Glossary · Fitness
RIR (Reps in Reserve)
RIR indicates how many clean reps could still have been performed at the end of a set.
Why it matters
RIR is a subjective estimate of how close a set came to the current repetition limit. It can help guide effort, but it is not an objective measurement.
Many productive strength and hypertrophy sets end before complete muscular failure. How close a set should go depends on the goal, exercise, technique and accumulated fatigue.
RIR is self-reported. Accuracy can improve with experience but still varies by person, exercise and set.
Training to failure is a tool, not a requirement. One RIR value does not determine the effectiveness or safety of an entire program.