Reps in Reserve, or RIR, is a simple way to measure how hard you are pushing yourself during a workout. When you do light weight training, it means you are using weights that are not super heavy, so you can do more reps before getting tired. RIR tells you how many more reps you could have done if you kept going. For example, if you stop at 10 reps and feel like you could have done 2 more, your RIR is 2. This helps you stay in control and not push too hard or too easy.
Using RIR in light weight training is useful because it helps you find the right balance. If you always go to failure, meaning you do as many reps as possible until you can’t do another, you might get tired too fast or feel sore for days. But if you always stop too early, you might not get the full benefit from your workout. By aiming for a certain RIR, like 1 or 2, you can make sure you are working hard enough to see results without overdoing it.
RIR also helps you listen to your body. Some days you feel strong and can push a bit more. Other days you feel tired and need to back off. If you use RIR, you can adjust your effort based on how you feel. This makes your workouts more flexible and helps you stay consistent over time.
Another benefit of RIR in light weight training is that it can help you avoid injury. When you leave a few reps in reserve, you are less likely to use bad form or push your muscles too far. This is especially important when you are doing higher reps with lighter weights, because it’s easy to lose focus and let your technique slip.
RIR also makes it easier to track your progress. If you keep the same weight and reps but notice your RIR is getting lower, it means you are getting stronger. If your RIR stays the same, you know you are working at the right level. This way, you can see how your body is responding and make changes as needed.
Sources
https://runlovers.it/en/2025/strength-for-runners-heavy-weights/
https://rippedbody.com/rpe/
https://www.womenshealthmag.com/uk/fitness/strength-training/a69105961/two-30-minute-workouts-build-strength-study/
https://www.mensjournal.com/health-fitness/what-is-escalating-density-training
https://www.youtube.com/watch?v=2S4LwKoKMY0&vl=te
