Training to failure is one of the most hotly debated topics in strength and hypertrophy research. Some lifters swear by it, others avoid it entirely, and many fall somewhere in between. But what does the science actually say about whether reaching failure is necessary for maximizing muscle growth?
This article breaks down the evidence clearly and simply. No fluff, no jargon, just research-backed facts presented in a friendly and easy-to-understand way.
What Is “Training to Failure”?
Training to failure means performing a set until you can no longer complete another repetition with proper form. Scientists typically distinguish between two types of failure:
Momentary Muscular Failure (MMF)
This is the strict definition used in most research. MMF means you attempt a rep, but physically cannot complete it despite maximal effort.
Technical Failure
This means stopping the set when you can no longer complete another rep with correct form, even if you could physically grind out an ugly rep.
Both concepts matter because many lifters believe they must hit true failure to stimulate the maximum amount of muscle growth. But the science paints a more nuanced picture.
Why Do People Think Training to Failure Is Essential?
There are two common arguments:
- Failure supposedly activates more muscle fibers, especially high-threshold motor units.
- Failure is believed to maximize metabolic stress, which some think enhances hypertrophy.
These ideas aren’t entirely wrong, but they aren’t fully accurate either. Research shows that muscle fiber activation increases as a set gets close to failure, but you don’t necessarily need to reach failure to achieve full recruitment. Likewise, metabolic stress contributes to hypertrophy, but it’s only one part of a larger picture.
To understand the role of failure training, we need to look at how muscle growth actually works.
The Science of Hypertrophy and Where Failure Fits In
Muscle growth relies on three core factors:
1. Mechanical Tension
This is the force applied to muscles during resistance training. It’s one of the most important drivers of hypertrophy.
2. Muscle Fiber Recruitment
High-threshold motor units—those responsible for bigger, stronger muscle fibers—activate as effort increases.
3. Accumulating Fatigue and Metabolic Stress
Training close to failure increases effort and fatigue, which can amplify the muscle-building signal.
The key point: muscle growth depends on effort, but effort does not necessarily mean reaching failure.
What the Research Says About Training to Failure
Failure Can Increase Hypertrophy—But Not Always
Several studies have tested whether sets taken to failure lead to greater muscle growth than stopping slightly short.
A landmark meta-analysis by Schoenfeld et al.(2019) found that training to failure and training short of failure produced similar hypertrophy overall, provided the total volume was equal. The only time failure seemed to matter was when total volume was low. In other words, if you’re only doing a few sets, going to failure might help compensate for lower volume.
Another study by Sampson and Groeller(2016) examined how muscle activation increased as lifters approached failure. They found that activation ramped up significantly in the final reps but wasn’t dependent on reaching true failure.
Stopping 1–3 Reps Shy of Failure Produces Similar Growth
Research on “reps in reserve”(RIR) shows that stopping around 0–3 RIR produces near-maximal fiber recruitment and hypertrophy. Pareja-Blanco et al.(2017) showed that leaving 2–3 reps in the tank maintained performance, strength gain, and muscle size while reducing excessive fatigue.
In other words, you don’t need to go all the way to failure to grow, but you need to get close enough that the set becomes challenging.
Failure Training Increases Fatigue and Recovery Time
Taking every set to failure creates more neuromuscular fatigue. Morán-Navarro et al.(2019) demonstrated significantly higher perceived exertion and longer recovery times in failure-training groups compared with non-failure groups.
This extra fatigue can reduce performance in later sets and may limit weekly training volume—one of the most important factors in long-term hypertrophy.
When Training to Failure Can Be Useful
Although failure training isn’t mandatory, it does have strategic uses.
1. When Training With Light Loads
If you’re using very light weights (e.g., 30–40% of 1RM), research shows you must train close to or at failure to recruit enough muscle fibers to stimulate growth. A study by Morton et al.(2016) found that low-load training produced hypertrophy equal to high-load training only when sets were taken to failure.
2. When Total Volume Is Limited
If you have very limited time or equipment—for example, during travel or home workouts—using failure can increase training stimulus per set.
3. When You Want to Measure True Strength Endurance
Going to failure occasionally helps gauge how many reps you can perform with a certain load. This can improve accuracy when using RIR-based programming.
4. When You’re an Advanced Lifter
More experienced athletes sometimes need higher stimulus to continue progressing. Periodic sets to failure may help advanced trainees overcome plateaus by increasing intensity.
