Science-Backed RIR Training: Build More Muscle, Smarter

Key takeaways

• You can likely leave some sets 3–4 reps from failure without losing measurable growth—if you still hit several sets near failure across the week.
• If you train low volume, you should push closer to failure (0–2 RIR). If you run higher volume, keeping most sets at 0–2 RIR still works well and a few easier sets help recovery.
• Your strength gains tolerate working further from failure more than hypertrophy does, so use RIR strategically based on whether you want more muscle or more strength.

Want to squeeze more muscle out of smarter, less brutal training?

In this expert review, we analyze, critique, and expand on House of Hypertrophy's video and the new paper they covered. We walk through the study design, the results, what they mean, and how you can use this to tune your own training.

What makes this review different and why should you listen to us?

• Our experts carefully review and fact-check based on their extensive experience publishing 300+ articles.
• We include little-known tips to apply RIR, volume, and frequency so you get more muscle, less fat, and an improved physique.
• An expert workout mixing varied proximities to failure approved by our in-house exercise scientist with 20+ years' experience in the gym.

Keep reading. You’ll get a clear summary, a usable plan, and practical rules to test in the gym.

Related:

• How to Build Muscle as a Skinny Guy
• Reps In Reserve
• Volume & Muscle Hypertrophy

In a Nutshell: Proximity to failure

You can keep some sets a few reps shy of failure. But you must still include sets close to failure if you want maximal hypertrophy. When you run low total volume, push closer to failure. When you run moderate or high volume, you can spread effort differently and still grow.

Key concepts

• Reps in Reserve (RIR): How many reps you stop short of failure. Low RIR (0–2) maximizes fiber stress per set.
• Volume-effort tradeoff: More total volume reduces the need for every set to be to failure. You can manage fatigue by mixing RIR.
• Task specificity for strength: Strength gains tolerate higher RIR better than hypertrophy does.

Why this new study matters and what it tested

Let me cut to the chase. You want to know how close to failure you must train to get bigger and stronger. Coaches and lifters argue a lot. Some say train to failure. Some say never. The middle ground is RIR—reps in reserve.

This new study targeted trained lifters. That matters. Trained people respond differently from beginners. The study split participants into two groups. Both groups followed the same upper–lower program for two 4-week blocks. One group kept every set at 1 RIR. The other group varied RIR across weeks: week 1 = 4 RIR on all sets, week 2 = 3 RIR, week 3 = 2 RIR, week 4 = 1 RIR. Then they deloaded and repeated the cycle. The researchers measured muscle size of the vastus lateralis and triceps, and 1RM bench and squat.

Why is that design interesting? Because it compares a fixed near-failure strategy (1 RIR every set) with a planned variation across the mesocycle. The varied group spends some time further from failure, but they still end each block with sets close to failure.

Who the subjects were

31 trained lifters. They had at least 2 years of experience. That makes the sample relevant to lifters who already have a good training base. They were not novices. This matters because beginners often grow with any reasonable stimulus. Trained people force you to test the details.

Program structure

• Upper–lower split across the study.
• Two 4-week blocks that were nearly identical for both groups.
• Fixed group: 1 RIR on all sets across weeks.
• Varied group: Week 1 = 4 RIR, Week 2 = 3 RIR, Week 3 = 2 RIR, Week 4 = 1 RIR. Then deload (volume/frequency halved; all sets 1 RIR).

This structure gives you a real test of whether some lighter sets matter if you still perform some sets near failure.

Did they trust the lifters to estimate RIR?

Good question. RPE and RIR depend on accurate self-monitoring. The researchers tested the subjects’ accuracy. They made each lifter do reps to failure at 80% 1RM on squat and bench. During the set, the lifters shouted when they thought they had 3 reps left and when they thought they had 1 rep left. Then they kept going to failure. Researchers measured the difference.

Results: on average, lifters were fairly accurate. The biggest mean error was -1.5 reps for estimating 3 RIR on the squat. That means if someone said “3 RIR,” they went on to do 4.5 more reps. After the study, they retested, and accuracy improved slightly. Mean errors shrank toward -1 or even zero for some tests.

So yes, the lifters were decent at estimating RIR for main lifts. But remember: they tested only squat and bench. The program used many other exercises. Accuracy likely varied across those. You will be better at estimating RIR on simple barbell lifts and poor on unilateral or technically complex moves.

Main findings

• No significant difference in growth of vastus lateralis cross-sectional area between groups.
• No significant difference in triceps thickness between groups, though triceps growth numerically favored the varied group.
• No significant difference in squat or bench 1RM gains between groups overall. For men, bench gains slightly favored the fixed 1 RIR group.

