A July 2026 meta-analysis found no statistically significant muscle-growth advantage from taking resistance-training sets all the way to failure. So what does that mean for cable crunches, weighted crunches and the last ugly rep of your ab workout?
The newest meta-analysis found no significant hypertrophy advantage for failure training versus stopping short. Non-failure training actually produced a small advantage for dynamic strength.
That does not mean you should stop every cable crunch while it still feels easy. Other research suggests muscle growth tends to improve as sets are performed closer to failure. The distinction is between training hard and being forced to fail every set.
Important nuance: the hypertrophy analysis itself used 10 publications. The full set of 20 studies covered strength, hypertrophy, endurance and power outcomes.
The new meta-analysis does not show an extra hypertrophy payoff from reaching failure.
Researchers pooled randomized controlled trials comparing resistance training performed to failure with resistance training that deliberately stopped short. The participants were healthy adults with a wide range of training backgrounds, and the programs lasted roughly four to fourteen weeks.
Randomized controlled studies in the complete review.
Healthy adults ranging from untrained to elite athletes.
Pooled effect size for non-failure versus failure; not statistically significant.
Small statistically significant advantage for non-failure training.
| Outcome | Pooled result | Statistically significant? | Practical reading |
|---|---|---|---|
| Dynamic strength | SMD 0.24 | Yes — favored non-failure | Stopping short produced a small advantage in dynamic strength. |
| Muscle hypertrophy | ES −0.15 | No | No evidence that failure produced meaningfully greater muscle growth overall. |
| Isometric strength | SMD −0.12 | No | Neither approach showed a clear advantage. |
| Muscular endurance | SMD −0.02 | No | Going to failure did not clearly improve endurance adaptations. |
| Muscular power | SMD 0.02 | No | Essentially no pooled difference. |
Twenty studies were included in the complete meta-analysis, but not every study measured every outcome. The hypertrophy analysis was based on 10 publications. The review also studied strength, endurance and power, so it would be inaccurate to say that 20 hypertrophy studies specifically showed no difference.
This was broad resistance-training evidence—not an ab-specific trial.
The included experiments used exercises such as squats, knee extensions, bench presses and deadlifts. The review contained upper-body, lower-body and whole-body protocols, but it did not report a direct weighted-crunch or cable-crunch experiment.
The sample included sedentary adults, recreationally active lifters, highly trained participants and elite athletes.
The authors rated the evidence for the analyzed outcomes as moderate using the GRADE framework. Several included studies still had methodological concerns.
“Don’t train to failure” does not mean “stop when the set gets uncomfortable.”
Repetitions in reserve—usually shortened to RIR—is a simple way to describe how many additional clean repetitions you believe you could have completed before failure.
Far from failure
You finish the set knowing several strong repetitions were still available. Useful for warm-ups and technique work, but may be too easy for some hypertrophy-focused work.
Hard, controlled work
The 2026 ACSM Position Stand points to approximately 2–3 RIR as a practical near-failure target that can provide sufficient effort without requiring absolute failure.
Very close
One additional clean repetition probably remains. This is an extremely hard set and can provide a high-effort stimulus without necessarily reaching failure.
Failure
No additional concentric repetition can be completed with the prescribed technique. Fatigue is highest here, but the evidence does not show that every set must reach this point.
People often get better at estimating RIR with training experience, and accuracy can vary by exercise. Treat RIR as a practical training gauge rather than laboratory precision.
Failure may not be required—but proximity to failure probably still matters.
A separate 2024 meta-regression analyzed estimated proximity to failure across resistance-training studies. Muscle hypertrophy tended to increase as sets were terminated closer to failure, although the relationship was not perfectly linear and estimating RIR across older studies introduces uncertainty.
Ten reps left is not the same as two.
The fact that absolute failure is unnecessary should not be used as permission to make every hypertrophy set comfortable.
Hard sets can recruit the fibers you are trying to train.
Stopping roughly one to three clean repetitions short gives you a hard training stimulus without requiring the final failed attempt.
The final rep may cost more fatigue than stimulus.
Failure can be useful selectively, but repeatedly grinding until a rep physically stalls may create recovery cost without a proven hypertrophy bonus.
The last failed rep is not free.
Acute research consistently shows that sets taken all the way to failure produce more immediate fatigue than sets stopped short. That matters because your ab workout is rarely the only thing you need to recover from.
One direct RIR experiment makes the difference easy to see.
In resistance-trained men and women performing six bench-press sets at 75% 1RM, post-workout lifting velocity dropped about 25% after failure training, versus 13% at 1 RIR and 8% at 3 RIR. That was an upper-body experiment—not an ab study—but it demonstrates the fatigue gradient.
Weighted crunches are a good place to stop confusing pain with productivity.
A cable crunch or progressively loaded crunch can be trained much like another resistance exercise: choose a controllable resistance, perform hard sets through a consistent range of motion and progressively increase the challenge over time.
| Ab-training situation | Better default | Reason |
|---|---|---|
| Heavy cable crunches | Usually stop around 1–3 RIR | Lets you maintain trunk position and progress resistance without making every set a form breakdown test. |
| Moderate weighted crunches | 1–3 RIR for most sets | Hard enough for a substantial stimulus while controlling accumulated fatigue. |
| Final set of a safe isolation movement | Failure can be optional | A controlled final-set failure can be used if you enjoy it and recovery is good, but the evidence does not say it is required. |
| Bodyweight crunches that feel extremely easy | Add difficulty before chasing failure forever | Increase resistance, leverage or range rather than relying on endless repetitions solely to reach exhaustion. |
| Reps become jerky or hip-dominant | End the set | “Failure” after the target exercise has disappeared is no longer the same stimulus you were trying to train. |
Compare the approaches without turning four weeks into a recovery contest.
