Without a training partner, a coach, or repeated 1-rep-max testing, working out how heavy to lift at home is mostly guesswork for a lot of people. Rate of Perceived Exertion (RPE) and its close relative, Reps in Reserve (RIR), give home lifters a structured way to pick a working weight based on how a set actually feels, rather than a fixed percentage of a maximum that may be out of date or was never properly tested in the first place.
What RPE and RIR mean
RPE scales ask a lifter to rate how hard a set felt, typically on a 1-10 or 6-20 scale depending on the version used. RIR is a more concrete variant built specifically for resistance training: it asks how many more good-form reps could have been completed at the end of a set. An RIR of 2 means the set was stopped with roughly two reps left in the tank; an RIR of 0 means the set was taken to failure.
A pilot study comparing RIR-based prescription against traditional percentage-of-1RM prescription in a cardiac rehabilitation setting found the two approaches produced broadly comparable training outcomes, suggesting RIR is a workable substitute for percentage-based programming when a current, accurate 1RM is not available or not appropriate to test (PMC, 2024). Separately, research on proximity-to-failure training has examined how perceptual responses shift as sets get closer to muscular failure, underlining that perceived effort tracks fairly consistently with objective measures of fatigue as a set progresses (PMC, 2025).
Why this suits home training specifically
Commercial gyms and coached programmes often rely on percentage-of-1RM prescriptions, which assume a recently tested, accurate maximum. At home, testing a true 1RM safely without a spotter is often not sensible, and body weight, fatigue, sleep and stress fluctuate day to day in ways a fixed percentage does not account for. RIR-based training auto-regulates: on a good day, hitting RIR 2 might mean a heavier load than last week; on a rough day, the same RIR target naturally caps the load lower, without needing to know why in the moment.
Applying it practically
- Most working sets for hypertrophy or general strength: RIR 1-3 (stopping 1-3 reps short of failure) is a reasonable default for most lifters most of the time, per the pattern used in the RIR literature above.
- Occasional sets to RIR 0: useful for testing progress, but not something to do on every set of every session — the cumulative fatigue cost is high relative to the marginal training benefit.
- Track it like you would track weight or reps. Write down the RIR you were aiming for and what you actually hit. If sets are consistently landing well below the target RIR, the load is too light; if failure keeps arriving before the target rep count, it is too heavy.
- Calibration takes a few weeks. New lifters especially tend to underestimate how many reps they have left. Comparing your own RIR estimate against how the next set actually goes helps sharpen the judgement over time.
A worked example
Say a home lifter is doing dumbbell rows and the programme calls for a set at RIR 2. They select a weight and complete 10 reps, and at rep 10 the bar speed has slowed noticeably but they are confident they could grind out two more with good form before failure — that is RIR 2, and the set is stopped there. The following week, the same weight feels easier: 10 reps come up at what feels like RIR 4, meaning the load is now too light relative to the target, and it should increase for the next session. This is the auto-regulation mechanism working as intended — the target RIR stays fixed, and the load moves to hit it, rather than the load staying fixed regardless of how the day’s session actually feels. Over several weeks, tracking both the load and the achieved RIR next to each other reveals a genuine trend that a rep count alone would not show, since 10 reps at RIR 0 and 10 reps at RIR 4 represent very different levels of actual effort despite the identical rep count.
A realistic limitation
RPE and RIR are self-reported and depend on honest, practised self-assessment — they are a tool for autoregulation, not a precision instrument, and they take longer to calibrate than simply following a percentage chart. For home training without access to testing equipment or a coach watching bar speed, they remain one of the more practical ways to keep training load appropriately hard without constant maxing out.
Sources
- Rate of Perceived Exertion Based on Repetitions in Reserve Versus Percentage of One-Repetition Maximum for Resistance Training Prescription in Cardiac Rehabilitation: A Pilot Study. PMC, National Library of Medicine, 2024.
- The Effect of Proximity-to-Failure on Perceptual Responses to Resistance Training. PMC, National Library of Medicine, 2025.