The Optimal Rep Range for Serious Muscle Growth

We’ve all heard that the 8-12 rep range is the sweet spot for hypertrophy, but here’s the truth: muscle growth can occur across a wide range of reps—as long as sets are taken close to failure. However, there is an optimal rep range you might want to focus on for more effective and sustainable gains.

Why? It all comes down to managing fatigue.

  Fatigue is a temporary and reversible drop in exercise performance. It can occur during or after exercise and stems from several factors:

- Loss of coordination

- Reduced central motor command (the brain’s signal to recruit motor units)

- Muscle fatigue from metabolite buildup (like lactate and hydrogen ions)

Here’s something I used to believe: that low reps with heavy weights caused Central Nervous System (CNS) fatigue. But that’s actually not the case. It’s higher reps with lighter loads that are more fatiguing for the CNS.

If you caught my previous email on mechanical tension, you know that for a muscle to grow, it must be active under tension—and the best way to recruit more motor units is by lifting heavy with high effort.

We know that fatigue reduces motor unit recruitment, which limits mechanical tension—the most important factor for muscle growth. Higher reps (12+) cause greater fatigue, even when working to failure. This fatigue reduces your body’s ability to recruit motor units effectively, meaning you get a weaker muscle-building response.

**On top of that, higher fatigue makes it harder to recover between sessions, which limits how often you can train effectively throughout the week.**

So, what’s the sweet spot?

Aim for 5-8 reps per set.

This range demands high effort and recruits a large number of motor units.

It minimizes fatigue, especially compared to high-rep sets, meaning faster recovery and more consistent training sessions.

Over time, this leads to better gains session to session, week to week, and month to month.

The key is making sure those last few reps slow down involuntarily, showing that you’re working close to failure (0-5 reps away from task failure). That’s when you’re creating the best stimulus for muscle growth.

Of course not. Higher-rep sets have their place, but if your goal is to build as much muscle as possible, keeping most of your sets in the 5-8 rep range gives you the best balance between stimulus and recovery.

So before you jump into that massive drop set or 50-rep pump session, ask yourself:

Is the savage DOMS really worth it? You know I am a firm believer in 70% every day, rather than 110% twice a week :)

Hope that helps.