RPE and reps in reserve: how hard should you train?
One of the most common questions in the gym is how heavy to go. Percentages of a one-rep max are one answer, but they ignore how you feel on the day. Rating how hard a set was, using RPE or reps in reserve, is a simple way to choose the right load every session.
What is RPE?
RPE stands for rating of perceived exertion: a score for how hard something felt. In lifting, the most widely used version is a 1 to 10 scale based on how many more repetitions you could have done at the end of a set.
What does reps in reserve mean?
Reps in reserve (RIR) is the number of repetitions you had left before you couldn't do another with good technique. Researchers developed a resistance-training RPE scale built on this idea: an RPE of 10 means no reps left, 9 means one left, 8 means two left, and so on (Zourdos et al., Journal of Strength and Conditioning Research, 2016).
How do I use it to choose a weight?
Your program gives a target, for example three sets of eight at RPE 7 to 8. You pick a weight you think you could lift for ten or eleven reps, do eight, and judge how many were left. If you had four or more left, add weight next set; if you had none, reduce it. Over a few sessions you'll find the right load.
How hard should most sets be?
For most people, most of the time, finishing sets with one to three reps in reserve (RPE 7 to 9) is a good balance: hard enough to drive strength and muscle gains, without the fatigue of going to failure. A review of this approach describes using lower RPEs for power and technique work and higher RPEs for strength and muscle building (Helms et al., Strength and Conditioning Journal, 2016).
Do I need to train to failure?
No. Training to failure isn't required for strength or muscle growth, and doing it often adds fatigue and soreness that can reduce the quality of the rest of your week. It also makes technique break down, which is when tweaks tend to happen. Occasional sets to failure on safe exercises, such as machines or isolation work, are fine.
Why is this better than percentages?
Your strength varies from day to day with sleep, stress, food and fatigue. A fixed percentage may be too heavy on a bad day and too light on a good one. Rating effort adjusts the load to how you actually are that day, which helps you train consistently and avoid overreaching.
How accurate are people at judging reps in reserve?
Accuracy improves with experience and is better closer to failure and with heavier loads. In the validation study, experienced lifters were more accurate than novices. Beginners tend to underestimate how many reps they have left. Occasionally taking a set close to failure on a safe exercise helps calibrate your judgement.
How should beginners use it?
Keep it simple: aim to finish each set feeling you could have done two or three more good reps. In the first couple of months, technique matters more than effort, so err on the lighter side.
How does RPE work for running and cardio?
The same idea applies with a different scale. Easy running should feel like a 3 to 4 out of 10, where you can hold a conversation. Tempo efforts are around 6 to 7, and hard intervals 8 to 9. Most endurance training should be easy; many recreational runners do their easy runs too hard.
How does this help if I have an injury or pain?
It gives you a way to keep training without overloading a sore area. Working at lower RPEs, with more reps in reserve, lets you maintain strength while irritated tissue settles, then build back up. We often use it in rehab alongside a simple pain guide.
Should I track it?
Noting the weight, reps and RPE for your main lifts takes seconds and shows whether you're progressing. If the same weight feels easier over time, you're getting stronger, even before you add load.
What are common mistakes?
Rating every set a 10 because it felt hard, never going near a hard set so that everything is too easy, and letting technique collapse to squeeze out reps. Count reps in reserve only with good form.
Does RPE change as I get fitter?
The scale stays the same, but the weight that matches each rating goes up. That's the point: you keep working at the right effort while the load rises with your strength.
How can an osteopath help?
When you're training around pain or returning from injury, we help you set the right effort levels and progressions so you keep improving without flaring things up.
See our training hub and our posts on starting strength training and deload weeks. Book an assessment at our Berwick clinic. A 60-minute initial consultation is $149, with no referral needed and HICAPS on-site.
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Book an initial consultation at RISE Sports & Spinal in Berwick. Clear diagnosis, hands-on treatment, and a plan that actually gets you better.
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