Skip to main content

Should you speed through reps or slow down for muscle growth? Study explores

New research suggests maybe we've been overthinking the timing of our reps

By Steph Green Published November 21, 2025

man lifting weights in the gym overhead press — Ivan / Pexels

Should you really slow down your reps in the gym for muscle growth? Does it really matter how long each rep lasts? You might have heard gym buffs and bodybuilders talking about slowing down those reps and focusing on control and technique rather than speed. From time under tension (TUT) to tempo and eccentric training, these are frequent hot topics in the world of bodybuilding and fitness.

In an interesting study, researchers explored how tempo affects hypertrophy (muscle growth), and it turns out it doesn’t matter as much as we thought. Let’s check out the research.

The study

In a meta-analysis published in the Journal of Strength and Conditioning Research, researchers examined 14 high-quality studies to assess how the concentric and eccentric phases of an exercise affected muscle growth and how muscles responded to time-under-tension. Does lifting weights slowly or quickly build more muscle? In these 14 studies, the only factor that changed was the speed of the repetitions, but the weight, sets, rest, and everything else stayed the same.

The study authors compared:

Slower reps: Averaged around 3.5 seconds per rep. (Ranging between 1.7 and 4.5 seconds).
Faster reps: Averaged around 1 second per rep. (Ranging between 0.3 and 2 seconds).

The results

Here are the results:

Slow and fast reps both yielded the same amount of muscle, with no meaningful difference in muscle growth between the two.
The speed of your reps doesn’t have a major influence on muscle growth.

Recommended Videos

The study authors also assessed differences between eccentric-only, concentric-only, upper vs. lower body, and training to failure vs. not training to failure. The results showed that the differences in muscle growth among these were tiny or uncertain. Overall, research shows that concentric-only training isn’t as favorable for promoting muscle growth compared to concentric-eccentric training.

Concluding thoughts

The researchers concluded that you don’t need to rush or really slow down when weightlifting to build muscle because it makes a minimal difference, at least according to this meta-analysis. It’s better to focus on training consistently, training close to fatigue, incorporating progressive overload, and using the right weight. It’s also best to make sure you’re powering through enough sets per muscle group.

Maybe sometimes we’re overthinking it in the gym. Instead of focusing so much on the speed of your reps, the researchers concluded that it’s better to shift your focus to efficiency and safety. Go with what feels right and more comfortable for you, for safety, efficiency, and technique, rather than worrying so much about the exact number of seconds you’re holding each rep.

Steph Green (Steph Zee) is a singer-songwriter and professional writer with over 12 years of experience in healthcare and…

Topics

Workouts

Health & Fitness

From wheelchair to walking: The power of mindset, movement, and never giving up

Sometimes it's the hardest roads that lead us to a deeper sense of purpose

Steph Zee Christmas Secret Music Video Steph Green

I never expected I'd have to learn how to walk again. That journey took me from writing for doctors and magazines to spending thousands of hours researching health and autoimmune disease. When we have excellent health, many of us don’t give it much thought until those sneaky symptoms start to show, and one day it all comes crashing down. Now, our health becomes one of the most important priorities. When we feel good, we can be more productive and chase our dreams. When our health declines and we don’t feel so good, one of our biggest dreams is just to feel better.

I became a health writer 12 years ago, shortly after graduating with my creative writing degree and getting a diagnosis of the autoimmune bone condition, ankylosing spondylitis. In an effort to improve my health, stay mobile, and help prevent my bones from calcifying and fusing, I spent thousands of hours studying everything from nutrition and naturopathy to conventional medicine and holistic healing. I heard this somewhere, so I can’t take credit, but I like to say I went to “save my ass university”, because pain and illness are some of the biggest motivators.

Health & Fitness

I tried Magic Mind for a month and here is what happened to my productivity

Does Magic Mind really help with your productivity or is it just another buzz.

Furniture, Business Card, Paper

I am proudly an all-brown beverage man. I say it often: I am coffee in the morning, bourbon in the evening, and Pepsi/Coke in between. I know what you're thinking: What about water? Well, all of those are mostly water. And who wants to drink the same thing they bathe in? That sounds gross. All jokes aside, the coffee addiction is real, and I am not alone. Who thinks they can truly conquer a day without a hard shot of caffeine? I would get it in an IV if it were feasible to do on the subway instead of a cup to go. But that doesn't have to be the only way you develop your productivity. Instead, you can look to the more natural and healthy methods to maintain and increase your effectiveness. I got my hands on some Magic Mind recently, one of the many different products that claim to elevate brain health, increase mental performance, and, of course, replace the coffee without losing the energy boost. But does it work?

The scientific hoolah

Health & Fitness

NOBULL debuts new colorways for daily running shoe, Journey 2

Four new colorways just dropped for NOBULL's best-selling Journey 2 sneaker

NOBULL

NOBULL's Journey 2 sneaker is one of my favorite go-to sneakers for the gym (and my husband's, too). There's really something to be said about a sneaker that adds comfort, style, and durability to your gym outfit. I've been wearing these weekly for awhile now -- but now NOBULL has dropped even more fun colors in the same comfortable show. Just in time for the summer, NOBULL just dropped four new colorways in the Journey 2, including Classic White Cayenne, Classic White Signal Pink, Lunar Mineral White, and Blue Haze. These fun, vibrant colors add a touch of color to every gym outfit.

With a plate-less design, Journey 2 delivers a naturally smooth, cushioned ride. A multi-surface outsole provides reliable grip across varied terrain, while NOBULL’s unique stability chassis keeps your foot locked in through every stride and transition, so you can move freely wherever the miles take you. While I'm not usually one to make a statement with my athletic footwear, I have to admit I'm pretty excited about the drop of these new colors. The four new colors join the line up that still includes the classic colors, such as Classic White, Jet Black, and Molten.