Time Under Tension vs Reps

time under tension

Time under tension training is a great bodybuilding principle.

But today we’ll look at time under tension vs reps – as in straightforward sets and reps training – for muscle growth.

Because a recent study published in the Journal of Physiology suggested that time under tension is more effective for building lean muscle tissue than regular weight training – even when using the exact same weight.

This led to several media outlets reporting that we should immediately ditch standard weight training and repopulate our training routine with sets based around TUT training.

So today we’ll look at this study and see just what all the fuss is about, and what the differences in muscle growth actually were.

time under tension

What Is Time Under Tension Training?

This has long been one of my favourite training methods.

It has long been one of my favorite methods for shocking the body, and you’ll find it in many of my free training programs.

For those who may be unfamiliar with this training principle, here’s a quick breakdown of the differences between TUT training and straightforward sets and reps:

“Instead of focusing on a designated number of reps per set, time under tension sets focus on working for a target number of seconds per rep. The goal is to keep forcing out these slower repetitions until you reach the overall target per set.”

And let me tell you – few things can contend with the feeling of overall defeat than your quadriceps burning like rubber, only to look at the clock and see another twenty seconds remaining, each second booming as they tick down in what appears to be slow fucking motion.

But is it really true that TUT is superior to regular weight training when it comes to building cold, lean muscle tissue?

time under tension

Time Under Tension vs Reps – What Does Science Say?

Researchers from McMaster University, Canada, analyzed whether the length of time a muscle was placed under tension would produce a bigger anabolic response than simply training to a set number of repetitions. (1)

They had two groups of subjects following different training protocols with their leg workout.

Both groups performed 3 sets of leg extensions using the following instructions:

  • Group A used 30% of their one rep max and performed 12 second reps
  • Group B used 30% of their one rep max and performed 2 second reps

Both groups performed the exact same number of reps.

The group who used the TUT protocol noticed a significant increase in muscle protein synthesis (muscle building).

In fact, MPS was elevated by 114% in the TUT group, compared to 77% in the controlled group.

So this study appears to show us that time under tension is more important than the amount of weight lifted.

time under tension vs reps

The Real Hero

But here’s the thing..

It might be tempting to read this paper at face value and presume that time under tension training is the new holy grail, and that decades of bodybuilding training are now outdated advice.

In fact, many news outlets did just that.

But when we dig a little deeper, we see why these differences were so notable.

The real “hero” responsible for increased muscle protein synthesis (muscle building) here is not time under tension, it’s muscle failure.

If you  train with my online workout programs or have read my article on high reps vs low reps you will already know that I’m a massive fan of training to failure.

That’s because several key studies show that an increased lactic acid output during exercise also leads to increased metabolic stress and growth hormone. (2, 3)

And when it comes to building fresh lean muscle, that’s certainly a good thing!

In the study above, Group A (our time under tension) group were able to get far closer to muscle failure than Group B.

While Group B used a weight only 30% of their one rep max for the set, our TUT group made the most of that lighter weight by holding each repetition for an additional 10 seconds.

It’s common sense to see that performing a set with 30% of your one rep max while doing 12 second reps would create much more of a “burn” than only 2 second repetitions, and that is the real secret to the TUT group’s superior results.

Time Under Tension is a great principle to utilize from time-to-time in order to shock the body. Most of my clients use it.

But in order to truly compare the effects of time under tension vs reps for muscle growth, we’d need to see both groups using a weight which allowed them to reach muscle failure.

Indeed, he main take-home point from this study is the fact that if you want to force new results from your muscles you need to be taking them to failure.

tut results

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1. Burd, N.A., et al. “Muscle Time Under Tension During Resistance Exercise Stimulates Differential Muscle Protein Sub-Fractional Synthetic Responses In Men.” J Physiol. 2012 Jan 15;590(Pt 2):351-62.
2. Burd, N. A., et al. “Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise In Young Men”. PLoS ONE 5(8): e12033, 2010.
3. Burd, N. A., et al. “Enhanced Amino Acid Sensitivity Of Myofibrillar Protein Synthesis Persists For Up To 24 h After Resistance Exercise In Young Men”. J Nutr. 2011 Apr 1;141(4):568-73.

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