New study into slower reps finds slightly better muscle growth

Posted by Dayne Hudson in Muscle Building

Estimated reading time: 5mins

slower reps finds slightly better muscle growth

Slow vs faster reps: which is better?

When we talk about slower reps, we're specifically talking about the eccentric contraction. This is the movement that occurs when we're lowering the weight.

For example, barbell bicep curls: lifting the weight up is a concentric contraction, whilst an eccentric contraction is lowering back down to the starting position.

And this new study we're talking about in this article looked at eccentric contractions in the form of leg extensions. Ten healthy young adults (8 men and 2 women) performed leg extensions with just one leg under the following two conditions:

  • 2 seconds of an eccentric movement
  • 4 seconds of an eccentric movement

And both groups performed the concentric movement, lifting the weight up, for just 1 second to ensure results were consistent.

Each condition did 5 sets at 70 percent of their one-rep max until failure, with 3 minutes of rest in between sets. This program lasted eight weeks.

The researchers measured strength with a 1 rep max test, and muscle growth was measured by an ultrasound, which is very accurate for muscle growth.

So, what did they find?

All muscles of the legs increased!

Okay, so we should just do 2-second eccentric contractions, particularly on the leg extension, and know we're going to get the same amount of gains as taking 4 seconds?

No... hold on a moment!

There was a difference in the vastus medialis, also referred to as the "teardrop" muscle -- which grew larger with the longer eccentric contraction!

And strength? The same.

So, what we might take away from this is that maybe quadricep growth is the same from either 4-second or 2-second eccentric contractions with 1-second concentric contractions. BUT we'll grow slightly larger "teardrops" by practising 4-second eccentric contractions.

And it's a pretty handy bit of information; many people are after maximum tear drop growth.

We might grow bigger “tear drops” from slower eccentric contractions on the leg extension
We might grow bigger “tear drops” from slower eccentric contractions on the leg extension!

How does this align with previous research?

Other studies tell us longer eccentric phases are better than faster eccentrics for quadriceps growth. And there is ample evidence that a great time under tension (which is what we're ultimately talking about here) increases the degree of microdamage.

The researchers of this featured study also point out that they know of only two previous studies that have looked at eccentric contractions and muscle growth:

  • Study 1: 12 resistance-trained men did 3 sets of arm curls at their 8-rep max. They held the eccentric contraction over 4 seconds or 1. They found superior muscle growth with the 4-second concentric contraction compared to the 1. They suggest it's due to a longer time under tension.
  • Study 2: Eight men performed 3 sets of one-legged knee extensions at 30% of their one-repetition maximum. They did either 6-second eccentric contractions or 1-second eccentric contractions. The number of reps was the same. The study found the longer eccentrics induced a greater post-exercise muscle protein synthesis response!

Then there was another study into back squats in untrained men, who performed either 2-second eccentric contractions or 4-second eccentrics.

And they found no difference in muscle growth, but the faster eccentric contraction yielded better strength results.

But is this because of training experience? These subjects were untrained. Also, are upper limbs and lower limbs different?

Well, we need more research. And that's a little snapshot of where we're at.

But it stands to reason that a longer eccentric contraction, and this time under tension, is better for muscle growth. And we'd be wise to incorporate slower eccentric contractions throughout our workout.

4-6 second eccentric contractions should be part of our muscle growth routines.
4-6 second eccentric contractions should be part of our muscle growth routines.

The bottom line on slow vs faster reps 

Slower eccentric contractions, up to 4 seconds, might be better for muscle growth. This is compared to 1-2 seconds of an eccentric contraction. An eccentric contraction is when we're lowering the weight, and not contracting it (lifting it up).

It might be that upper limbs and lower limbs respond differently to longer eccentric contractions and that our training status (experienced or not) plays a role.

Until more research comes to light, longer eccentric contractions, 4-6 seconds, can and should make their way into our gym routines if maximal muscle growth is the goal!


  1. Azevedo PHSM, Oliveira MGD, Schoenfeld BJ. Effect of different eccentric tempos on hypertrophy and strength of the lower limbs. Biol Sport. 2022 Mar;39(2):443-449. doi: 10.5114/biolsport.2022.105335. Epub 2021 Jun 1. PMID: 35309524; PMCID: PMC8919893.
  2. Hackett DA, Davies TB, Orr R, Kuang K, Halaki M. Effect of movement velocity during resistance training on muscle-specific hypertrophy: A systematic review. Eur J Sport Sci. 2018;18(4):473–482.
  3. Bamman MM, Shipp JR, Jiang J, Gower BA, Hunter GR, Goodman A, McLafferty CL, Jr, Urban R. Mechanical load increases muscle IGF-I and androgen receptor mRNA concentrations in humans. Am J Physiol Endocrinol Metab. 2001;280(3):E383–E390.
  4. Pereira PEA, Motoyama YL, Esteves GJ, Quinelato WC, Botter L, Tanaka KH, Azevedo P. Resistance training with slow speed of movement is better for hypertrophy and muscle strength gains than fast speed of movement. Int J Appl Exerc Physiol. 2016;5(2).
  5. Burd NA, Andrews RJ, West DW, Little JP, Cochran AJ, Hector AJ, Cashaback JG, Gibala MJ, Potvin JR, Baker SK. Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men. J Physiol. 2012;590(2):351–362.
  6. Shibata K, Takizawa K, Nosaka K, Mizuno M. Effects of Prolonging Eccentric Phase Duration in Parallel Back-Squat Training to Momentary Failure on Muscle Cross-Sectional Area, Squat One Repetition Maximum, and Performance Tests in University Soccer Players. J Strength Cond Res. 2021;35(3):668–674

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