This suggests that including some sets a bit further from failure might not harm your gains—at least in the short 8-week model used here. It also suggests that whether you lock every set to 1 RIR or vary RIR across microcycles may not drive big differences in muscle size for trained lifters over a relatively short period.

What to watch for: limitations and nuance

Don’t overread the result. This is one study. It had 31 participants. It was partly unsupervised. Researchers only supervised week 4. Lifters logged sessions and filmed a couple of sets. That’s decent, but not perfect.

RIR accuracy varies. The group averages looked okay, but individual data showed some lifters were off. Tests were only on bench and squat. We can’t be sure how accurate RIR was on Bulgarian split squats, incline dumbbell curls, or other accessory lifts.

Also, the study had no group that trained all sets to failure (0 RIR). You could infer from prior research that 0 RIR vs 1 RIR often shows no large difference. But this study doesn’t directly test training to failure versus not.

Finally, duration. Two four-week blocks plus deloads give you only a short-term view. Some effects may take longer to appear. So use this trial as an informative nudge, not a final verdict.

What prior research says about failure and growth

Let me put this study in the context of what we already know. The weight of evidence shows a nuanced picture. Across many studies and meta-analyses, effort matters for hypertrophy. But volume matters more.

• If you train with low volume, you may need to push closer to failure to recruit high-threshold motor units and produce enough stimulus. In short: low volume = higher intensity per set.
• If you train with moderate to high volume, you can likely stop 1–2 reps short of failure on most sets and still grow well. The extra sets make up for the slightly lower per-set stimulus.
• For strength, proximity to failure matters less. You can make good strength gains training further from failure and focusing on heavy loads and progressive overload.

That is my current working model. It’s simple and practical. Use 0–2 RIR as your default for hypertrophy. Use slightly further from failure when volume is high or when you’re managing fatigue. Save training to absolute failure for specific sessions or small muscles where technique is less compromised.

How to apply this to your training

You want rules you can use tomorrow. Here’s a short set of rules based on the study and the body of research:

• Default for hypertrophy: aim for 0–2 RIR on most sets, especially compound lifts and prime movers.
• If you run high weekly volume for a muscle, allow some sets at 3–4 RIR to manage fatigue and recovery.
• On low-volume programs (fewer sets per muscle group per week), push closer to failure on most sets.
• For strength-specific phases, you can leave more RIR and still gain strength, as long as you progressively overload over time.
• Use deloads and planned lighter weeks to recover. That helps you maintain or raise intensity later.

How to coach your RIR in practice

Estimating RIR takes practice. You get better quick on big barbell lifts. For curls, leg extensions, and machine moves, you’ll be more accurate faster.

Some tips to sharpen your RIR:

• Occasionally take a set to failure (every 6–12 workouts) to calibrate your RIR perception.
• When you hit a weight for the first time, be conservative and leave more RIR; refine as you repeat the set across sessions.
• Watch for cheating or form breakdown. If your form fails first, you haven’t reached true muscular failure—stop earlier or regress load.
• Record one working set per week and review it. Video feedback improves RIR accuracy.

When to intentionally use sets further from failure

There are sensible reasons to back off from failure sometimes:

• High-volume specialization blocks: when you attack one muscle with 15–25 sets per week, using some 3–4 RIR sets helps you adapt to volume without burning out.
• Low-energy days: a session with less sleep, poor nutrition, or high stress. It’s better to do a useful session at 3–4 RIR than skip it.
• Technique-focused training: use higher RIR when you need to preserve form and nervous system integrity.

When to be strict: situations to stay at 0–2 RIR

• Low weekly volume: push closer to failure to make each set count.
• Short-term goals to peak for a test: when you want a quick strength or size bump, be stricter on RIR.
• Small muscle groups where high effort per set matters (e.g., calves, triceps). They tolerate more near-failure work.

Hybrid RIR Upper/Lower Training Program

This plan is inspired by the study’s insight: you can mix RIR across microcycles and still progress. Use it if you want more muscle without killing yourself every set. It balances work and recovery.

Overview

• Inspired by: House of Hypertrophy
• Key insight: vary proximity to failure across weeks but keep a block with low RIR to ensure high fiber recruitment.
• Duration: 8 weeks (two 4-week blocks with a deload week after each block)

Ideal for

• Intermediate lifters with 2+ years of training experience
• People who want to build muscle with manageable fatigue
• Lifters who want to learn and practice RIR

Equipment needed

• Barbell and plates
• Power rack
• Dumbbells
• Bench
• Optional machines or cables

Workout Split

• Upper A / Lower A / Rest / Upper B / Lower B / Rest / Rest
• 4 sessions per week
• Progress weekly: add 1–5% load or 1 rep to compound lifts when you hit top of rep range for all sets