This is an editorial training experiment informed by the resistance- training literature. It was not tested as an ab-specific clinical trial. Use the same cable crunch or weighted crunch throughout so that the main variable you change is proximity to failure.
The evidence-based default.
- 2 sessions per week.
- Cable or weighted crunch.
- 3 working sets per session.
- Roughly 8–15 controlled reps.
- Stop most sets with about 2 RIR.
- Progress load when all sets hit the top of the range cleanly.
A more aggressive comparison without failing every set.
- 2 sessions per week.
- Same exercise and rep range.
- First two sets stop around 2 RIR.
- Only the final working set reaches technical failure.
- No forced reps or assisted negatives.
- Progress only when technique and recovery remain stable.
3 × 8–12 at about 3 RIR. Establish a resistance you can control without guessing at failure.
Use the same setup. Sets 1–2 at 3 RIR; final set may reach technical failure.
Move toward 2 RIR. Add reps while keeping identical range and tempo.
Sets 1–2 at 2 RIR; final set to technical failure. Record how many reps the failure set adds.
Maintain 1–2 RIR. If all three sets reach 15 clean reps, increase resistance slightly.
Keep the same progression rule, but continue taking only the final set to technical failure.
Repeat week 3. Compare load, clean reps, soreness and your ability to progress session to session.
Repeat week 3. Ask whether the failure set is creating more useful progression—or mostly more fatigue.
Write down resistance, clean repetitions, estimated RIR, whether your range of motion shortened, next-day soreness and performance at the following session. The point is not simply to discover which workout “burns more.” It is to see which approach lets you accumulate and progress high-quality abdominal work.
“Not necessary” is different from “never useful.”
The research does not show that failure destroys your gains. It shows that regularly reaching failure has not demonstrated a clear additional hypertrophy benefit over sufficiently hard non-failure training.
Learning what true failure feels like
Occasional controlled failure can calibrate your RIR estimates. Someone who thinks they stopped at 1 RIR may discover they actually had four repetitions left.
The final set of a stable exercise
If the movement is safe, technique remains controlled and recovery is good, taking an occasional last set to failure is a reasonable programming option.
Every set, every session, because “pain equals growth”
That strategy adds fatigue without evidence that the final failed repetition is mandatory for hypertrophy.
Failure training gets especially messy when technique becomes the casualty.
A burning abdomen is uncomfortable, but it does not automatically mean another clean repetition is impossible.
If the exercise changes because the target muscles are fatigued, consider the useful set finished.
The evidence against mandatory failure does not say effort is irrelevant. Hypertrophy-oriented sets should still be challenging.
A failure session may create more soreness and fatigue without producing measurably better long-term growth.
For bigger abs, “almost failure” may be the more useful default.
The July 2026 meta-analysis adds to a growing body of research showing that resistance-training sets do not have to end in absolute muscular failure to stimulate muscle growth.
That does not make easy sets equal to hard sets. The broader proximity-to-failure literature suggests that getting reasonably close to failure still matters—especially when hypertrophy is the goal.
For progressively loaded abs, a practical approach is simple: perform most working sets about 1–3 clean repetitions short of failure, progress resistance or repetitions over time, and use true failure selectively rather than automatically.
The best final rep is not necessarily the one you cannot finish. It may be the last clean rep that lets you come back and outperform yourself next session.
Sources
- Wu S, Xie L, Zhao Z, et al. Effects of resistance training performed to repetition non-failure on exercise performance in healthy adults: a systematic review and meta-analysis. BMC Sports Science, Medicine and Rehabilitation. Published July 6, 2026. Full article
- Currier BS, D’Souza AC, Fiatarone Singh MA, et al. American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews. Medicine & Science in Sports & Exercise. 2026. Full text
- Refalo MC, Helms ER, Trexler ET, Hamilton DL, Fyfe JJ. Influence of Resistance Training Proximity-to-Failure on Skeletal Muscle Hypertrophy: A Systematic Review with Meta-analysis. Sports Medicine. 2023. Full text
- Robinson ZP, Pelland JC, Remmert JF, et al. Exploring the Dose-Response Relationship Between Estimated Resistance Training Proximity to Failure, Strength Gain, and Muscle Hypertrophy: A Series of Meta-Regressions. Sports Medicine. 2024. PubMed
- Refalo MC, Helms ER, Robinson ZP, Hamilton DL, Fyfe JJ. Similar muscle hypertrophy following eight weeks of resistance training to momentary muscular failure or with repetitions-in-reserve in resistance-trained individuals. Journal of Sports Sciences. 2024. PubMed
- Refalo MC, Helms ER, Hamilton DL, Fyfe JJ. Influence of Resistance Training Proximity-to-Failure, Determined by Repetitions-in-Reserve, on Neuromuscular Fatigue in Resistance-Trained Males and Females. Sports Medicine – Open. 2023. PubMed
- Vieira JG, Sardeli AV, Dias MR, et al. Effects of Resistance Training to Muscle Failure on Acute Fatigue: A Systematic Review and Meta-Analysis. Sports Medicine. 2022. PubMed
- Grgic J, Schoenfeld BJ, Orazem J, Sabol F. 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. 2022. Full text
Research reviewed through October 20, 2026. The ab routines in this article are practical applications of general resistance-training evidence and were not directly tested in the July 2026 meta-analysis. “Failure” should refer to the inability to complete another repetition with the intended exercise technique—not forced repetitions performed through substantial form breakdown.
How close to failure should your ab set go?
Choose your exercise, experience and goal. This gives you a practical starting target—not a claim that one exact RIR number has been proven optimal for every person.
