How Close to Failure Should You Train for Muscle Growth?

Most lifters have heard the phrase “train hard or go home.” But when it comes to building muscle, do you actually need to take every set to failure? Or is there a smarter way? Let’s break down how close to failure you should train for maximum hypertrophy.

What Is Training to Failure?

Training to failure means performing a set until you physically cannot complete another rep with good form. It’s the point of complete muscular fatigue—also called momentary concentric failure.

But there’s a spectrum between stopping far from failure and going all the way:

• 5 RIR: 5 reps in reserve (you could’ve done 5 more)
• 0 RIR: true failure
• -1 RIR: you attempted a rep and failed mid-rep

Muscle Growth Comes From Effective Reps

The last 4–5 reps of a set are often the most “anabolic”—they create the most mechanical tension and motor unit recruitment. This means that to grow muscle, you need to train close to failure—but not necessarily hit it every set.

Optimal RIR for Hypertrophy

• Compound lifts: Stop ~1–2 reps shy of failure. Going to failure on heavy barbell lifts increases fatigue and injury risk.
• Isolation lifts: Going to or very close to failure (0–1 RIR) is more manageable and effective.
• High-rep sets (15–30 reps): These MUST go close to failure to be effective. Otherwise, they become endurance work.

Benefits of Not Going to Failure Every Time

While training to failure can increase effort, it comes with tradeoffs:

• More fatigue accumulation
• Slower recovery between sessions
• Higher injury risk on compound lifts
• Harder to maintain performance across multiple sets

Most lifters make better long-term progress training within 0–2 RIR for most working sets.

When to Use Failure Strategically

• Last set of an isolation exercise
• Deload week with lower overall volume
• AMRAP sets for testing or motivation
• In machine-based training blocks with minimal compound loading

FAQ

Should I train to failure on every set?

No. This leads to excessive fatigue and often reduces total training quality. Most sets should stop 1–2 reps shy of failure.

How do I know how many reps I have in reserve?

Start by videoing your sets and comparing bar speed. With practice, you’ll learn to gauge when you’re close to true failure.

Does failure training build more muscle?

It can—but only marginally, and often at the cost of recovery. A well-balanced program near failure is usually better than all-out effort every time.

Is training to failure dangerous?

Not inherently. But doing so frequently on barbell compounds (like squats or bench) increases risk if form breaks down.

Conclusion

You don’t need to annihilate yourself every session to grow muscle—you need to apply enough stimulus consistently. For most lifters, training within 0–2 reps of failure is the sweet spot: high effort, manageable fatigue, consistent progress.

Want to get more out of each rep? Read our guide on Best Rep Ranges for Muscle Growth to stack your sets the smart way.

Sources: PubMed – Resistance Training to Failure vs Not to Failure for Muscle Growth