests people may underestimate by as much as 5 reps on average. That is, people marked an RIR of 2 for example, but when they had them train to failure, they got 5 more reps than they estimated. So be sure you are actually pushing yourself hard enough. 

RIR is also very useful because it allows you to be more flexible based on your fluctuations in lifting performance. Whereas percentage-based weight selection is rigid, RIR can be adjusted based on how you feel on individual days. For example, on one day 3 sets of 8 at RIR 2 maybe 200 lbs. but the next week it may be 190 lbs because you had less sleep and don’t feel as strong and aren’t performing as well. RIR gives you the flexibility to auto-regulate.