Reps in Reserve (RIR) is a training concept that refers to how many repetitions you could still perform at the end of a set before reaching failure. Using RIR as a guide helps manage training intensity and fatigue, which is crucial for maintaining long-term consistency in strength and muscle growth.
When you leave some reps in reserve—typically one to three reps—you avoid training to absolute failure every set. This approach allows you to train hard enough to stimulate muscle growth and strength gains while reducing excessive fatigue that can impair recovery and increase injury risk. For example, training at an RPE (Rate of Perceived Exertion) of 8 to 9, which corresponds to leaving 1-2 reps in reserve, is often recommended for compound lifts. This balance helps you perform more total reps over time and maintain quality in your workouts without burning out[1][2].
Training to failure can cause greater fatigue and longer recovery times, which may limit how often you can train. Studies show that training just short of failure produces similar muscle adaptations but with less accumulated fatigue, allowing for more frequent and consistent training sessions. This is especially important for long-term progress, as consistent training with manageable fatigue leads to better overall gains and reduces injury risk[1].
Using RIR also helps accommodate daily fluctuations in energy and recovery. On days when you feel less recovered or more fatigued, adjusting your training intensity by increasing your reps in reserve can prevent overtraining and support steady progress. Conversely, on good days, pushing closer to failure can maximize stimulus without compromising recovery[2].
Beginners often struggle to accurately estimate their reps in reserve, sometimes thinking they are closer to failure than they really are. Practicing to failure occasionally helps improve this skill, enabling better self-regulation of effort and more effective training over time[4].
In summary, incorporating reps in reserve into your training strategy is a practical way to balance effort and recovery. It supports long-term consistency by managing fatigue, allowing for frequent training sessions, and reducing injury risk, all while still promoting strength and muscle growth.
Sources
https://rippedbody.com/rpe/
https://dr-muscle.com/maximizing-muscle-growth-the-role-of-rpe-in-hypertrophy/
https://fitforgolf.blog/strength-training-for-golf-guide/
