Reps in Reserve (RIR) and training to failure are two different approaches used in resistance training to manage effort and fatigue. RIR refers to how many repetitions you could still perform before reaching failure. For example, if you stop a set at eight reps but could have done ten, you have two reps in reserve. Training to failure means performing repetitions until you cannot complete another rep with good form, pushing your muscles to their absolute limit.
Training to failure has been popularized by bodybuilders like Dorian Yates, who believed that pushing every set to the limit was essential for maximum muscle growth. He argued that most people do not truly know their limits until they reach failure and that leaving reps in the tank is less effective. However, this approach can lead to greater fatigue and longer recovery times, which might reduce training frequency and increase injury risk.
On the other hand, RIR-based training allows you to stop short of failure, leaving some reps in reserve. Research shows that this method can still produce significant muscle gains while managing fatigue better. By not always training to failure, you can maintain higher training volumes over time and reduce the risk of overtraining. For example, leaving 1 to 3 reps in reserve on compound lifts and only occasionally training isolation exercises to failure can optimize progress and recovery.
Using RIR also helps lifters gauge their effort more accurately. Studies indicate that people become better at estimating how many reps they have left as they gain experience and fatigue, making RIR a practical tool for safe and effective training. This approach supports consistent performance and reduces burnout, especially for novice and intermediate trainees.
In summary, training to failure pushes muscles to their absolute limit but can increase fatigue and recovery demands. RIR training balances effort and recovery by stopping before failure, allowing for more frequent and sustainable workouts without sacrificing muscle growth.
Sources
https://www.menshealth.com/uk/building-muscle/a69216657/dorian-yates-reps-in-reserve/
https://rippedbody.com/rpe/
https://www.empower.physio/blog-all/rpe-vs-rir-1
https://www.minimumviablepump.com/guides/rir
