Why Training Intensity Matters More Than Volume for Muscle Growth

When it comes to building muscle, many gym-goers focus on training volume—how many sets and reps they complete each week. While volume has its place, training intensity is the real key to making progress. If your sets aren’t challenging enough, all the volume in the world won’t help you build muscle effectively.

In this blog, I’ll break down why intensity is more important than volume, how to measure your intensity, and simple ways to push yourself harder in the gym.

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What Is Training Intensity?

Training intensity refers to how hard you’re pushing yourself in each set. It’s about getting close to failure—where you physically couldn’t complete another rep with good form.

For beginners, simply lifting weights is often enough to stimulate muscle growth and you’re likely to see great improvements in the first 12 months. But as you gain experience, your body adapts and require a greater stimulus to ensure that you continue to make positive steps forward in both size and performance.

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Why Is Intensity More Important Than Volume?

1. More Volume Doesn’t Always Mean More Muscle

Many people believe that doing lots of sets automatically leads to bigger muscles. While research shows that volume plays a role, it only works if those sets are actually challenging. If you’re doing 15 sets per muscle group per week but never pushing yourself close to failure, you’re not making the most of your time in the gym.

2. You Can Build Muscle with Fewer Sets—If the Intensity Is Right

Some people can get great results with as little as two sets per exercise—as long as both sets are properly challenging. This method is called the ‘Double progression model’ but that’s something i’ll discuss in another blog later down the line.

The premise though is to be training without enough stimulus - most often weight - using good form and the right level of effort.If you’re simply going through the motions, lifting the same weights for the same reps week on week for a long time, you’re likely to plateau and hinder your progress.

3. Your Muscles Need a Reason to Grow

Muscle growth happens when your body recognises that it needs to adapt to handle more stress. If you never push your muscles to their limits, your body has no reason to adapt and build new muscle tissue to deal with the demands.

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How Do You Know If You’re Training Hard Enough?

The simplest way to measure intensity is by asking yourself this question after your final set:

“Could I do another set with the same reps and weight?”

• If the answer is yes, your intensity is probably too low.
• If the answer is no, and you feel like you’ve really worked hard, you’re on the right track.

A good rule of thumb is to finish most of your working sets with just 1-2 reps left in the tank. If you could do 5 or more extra reps, then your rep target then its time to increase the intensity.

A study in 2021 found that only 22% of people (out of 160) actually selected the correct weight that they could lift for 10 reps, with 33% actually achieving 13-15 reps showing that people often undershoot how much weight to use. 

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How to Increase Training Intensity

There’s a few approaches to increase the intensity of your sessions other than just adding more sets.

1. Add More Weight

One of the easiest ways to make your sets harder is to increase the weight. If you can complete all your reps easily, try adding 2.5–5kg more next time.

2. Slow Down Your Tempo

Tempo refers to how fast you lift and lower the weight. Slowing down the movement (especially the lowering phase  - a.k.a the eccentric phase) increases time under tension, which forces your muscles to work harder. Try lowering the weight for 3–4 seconds before pressing it back up. Be aware that this style of training can elicit high level of DOMS (Delayed Onset Muscle Soreness) though so bear that in mind!

3. Reduce Rest Time

If you’re taking long breaks between sets, you might not be pushing yourself as hard as you could. Try cutting your rest periods down—for example, from 90 seconds to 60 seconds—to keep the intensity high.

4. Use Drop Sets or Rest-Pause Training

• Drop sets: Once you finish a set, immediately reduce the weight and keep going until failure.
• Rest-pause training: After hitting failure, take a short 10-15 second break and then try to squeeze out a few more reps.

These methods help you push past your usual limits and force your muscles to work harder than they’re used to.

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When to Push Harder (and When to Pull Back)

It’s important to push yourself, but also to listen to your body. Some days, you’ll feel strong and should aim to lift heavier or do an extra rep. Other days, you might feel fatigued, and that’s okay—you don’t need to max out every session. Some days, you will be training to hit the bare minimum and get in and out the gym quickly.

However, if you constantly feel like your workouts are too easy, it’s a sign you need to step up the intensity.

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Final Thoughts: Are You Training Hard Enough?

If your muscle growth has stalled, don’t automatically assume you need more sets. Instead, take a look at your intensity. Ask yourself:

• Are you truly pushing yourself in each set?
• Could you add weight, slow down your reps, or shorten your rest times?
• Are you finishing your final sets feeling like you could do more?

By focusing on intensity rather than just volume, you’ll get better results in less time—without spending hours in the gym.

Try applying these tips to your next session, and let me know how it goes!

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About Me & How I Can Help

I’m Sam, a personal trainer dedicated to helping people train smarter, not just harder. Whether you’re a beginner looking to get started or someone who wants to break through a plateau, I can help you build muscle, gain confidence, and train more effectively.

I offer personal training services from my private facility in Stourbridge, and also support clients online with personalised training plans.

If you’re looking to improve your workouts and see real results, get in touch today! Let’s work together to create a training plan that actually works for you.

Got questions? Drop me a message—I’d love to help!