A person lifting a barbell with a calm, focused expression, surrounded by subtle visual cues of moderation and sustainability, like a gentle gradient or soft lighting.
For decades, the gym mantra has been ‘no pain, no gain.’ We’ve been told that to build strength and muscle, you must push every set to the absolute brink of failure, where your muscles scream and you can’t perform one more rep. But what if that’s not entirely true? What if you could get stronger while leaving a little in the tank?
Recent sports science research suggests that you absolutely can. The key lies in understanding a concept called ‘repetitions in reserve’ (RIR) and recognizing that training to failure is not a requirement for progress—it’s just one tool among many. This article explores the evidence behind submaximal training, why it might be a smarter approach for most people, and how you can apply it to your own workouts.
The Myth of Mandatory Failure
The idea that you must train to failure to see results is deeply ingrained in fitness culture. It was popularized in the 1970s and 80s by figures like Arthur Jones and Mike Mentzer, who championed high-intensity, single-set-to-failure routines. Their philosophy still echoes in gyms and on social media today, where influencers scream about ‘killing it’ and ‘leaving it all on the floor.’
But modern sports science tells a different story. A 2021 meta-analysis published in Sports Medicine by Vieira and colleagues found no significant difference in muscle growth or strength between training to failure and non-failure protocols, as long as the overall training volume (sets × reps × load) was matched. A 2023 systematic review by Robinson et al. reached similar conclusions, noting that while failure training might offer a slight edge for smaller muscle groups, it can actually be inferior for overall volume accumulation due to increased fatigue.
In other words, you can stop a set with 2–4 reps still in the tank and still get the same gains as someone who grinds out every last rep. This is liberating news for anyone who dreads the burn or struggles with recovery.
Understanding RIR and RPE
To train submaximally, you need a way to measure your effort. Two tools are commonly used:
- Repetitions in Reserve (RIR): This is a self-reported measure of how many more reps you could have performed. An RIR of 2 means you stopped when you had 2 reps left in the tank. An RIR of 0 means you hit failure.
- Rate of Perceived Exertion (RPE): This is a 1–10 scale where 10 is maximal effort. An RPE of 7–8 roughly corresponds to an RIR of 2–3.
Most evidence-based coaches prescribe RIR 1–3 for hypertrophy work. For example, if you’re doing a set of 10 reps, you’d choose a weight that allows you to stop at rep 7 or 8 while still being able to do 2–3 more. This ensures you’re working hard enough to stimulate growth, but not so hard that you compromise recovery.
Why Submaximal Training Works
Strength gains come from two primary mechanisms: neural adaptations (improved motor unit recruitment, firing rate, and coordination) and muscle cross-sectional area (hypertrophy). Both are stimulated well before you reach failure. The stimulus threshold—the point at which your body decides to adapt—is lower than the failure point.
High-threshold motor units, which are responsible for maximal force production, are recruited when you lift heavy or when you push close to failure. But research shows that at RIR 2–3, you’re still recruiting nearly all of these motor units. You don’t need to hit failure to activate them; you just need to be close.
Volume is the primary driver of hypertrophy. Multiple sets (e.g., 10–20 working sets per muscle group per week) matter more than taking each set to failure. Submaximal training allows you to accumulate more total volume because recovery is faster. When you train to failure, you increase muscle damage, systemic fatigue, and central nervous system depletion, which can impair your next session. By leaving a few reps in reserve, you can train more frequently and with better quality.
The Practical Benefits of Backing Off
Training submaximally isn’t just about science—it has real-world benefits that can make your fitness journey more sustainable:
- Better Recovery: You’ll feel less beat up, which means you can train more often and with higher quality.
- Reduced Injury Risk: Pushing to failure can lead to technique breakdown, especially on compound lifts like squats and deadlifts. Stopping earlier keeps your form tight.
- Improved Performance: Powerlifters and Olympic lifters rarely train to failure on main lifts because fatigue compromises bar speed and skill. Submaximal training preserves neural freshness.
- Psychological Sustainability: Let’s face it—training to failure is mentally draining. Knowing you don’t have to grind every set makes workouts more enjoyable and easier to stick with long-term.
When to Use Failure (and When Not To)
Failure is not the enemy; it’s a tool. Here’s how to use it wisely:
- Use failure sparingly: Reserve it for isolation exercises (like lateral raises or calf raises) or the last set of an exercise, where fatigue is less likely to compromise safety.
- Avoid failure on heavy compounds: For squats, deadlifts, and bench press, stopping with 2–3 RIR is safer and still effective.
- Consider your experience level: Beginners make rapid gains even with submaximal loads (60–70% of 1RM). Advanced lifters need higher intensity and volume, but even they don’t need failure on every set.
- Listen to your body: Some days you’ll feel great and can push closer to failure; other days, you’ll be tired and should stop earlier. This is called autoregulation, and it’s a smart way to train.
The Bottom Line
You don’t need to push yourself to the limit to get stronger. Research consistently shows that training with 2–4 reps in reserve produces similar gains to training to failure, as long as you’re doing enough volume. So the next time you’re tempted to grind out that last rep, remember: you can leave it in the tank and still make progress. Your muscles—and your sanity—will thank you.
The ‘no pain, no gain’ mantra is outdated. Modern sports science shows that you can build strength and muscle without constantly flirting with failure. By using RIR to gauge your effort, you can train smarter, recover faster, and achieve results that are just as good—if not better—than those who push every set to the brink. So give yourself permission to back off a little. Your future self will thank you.
Summary
- Strength gains don’t require training to failure. Research shows similar results with 2–4 reps in reserve (RIR) as with failure, provided volume is matched.
- RIR and RPE are practical tools to measure effort and autoregulate your training based on daily readiness.
- Volume is the primary driver of hypertrophy, and submaximal training allows you to accumulate more volume with faster recovery.
- Submaximal training reduces injury risk, fatigue, and burnout, making it more sustainable for most people.
- Use failure strategically, not as a default—reserve it for isolation exercises or final sets, and avoid it on heavy compounds.
FAQ
Q: What is ‘repetitions in reserve’ (RIR)?
A: RIR is a self-reported measure of how many more reps you could have performed. An RIR of 2 means you stopped when you had 2 reps left in the tank. It’s a way to gauge effort without going to failure.
Q: How do I know if I’m training at the right intensity?
A: Use the RPE scale (1–10). For most hypertrophy work, aim for RPE 7–8, which corresponds to RIR 2–3. You should feel challenged but not completely exhausted.
Q: Will I still build muscle if I don’t train to failure?
A: Yes. A 2021 meta-analysis found no significant difference in muscle growth or strength between failure and non-failure training when volume is matched. The stimulus threshold is lower than the failure point.
Q: When should I train to failure?
A: Use failure sparingly—on isolation exercises or the last set of a movement. Avoid it on heavy compound lifts like squats and deadlifts, where technique breakdown increases injury risk.
Q: Is submaximal training suitable for beginners?
A: Absolutely. Beginners make rapid gains even with submaximal loads (60–70% of 1RM). It’s a safer and more sustainable way to build a foundation.