Yes, I Said More Reps. No, I’m Not Being Mean.

The other day during a session, one of my clients asked me “Does anyone get excited when you say ‘more reps’?”

I laughed and replied, “Nobody, absolutely nobody.”

Not once has there been a moment when I originally tell a client "Let's do 12-14 reps" then bump the number up and have someone respond with "Yay!" or "I thought you'd never ask!" If anything, I'm probably the reason some clients have trust issues but in this blog I want to explain why I’m not going to let you entirely cruise in the easy zone. That doesn’t mean every set needs to end in exhaustion, but if you finish every set barely breaking a sweat, we may be missing part of the stimulus that helps you get stronger.

How heavy should we lift?

Heavy weights for fewer repetitions? Lighter weights for more repetitions? This has been the question with strength training for decades.

A recent study published in the Medicine & Science in Sports & Exercise suggests that this question may be incomplete. Instead of thinking only about load, researchers argue that we should consider two interacting parts of resistance training: Load and fatigue. (Pareja-Blanco et al., 2026).

Think of them as two dials.

The load dial controls how heavy the resistance is.

The fatigue dial controls how much your performance declines as the set continues.

What Does Fatigue Actually Mean?

During the first few repetitions of a set, the weight may move fairly easily. As the set continues, however, the working muscles gradually lose their ability to produce the same amount of force.

The repetitions start moving more slowly. That slowing is one sign that fatigue is accumulating.

Scientists can measure this using velocity loss—the percentage decrease in lifting speed from the beginning of a set to later repetitions. That fatigue may be particularly important for muscle growth.

How Does Fatigue Help Build Muscle?

Think of your muscle like a company with a large staff. At the beginning of a moderate-weight set, you don't necessarily need every employee working. Your nervous system recruits enough motor units—a motor neuron and the muscle fibers it controls—to produce the force required but as the set continues, those working fibers begin to fatigue. To keep the weight moving, your nervous system essentially says: “I need more help.”

It increases its neural drive and recruits additional motor units, including higher-threshold motor units capable of producing substantial force. Those aren't new muscle fibers. They were there all along—they simply weren't needed during the easier repetitions.

This is one reason fatigue can be useful for muscle growth. As more fibers become involved and the set becomes increasingly difficult, more of the muscle is exposed to high levels of mechanical tension, one of the major stimuli associated with hypertrophy.

Then comes the adaptation.

When this stimulus is repeated over weeks and months, the body responds in several ways. Existing muscle fibers can become larger by accumulating additional contractile proteins and myofibrils. A larger muscle generally has a greater potential to produce force because it contains more contractile machinery, however, strength is not only in the size of the muscle.

Your nervous system also gets better at using the muscle you already have—improving neural drive, motor-unit recruitment, coordination, and your ability to produce force during a specific movement. Research shows that neural adaptations can contribute substantially to strength increases, especially during resistance training.

So a simple way to picture it is:

• Fatigue recruits more of the workforce.

• Training gives that workforce a reason to adapt.

• Recovery allows the workers to become more capable.

• Repeated practice teaches the manager (i.e. the nervous system) to use them more effectively.

  
  

That combination helps explain why, over time, you can lift more weight. This helps explain why both heavier and lighter weights can stimulate hypertrophy when sets are performed with sufficient effort (Schoenfeld et al., 2017). The lighter weight itself doesn't suddenly become heavier. Instead, your fatigued muscles experience the remaining repetitions as increasingly demanding. Research examining proximity to muscular failure has similarly found that muscle hypertrophy tends to increase as sets are performed closer to failure, although reaching complete failure does not appear to be necessary (Robinson et al., 2024; Refalo et al., 2023).

What Did the New Study Find?

The researchers wanted to separate two things that usually get mixed together in resistance training: how heavy the weight is and how much fatigue builds up while lifting it.

What they found was surprisingly practical. When the goal was maximal strength, heavier weights generally produced better results but strength did not improve simply by creating more and more fatigue. A moderate amount of fatigue seemed to work best. For muscle growth, however, fatigue played a bigger role. When people trained with the same relative load, the groups that allowed more fatigue to accumulate generally experienced greater muscle growth. Muscle growth increases the size and force-producing potential of the muscle, while seeking maximal strength teaches the nervous system how to use that muscle more effectively.

That doesn't mean every set needs to end in complete failure but it does suggest that if building muscle is one of the goals, we probably shouldn't be skating by every set either. Some sets need to become genuinely challenging. Those are the moments when the repetitions slow down, additional muscle fibers are recruited to help maintain force, and more of the muscle is exposed to the high levels of effort and mechanical tension that contribute to growth.

We want to create fatigue intentionally—not constantly.

There are times when I may stop a set before you're exhausted because we're focusing on strength, power, technique, or preserving performance for the rest of the workout and there are other times when I may deliberately let a set become uncomfortable because that fatigue is part of the stimulus we're looking for.

I'm not being mean, it's because I see potential.

When I say, “Give me three more,” it's because I haven't seen the struggle we may necessarily need to activate the stimulus for strength. Those extra reps may be taking the muscle from a relatively comfortable level of effort into the portion of the set where fatigue begins recruiting more muscle fibers and making those fibers work harder.

But please also also notice that I sometimes stop a set even when you could probably perform another repetition or two. I know some clients think I'm second guessing their strength or tolerance but the truth is I'm just trying to find the sweet spot. If we're emphasizing maximal strength, power, movement quality, or managing overall fatigue, pushing every set to exhaustion may actually work against the goal. Good training isn't about lifting the heaviest weight possible or doing the most repetitions possible.

It's about manipulating how heavy the resistance is and how much fatigue we allow to accumulate based on what we're trying to accomplish.

References

Pareja-Blanco, F., Sánchez-Valdepeñas, J., Cornejo-Daza, P. J., & Rodiles-Guerrero, L. (2026). Optimizing strength and hypertrophy: The combined effect of intensity and velocity loss thresholds in bench press training. Medicine & Science in Sports & Exercise, 58(8), 1773–1781.

Refalo, M. C., Helms, E. R., Trexler, E. T., Hamilton, D. L., & Fyfe, J. J. (2023). Influence of resistance training proximity-to-failure on skeletal muscle hypertrophy: A systematic review with meta-analysis. Sports Medicine, 53(3), 649–665.

Robinson, Z. P., Pelland, J. C., Remmert, J. F., Refalo, M. C., Jukic, I., Steele, J., & Zourdos, M. C. (2024). Exploring the dose-response relationship between estimated resistance training proximity to failure, strength gain, and muscle hypertrophy: A series of meta-regressions. Sports Medicine, 54(9), 2209–2231.

Schoenfeld, B. J., Grgic, J., Ogborn, D., & Krieger, J. W. (2017). Strength and hypertrophy adaptations between low- vs. high-load resistance training: A systematic review and meta-analysis. Journal of Strength and Conditioning Research, 31(12), 3508–3523.