RIRreps in reserve, and what it's for

RIR stands for reps in reserve. It's the count of reps you could still have completed when you racked the bar. Stop with two in the tank and that set was 2 RIR. Stop because the next rep genuinely was not going to happen and that set was 0 RIR, which is failure.

It maps directly onto RPE: RPE 8 is 2 RIR, RPE 9 is 1 RIR, RPE 10 is 0 RIR. Same information, opposite direction. The difference is what you're asked to produce. RPE asks for a judgement on a scale. RIR asks for a whole number of reps, which is a question with a right answer, and people are measurably better at answering it.

That's why RIR has largely displaced percentages in hypertrophy programming. A percentage tells you what to load. RIR tells you when to stop, which is the decision that actually determines whether a set built anything.

Decide the RIR before the set, not after. Walking up to a set of 10 knowing you're stopping at 2 RIR changes how you pick the weight, how you pace the reps, and whether you argue with yourself at rep 9. Deciding afterwards turns RIR into a description of what happened, which is useful for a log and useless for a prescription.

Progress a block by lowering RIR before you raise sets. Going from 3 RIR to 1 RIR at the same weight and the same set count is a real increase in stimulus that costs you no extra time in the gym and no extra weekly volume to recover from. Adding sets is the more expensive knob and should generally be the second one you reach for.

Keep compounds further from failure than isolations. A squat at 0 RIR costs days. A cable curl at 0 RIR costs minutes. Most sensible programming reflects that asymmetry, and ours does too.

Almost everyone over-states their reserve, and the reason is structural rather than a matter of character: if you've never taken that movement to failure, your sense of where failure sits is a guess built on nothing. Lifters who report 2 RIR frequently have four or five left, and the gap is largest on movements that are uncomfortable rather than genuinely hard, like high-rep leg work.

The fix is calibration rather than willpower. Once, on a machine or a movement that's safe to fail, take a set to true failure and count how many reps came after the point you would normally have stopped. That number is your correction factor and it tends to be stable. Most people only need to do this two or three times across their training life, and it improves every estimate they make afterwards.

The opposite mistake is rarer and worse: treating 0 RIR as the target for every set. Failure on every set is not more training, it's the same training plus fatigue you have to pay off later, usually out of next week's sessions.

Take Dr. Mike Israetel's profile as our code implements it: accumulation opens at 2 RIR and peaks at 0, with deload at 4 or more. Say week one is leg press, 3 sets of 10 at 140 kg, and you stop each set with two clean reps left.

By the peak accumulation week the target is 0 RIR at the same 3 sets of 10. If your reserve was honest in week one, 140 kg no longer reaches failure at 10 reps, so the load has to come up to meet the target. In practice that's somewhere around 155 to 160 kg for most people. The set and rep prescription never changed. The stopping rule pulled the weight up behind it.

Now suppose you arrive on peak week having slept four hours and report rough readiness at the gate. The engine adds a rep back to every target, so 0 RIR becomes 1 RIR, and separately takes one set off, so 3 sets becomes 2. If the muscle is sore as well, a further set comes off. That second cut normally stops at two sets, and on a red readiness day it is allowed to go to one, because at that point the honest prescription is a token of the movement rather than a session. You leave with 2 sets of 10 at 1 RIR instead of 3 at 0, and a session that's honest about the day rather than one you abandon halfway through.

RIR is what Fire Your Coach prescribes. All ten coach profiles express intensity as a RIR ramp across the block rather than as a fixed number, and the ramps genuinely differ. Israetel and Nippard run 2 down to 0. Ryan Humiston opens at 1 and peaks at 0, because intensity is his progression knob rather than volume. Matt Fitzgerald never goes below 2 RIR at any point, because his strength work exists to serve running and anything closer to failure bleeds into the next run.

RIR is also one of the four numeric intensity kinds the database accepts, alongside RPE, %1RM and Zone. A prescription written "2-3 RIR" is parsed into a kind and a range rather than kept as text, which is what lets the readiness engine adjust it rather than just display it.

When you report rough readiness, the adjustment is arithmetic on that stored range: one rep of reserve added back to every exercise that has one, and one set removed. A sore muscle takes a further set off the compounds that train it. That second cut stops at two sets, except on a red readiness day, where the floor drops to one. You can see exactly what changed, because the original prescription is snapshotted alongside the adjusted one and both are kept.

Fire Your Coach reads the intensity your plan asks for, shows it on the set, and adjusts it when your readiness says today is not the day. Nothing to configure.