Block structure

• Block 1 (Weeks 1–4): Week 1 = 4 RIR, Week 2 = 3 RIR, Week 3 = 2 RIR, Week 4 = 1 RIR
• Deload: Week 5 — halve volume and set RIR to 1 for each set
• Block 2 (Weeks 6–9): repeat Block 1
• Final deload: Week 10 — recovery week

Upper A

• Barbell Bench Press — 4 sets × 6–8 reps — Rest 2–3 min
• Incline Dumbbell Press — 3 sets × 8–10 reps — Rest 90–120 sec
• Pendlay Row or Barbell Row — 4 sets × 6–8 reps — Rest 2–3 min
• Face Pulls — 3 sets × 12–15 reps — Rest 60–90 sec
• Barbell Curl or Incline Dumbbell Curl — 3 sets × 8–12 reps — Rest 60–90 sec

Pro tips

• Keep first compound at target RIR per week. On week 4, aim for 1 RIR across sets.
• Use tempo on presses to avoid bouncing. Slow the eccentric for control.
• Rows should be performed hard but with solid scapular control—no jerking.

Lower A

• Back Squat — 4 sets × 6–8 reps — Rest 2–3 min
• Romanian Deadlift — 3 sets × 8–10 reps — Rest 2 min
• Bulgarian Split Squat — 3 sets × 10–12 reps per leg — Rest 90–120 sec
• Leg Curl (machine) — 3 sets × 12–15 reps — Rest 60–90 sec
• Standing Calf Raise — 3 sets × 10–15 reps — Rest 60–90 sec

Pro tips

• Squats first. Push RIR target for the day. Keep form tight.
• Romanian deadlifts should be hip-dominant—feel hamstrings and glutes.
• Use a weight that lets you reach top of rep range at the prescribed RIR.

Upper B

• Overhead Press — 4 sets × 6–8 reps — Rest 2–3 min
• Weighted Pull-Ups or Lat Pulldown — 4 sets × 6–8 reps — Rest 2–3 min
• Flat Dumbbell Press — 3 sets × 8–10 reps — Rest 90–120 sec
• Lateral Raises — 3 sets × 12–15 reps — Rest 60–90 sec
• Triceps Rope Pushdown — 3 sets × 10–12 reps — Rest 60–90 sec

Pro tips

• Press heavy early in the session. Keep triceps work later for pump and fatigue management.
• For pull-ups, use a full range of motion—add weight when you hit top of rep range.

Lower B

• Deadlift — 3–4 sets × 4–6 reps — Rest 2–4 min
• Front Squat or Goblet Squat — 3 sets × 8–10 reps — Rest 2 min
• Leg Press — 3 sets × 10–12 reps — Rest 90–120 sec
• Seated Calf Raise — 3 sets × 10–15 reps — Rest 60–90 sec
• Hanging Leg Raise — 3 sets × 10–15 reps — Rest 60–90 sec

Pro tips

• Deadlift is a heavy move. Keep RIR slightly higher if your nervous system is taxed, but progressively overload every session you can.
• Front squats add quad bias and help balance posterior chain work.

Notes on Program Execution

• Warm up thoroughly before working sets. Use progressive warm-up sets that resemble working set RIR.
• Track sets, reps, RIR, and load on each set. Keep a training log so you can adjust volume and intensity.
• If you miss progress on compound lifts for 2–3 sessions, back off weight or add a low-effort week.
• Use nutrition and sleep to support recovery. You won’t force growth if calories and rest are low.

This plan gives you a template to vary RIR across weeks. It ensures you still get hard sets. It also gives you breathing room so you don’t burn out every week. Use it as a cycle you can repeat and adjust.

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Expert Corner: Proven Strategies & Hidden Gems

Practical Applications

• Apply RIR calibration sets: Take one compound movement (bench, squat) to failure every 4–6 weeks to recalibrate your perception of RIR. This improves your accuracy and makes your RIR targets useful.
• Use periodized RIR blocks: Run 3–4 week ramps where RIR decreases across the mesocycle (4 → 1 RIR). This reduces accumulated fatigue during the early weeks while ensuring high-effort work before a deload.
• Combine volume and strategic RIR: If you plan 15–20 weekly sets per muscle, keep most sets at 1–2 RIR and allow 20–40% of your weekly sets at 3–4 RIR to manage recovery.

Examples:

• Example 1: If you train chest with 12 sets weekly, do 8 sets at 1–2 RIR and 4 sets at 3–4 RIR (spread across exercises).
• Example 2: During an 8-week hypertrophy block, run weeks as 4, 3, 2, 1 RIR then deload. Repeat the cycle and adjust load weekly.