When Training to Failure Is Not Ideal
1. For Beginners
Failure training requires body awareness and good technique. Beginners benefit more from learning form, gradually increasing intensity, and building consistent habits.
2. When Using Heavy Loads
Training to failure with heavy loads significantly increases injury risk and fatigue. Helms et al.(2018) recommend keeping 1–3 RIR for most heavy compound lifts.
3. When You Have High Training Volume
If you’re already training multiple times per week with moderate to high volume, constantly pushing to failure can impair recovery and lower performance.
How Close to Failure Do You Need to Train?
Most evidence suggests that:
Training within 1–3 reps of failure (1–3 RIR) is enough to maximize hypertrophy for most people.
A study by Lasevicius et al.(2019) comparing training at 0 RIR vs. 3 RIR found no significant differences in hypertrophy when total volume was equalized.
The “sweet spot” seems to be:
- Hard sets
- Effort rising steadily
- Final reps near technical breakdown
- Stopping before form collapses
This provides the benefits of high effort without unnecessary fatigue.
The Role of RPE and Reps in Reserve (RIR)
Using RIR or RPE helps quantify effort.
- RPE 10 / 0 RIR: Maximum effort, true failure
- RPE 9 / 1 RIR: Could have done one more rep
- RPE 8 / 2 RIR: Moderate–high effort
- RPE 7 / 3 RIR: Moderate effort
Research shows RPE 8–10 and RIR 0–3 all produce significant hypertrophy. Most lifters benefit from cycling intensity across training blocks.
Practical Guidelines for Using Failure Training
1. Use Failure Sparingly—Not Every Set
Most studies suggest 1–2 failure sets per muscle per session is plenty for intermediates or advanced lifters.
2. Use Failure on Safe, Controlled Exercises
Best exercises for failure:
- Machine presses
- Leg press
- Cable rows
- Lat pulldowns
- Dumbbell isolation lifts
- Bodyweight movements with low risk
Avoid failure with high-risk lifts:
- Squats
- Deadlifts
- Barbell bench press
- Bent-over rows
3. Keep Most Working Sets Close to Failure, Not At It
The most sustainable approach is keeping most sets in the 1–3 RIR range.
4. Use Periodization
Alternate phases:
- High-effort but non-failure training for 4–6 weeks
- Short phases including failure sets for 1–2 weeks
This prevents burnout and maintains long-term progress.
5. Pay Attention to Signs of Excessive Fatigue
Indicators you’re overusing failure:
- Declining performance
- Joint pain
- Poor sleep
- Interrupted workouts
- Persistent soreness
Failure training should enhance results, not sabotage them.
Does Failure Training Build More Strength?
Strength and hypertrophy overlap, but they aren’t the same. Strength depends heavily on technique and neural adaptations. Because failure training causes more fatigue, it can interfere with practicing heavy lifts.
Research by Izquierdo et al.(2006) found non-failure groups made larger strength gains despite equal hypertrophy.
For maximum strength:
- Train near but not at failure (1–3 RIR)
- Use heavier loads
- Maintain high-quality reps
Failure is not required and may even be counterproductive.
The Bottom Line: Is Failure Necessary?
No—training to failure is not necessary for muscle growth.
The majority of scientific evidence clearly shows:
- Sets taken close to failure (1–3 RIR) stimulate nearly identical hypertrophy compared to failure.
- Failure can help in specific contexts—like low-load training, limited time, or advanced plateaus.
- Training to failure too often increases fatigue, reduces performance, and may impair long-term progress.
The most effective and sustainable approach is mixing strategies:
- Train hard and close to failure most of the time.
- Use failure sparingly and strategically.
- Keep volume and recovery in balance.
If you enjoy pushing to failure and it doesn’t hurt your recovery, there’s nothing wrong with including it. But if you think it’s the only path to bigger muscles, the science says otherwise.
Bibliography
- Helms,E.,Grgic,J.,Schoenfeld,B.(2018)‘Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation’,Journal of the International Society of Sports Nutrition,15(1),pp.1–20.
- Izquierdo,M.,Ibañez,J.,Gorostiaga,E.,González-Badillo,J.,Häkkinen,K.(2006)‘Effects of training to failure versus not to failure on strength, power,and hormonal adaptations in trained athletes’,Journal of Strength and Conditioning Research,20(3),pp.639–643.
- Lasevicius,T.,Schoenfeld,B.,Grgic,J.,et al.(2019)‘Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy’,Journal of Strength and Conditioning Research,33(1),pp.48–56.
