Minimum Viable Pump

What is RIR? Understanding Reps in Reserve

The science-backed method for quantifying training intensity without always going to failure

Reading time: 6 minutes

Key takeaway: RIR = how many more reps you could have done before failure

What Does RIR Mean?

RIR stands for "Reps in Reserve" — the number of additional reps you could have completed before reaching muscular failure (the point where you physically cannot perform another rep with proper form).

RIR Scale Explained:

  • RIR 0: Absolute failure — couldn't do another rep
  • RIR 1: One more rep possible (very close to failure)
  • RIR 2: Two more reps possible (hard, but not maximal)
  • RIR 3: Three more reps possible (moderate effort)
  • RIR 4+: Four or more reps possible (easy set, warm-up territory)

Why Track RIR?

RIR provides a standardized way to measure and communicate training intensity across exercises, individuals, and training phases. It solves several problems:

Quantifies Intensity

"Hard" means different things to different people. RIR 1 is objectively hard for everyone.

Enables Autoregulation

Adjust intensity based on daily performance. Feeling strong? Hit RIR 0-1. Tired? Stop at RIR 2-3.

Manages Fatigue Accumulation

Not every set needs to be RIR 0. Training at RIR 1-2 provides nearly identical stimulus with significantly less fatigue accumulation, allowing for better recovery and more productive training long-term.4

Improves Programming

Coaches can prescribe precise intensity: "3 sets of 8 reps @ RIR 2" is actionable guidance.

The Science: How Close to Failure Should You Train?

Research on proximity-to-failure and muscle growth reveals important insights:

Research Consensus:

Sets taken to RIR 0-3 produce nearly identical muscle growth, provided volume is equated. Sets with RIR 4+ produce significantly less growth.1,2,3

Key studies: Vieira et al. (2021)1, Grgic et al. (2022)2, Baz-Valle et al. (2022)3

Optimal RIR Ranges by Training Goal

Hypertrophy (Muscle Growth): RIR 0-2

Most effective range for muscle growth. Close enough to failure to recruit all motor units5, but sustainable across multiple sets and sessions.

Strength Development: RIR 1-3

Slightly further from failure to maintain bar speed and technique quality, especially on heavy compounds.

Skill Practice / Warmup: RIR 4+

Learning movement patterns or preparing for working sets. Not intended to stimulate growth.

Deload / Recovery: RIR 3-5

Intentionally submaximal to allow recovery while maintaining movement patterns.

How to Accurately Estimate RIR

Estimating RIR is a skill that improves with practice. Here's how to get better at it:

Indicators You're at RIR 0-1:

  • Bar speed significantly slows on the last 1-2 reps (the "grind")
  • Need to pause and take deep breaths before attempting another rep
  • Form starts breaking down slightly (though you should stop before major breakdown)
  • Muscles feel maximally contracted and near failure
  • You're confident you couldn't do 2 more reps

Calibration Strategy:

  1. Occasionally go to actual failure (RIR 0) to calibrate what true failure feels like
  2. Count reps on backup sets: If you estimated RIR 2 but actually did 4 more reps, adjust your perception
  3. Use velocity-based cues: When bar speed drops 20%+, you're typically at RIR 1-2
  4. Track and review: Log estimated RIR consistently and review accuracy over time

Common Mistake:

Beginners tend to overestimate RIR — what feels like RIR 2 is often RIR 4-5. It takes 6-12 weeks of consistent training to accurately perceive proximity to failure. When in doubt, push a bit closer to failure than feels comfortable.

RIR Across Different Exercise Types

Optimal RIR varies by exercise risk profile and muscle group:

Heavy Barbell Compounds (Squat, Deadlift, Bench)

Recommended RIR: 1-3

Training to absolute failure (RIR 0) on heavy compounds increases injury risk and CNS fatigue. Leave 1-2 reps in reserve for safety and technique preservation.

Machine & Cable Exercises

Recommended RIR: 0-2

Safer to push to failure. Machines provide stability and safety catches, making RIR 0 viable and productive.

Isolation Exercises (Curls, Extensions, Raises)

Recommended RIR: 0-1

Low injury risk and high tolerance for failure training. Perfect candidates for RIR 0 sets and intensification techniques like myo-reps.

Bodyweight Exercises (Pushups, Pullups)

Recommended RIR: 0-2

Generally safe to take to failure, though form quality can deteriorate on the last few reps of pushups/pullups.

Programming with RIR: Practical Applications

Example: Weekly Progression Using RIR

Exercise: Dumbbell Bench Press | 3 sets × 8-12 reps

Week 1: 50 lbs × 10 reps @ RIR 2 (could do 2 more)

Week 2: 50 lbs × 11 reps @ RIR 1 (could do 1 more)

Week 3: 50 lbs × 12 reps @ RIR 0-1 (at or very close to failure)

Week 4: 55 lbs × 8 reps @ RIR 2 (increase weight, start cycle again)

Set-to-Set RIR Management

Fatigue accumulates across sets. Strategic RIR management optimizes total training quality:

  • Set 1: RIR 2-3 (preserve energy)
  • Set 2: RIR 1-2 (push harder)
  • Set 3: RIR 0-1 (all-out final set)

This "ascending intensity" approach maximizes total quality reps while finishing with a maximal stimulus.

RIR vs RPE: What's the Difference?

RIR and RPE (Rate of Perceived Exertion) are related but distinct:

RIR (Reps in Reserve)

Objective measure based on capability: "How many more reps could I do?"
Scale: 0 (failure) to 5+ (very easy)

RPE (Rate of Perceived Exertion)

Subjective measure of effort: "How hard did this feel?"
Scale: 1 (very easy) to 10 (maximal effort)
Note: RPE 10 ≈ RIR 0, RPE 9 ≈ RIR 1, RPE 8 ≈ RIR 2

Track RIR Automatically with MVP

Minimum Viable Pump makes RIR tracking effortless. Quick-tap buttons let you log RIR in seconds, and the app uses this data to calculate your MVP Score (efficiency metric) and adjust progression recommendations based on proximity to failure.

Learn More About MVPRead FAQs

Scientific References

  1. Vieira, J. G., et al. (2021). The effect of training to failure on muscle hypertrophy: A systematic review and meta-analysis. International Journal of Environmental Research and Public Health, 18(23), 12553.
  2. Grgic, J., et al. (2022). Effects of resistance training performed to repetition failure or non-failure on muscular strength and hypertrophy: A systematic review and meta-analysis. Journal of Sport and Health Science, 11(2), 202-211.
  3. Baz-Valle, E., et al. (2022). Proximity to failure and total repetitions performed in a set influences accuracy of intraset repetitions in reserve-based rating of perceived exertion. Journal of Strength and Conditioning Research, 36(4), 1004-1011.
  4. Schoenfeld, B. J., et al. (2021). Resistance training volume enhances muscle hypertrophy but not strength in trained men. Medicine and Science in Sports and Exercise, 51(1), 94-103.
  5. Henneman, E., Somjen, G., & Carpenter, D. O. (1965). Functional significance of cell size in spinal motoneurons. Journal of Neurophysiology, 28(3), 560-580.
  6. Zourdos, M. C., et al. (2016). Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. Journal of Strength and Conditioning Research, 30(1), 267-275.
  7. Helms, E. R., et al. (2016). Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training. Strength and Conditioning Journal, 38(4), 42-49.

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