Fact-Check of Key Points

• Claim: "Getting to or very close to failure ensures you maximize muscle fiber recruitment." Fact-check: This is broadly supported by physiology. High effort recruits more motor units, though cumulative volume across sets also recruits fibers over time.
• Claim: "Training with 1–2 RIR is sufficient for growth at moderate-to-high volumes." Fact-check: This aligns with multiple meta-analyses; leaving 1–2 RIR typically yields comparable hypertrophy to training to failure when volume is matched.
• Claim: "Strength gains are less sensitive to proximity to failure." Fact-check: Strength adapts through neural changes and specific heavy loading; many studies show similar strength improvements whether or not lifters reach failure frequently, as long as progressive overload occurs.
• Claim: "Subjects were fairly accurate at estimating RIR." Fact-check: Average accuracy was acceptable, but individual variance existed. Estimation tends to improve with practice and may be exercise-dependent.

More Little-Known Tips for RIR and Volume

• For small muscles (biceps, triceps), doing a final drop set or one set to failure once per week can be high value without huge systemic fatigue.
• If you have chronic low energy, reduce RIR by one on compound lifts and add a couple of easier sets for volume. This keeps stimulus while protecting recovery.
• Use cluster sets or short rest-pauses to get more effective reps close to failure without the same level of metabolic fatigue.

My Opinion on mixing RIR across cycles

I like the idea of planned variation. I think it gives you both intensity and sustainability. Varying RIR lets you manage the nervous system and metabolic load. You still hit hard sets before deloads. That mix gives you grow-orientated stress without constant maximal effort.

I disagree with the notion that you must go to failure every session. That’s a road to burnout. I also disagree with the idea that leaving lots of RIR always works. If you do too many easy sets and not enough tough ones, you’ll slow progress.

I prefer a middle path: most sets 0–2 RIR, some sets 3–4 RIR when volume or recovery demands it. Use these tactics for months, not days. Track outcomes. If growth stalls, nudge RIR down and increase the intensity of key sets.

Concluding on a practical take

Maximizing muscle and strength doesn’t require dragging yourself to failure on every set. As this research review showed, you can confidently leave some reps in reserve—especially if your weekly training volume is moderate to high. Strategic use of RIR not only supports continued muscle growth but also safeguards your recovery, consistency, and long-term progress.

Embrace a smarter approach: most of your sets should stay close to failure (0–2 RIR) for hypertrophy, but don’t fear including lighter sets (3–4 RIR) to manage fatigue and life’s curveballs. For strength, you have even more flexibility, thanks to the forgiving nature of RIR when loads and technique are on point.

Ultimately, effective muscle-building is more about applying proven, science-backed tactics throughout your training cycle than about chasing exhaustion every session. Use this evidence-based framework to optimize your routine, listen to your body, and adjust your effort as needed. The outcome? More muscle, less burnout, and steady gains you can sustain for the long haul.

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FAQ

What is reps in reserve (RIR)?

Reps in reserve is your estimate of how many reps you could still do at the end of a set. For example, if you stop a set and think you could do one more, that's 1 RIR. It helps you control effort and manage fatigue across a program.

Does training to failure build more muscle?

Training to failure can help when you run low total volume, because it ensures high motor unit recruitment. But with moderate to high volume, you can often leave 1–2 RIR on most sets and still build similar muscle over time.

How close to failure should you train for hypertrophy?

For hypertrophy, aim for 0–2 RIR on most sets as a default. If you use very high weekly volume or are managing recovery, include some sets at 3–4 RIR. Adjust based on progress and fatigue.

Can you get stronger without training to failure?

Yes. Strength gains rely on progressive overload, neural adaptation, and specific practice. You can leave several reps in reserve and still increase 1RMs over weeks and months if you raise load or reps progressively.

Is training all sets to 1 RIR better than varying RIR?

Not necessarily. A fixed 1 RIR approach is solid. A planned variation across weeks (e.g., 4→1 RIR) can reduce fatigue and still produce similar growth, especially if you hit hard sets regularly. Choose what you can sustain and measure results.

How do you estimate RIR accurately?

Calibrate by occasionally taking sets to failure every 4–6 weeks. Practice on simple lifts like bench and squat. Use video and logbooks to check your estimation. You’ll get better within a few weeks.

Should beginners use RIR?

Beginners can use simple RIR rules but they often grow with less precision. A practical approach: focus on consistent hard work, keep form, and progress load. As you become intermediate, use RIR to fine-tune effort and recovery.

How should you adjust RIR on low-energy days?

On low-energy days, leave 2–4 RIR on most sets and reduce volume slightly. Do a useful workout rather than skipping it. Use these days sparingly to protect long-term progress while preserving consistency.

We used AI to summarize the video Train EASIER for Size & Strength? This NEW Study Is Interesting while drafting this expert review.