Reps in Reserve (RIR)

Reps-in-Reserve (RIR) is a training strategy intended to approximate effort while performing fewer reps than sets to failure. The number of reps-in-reserve is an exerciser's estimate of how many more reps they could have performed before reaching failure.

• For example, if an exerciser performed 8 repetitions but feels they could have performed 2 more reps before failing, then the intensity is 2 reps-reps-reserve, and they are presumably using a 10-repetition maximum load (10-RM load). Common strategies include 1-2 reps-in-reserve, 3 reps-in-reserve, and half-reps/set. Note, "feeling half-reps" is likely unreliable and assumes that the exerciser has some experience with the exercise and the load and can estimate the total number of reps they would perform for a set. RIR can be used in conjunction with a 10-point Rate of Perceived Exertion (RPE) scale. For example, an RPE of 8/10 corresponds to 2 RIR ("2 reps left in the tank").

Opposite Strategy: Sets-to-Failure (reps-to-failure/set)

For more on Reps in Reserve:

• Course: Acute Variables: Performing Sets to Failure
• Article: Should You Perform Sets to Failure?

Evidence-based Summary Statement on Sets to Failure:

Based on a systematic review of all available peer-reviewed and published research, the Brookbush Institute recommends reps-to-failure/set for the optimal improvement of hypertrophy, strength endurance, and/or max strength. However, reps-in-reserve/set is recommended for the improvement of power outcomes and athletes performing high-frequency training (with goals of sports performance, hypertrophy, strength, or power). Note that performing 1-2 reps-reserve/set and 1 additional set/exercise will result in the maintenance of rep velocity and reps/set during a session, reduce post-exercise decreases in performance and recovery, and maintain volume and the majority of the improvements that would result from reps-to-failure/set training. It is also important to note that for most goals, reps-to-failure/set is not the most influential variable. For example, 1 set of reps-to-failure/set is likely to result in less improvement for hypertrophy than 3 sets of reps-in-reserve/set (e.g., volume is more influential). Similarly, load and concentric velocity are more influential for strength, and explosive eccentric and concentric tempos are more influential for power.

• Reps-to-failure/set recommended for:
  • Hypertrophy
  • Strength Endurance
  • Max Strength
• 1-2 Reps-in-reserve/set and an additional set/exercise is recommended for:
  • Power
  • Athletes performing high-frequency training (with hypertrophy, strength, or power goals).
• Acute variables that are likely more influential than sets to failure:
  • Volume: 1 set-to-failure is less effective than 3 sets-not-to-failure.
  • Load: Load is more influential than reps-to-failure/set for strength goals.
  • Velocity/force (repetition tempo): Concentric velocity and force production are likely to have a larger influence on strength and power (and potentially hypertrophy) than reps-to-failure.

Frequently Asked Questions about Reps-in-Reserve

What are the benefits of RIR when compared to sets-to-failure?

• As mentioned above, RIR likely results in significantly less muscle damage, post-exercise decreases in performance and fatigue, and long recovery times. This is beneficial for athletes with high-volume/high-frequency training and game schedules. Further, RIR aids in maintaining concentric contraction velocity and force production during a session, which may be beneficial for increasing strength and power.

How does RIR relate to the Rate of Perceived Exertion (RPE) scale?

• Both RIR and an RPE scale are methods of rating perceived exertion or intensity. As mentioned above, RIR can be used in conjunction with a 10-point RPE scale. For example, an RPE of 8/10 may approximately correspond to 2 RIR ("2 reps left in the tank").

Is training with RIR as effective as training to failure for muscle growth?

• Research suggests that sets-to-failure is likely more effective than RIR for hypertrophy. However, it should be noted that muscle growth still occurs with RIR strategies, and there are likely other acute variables that are more influential (e.g., Sets Per Muscle Group , Load , Frequency and Recovery Between Sessions , etc.)

How accurate are individuals at estimating their RIR?

• A research study by Emanuel et al. (2022) (1) suggests that the accuracy of an exerciser's estimates increases with fewer reps-in-reserve. That is, an exerciser's estimate of 1 RIR may have near 90% accuracy, but estimates start to become fairly inaccurate (less than 50% accuracy) when estimating more than 3 RIR.

How can I improve my ability to gauge RIR accurately?

• Estimates likely improve significantly with practice, and RIR can also be determined by routinely assessing the number of reps that can be performed to failure.

How does RIR help in preventing overtraining and injuries?

• Research demonstrates that when compared to sets-to-failure, RIR results in significantly smaller increases in serum concentrations of creatine kinase (a marker of muscle damage), shorter recovery times, and a smaller decrease in post-exercise performance (e.g., strength, endurance, power). These findings likely imply that unless the frequency of exercise was very high (more than 4 days/week), RIR is less likely to result in an accumulation of muscle damage that may be associated with injury and over-training.