Reps in Reserve (RIR) is a method used in strength and functional fitness training to gauge how many repetitions you could still perform before reaching muscle failure. It helps athletes and fitness enthusiasts control training intensity without always pushing to complete exhaustion. In functional fitness, which emphasizes practical strength and movement quality for daily activities, RIR can be a useful tool to balance effort and recovery.
Using RIR allows you to train hard enough to stimulate strength and endurance gains while avoiding excessive fatigue that might impair technique or increase injury risk. For example, stopping a set when you feel you have 1-3 reps left in reserve can maintain good form and reduce the chance of overtraining. This approach aligns well with functional fitness goals, where control, stability, and full range of motion are prioritized over simply lifting maximal loads or training to failure[4].
Moreover, training with RIR can improve your ability to estimate effort and manage fatigue, which is important in functional fitness routines that often combine strength with cardiovascular and mobility work. Research shows that pushing to failure can increase muscle growth slightly more, but training with some reps in reserve still produces significant strength and endurance improvements while allowing faster recovery[3].
In practical terms, RIR helps you avoid the pitfalls of training to failure too often, such as poor movement quality or burnout, which are counterproductive in functional fitness where consistent performance and injury prevention matter. It also supports a sustainable training rhythm, enabling you to perform multiple workouts per week with good intensity and volume without excessive strain.
In summary, Reps in Reserve is a valuable concept in functional fitness because it helps balance intensity and recovery, supports better movement quality, and aligns with the goal of building practical, usable strength rather than just maximal muscle size or power.
Sources
https://www.jefit.com/wp/jefit-news-product-updates/exercise-and-strength-training-benefits-boost-health-with-jefit/
https://www.verrotraining.com/blog/why-you-can-leg-press-more-than-you-squat-and-what-that-tells-us-about-training
https://www.womenshealthmag.com/uk/fitness/strength-training/a69105961/two-30-minute-workouts-build-strength-study/
https://the55fitness.com/functional-training/functional-fitness-vs-crossfit/
https://www.tierthreetactical.com/5-best-strength-and-conditioning-programs-that-actually-work/
