Time Under Tension, Rep Speed/Tempo and Eccentric vs Concentric

Two topics I purposely left out of my guide to creating The Ultimate Weight Training Workout Routine are time under tension and rep tempo. Why? Mostly because I didn’t feel they were important enough to include. Plus, I just didn’t think people would actually care about them.

I still think I’m right about that first part, but boy was I wrong about the second. Seriously. I’ve probably had someone ask me about these two subjects every single day since then, and I keep responding with the same ‘copy and pasted’ answer along with a promise to eventually write an article about it.

Today it’s time to finally make good on that promise.

Let’s first begin with the basics to make sure we’re all on the same page…

The Anatomy Of A Rep

The following is going to be pretty noob-ish stuff that most people already know, but since I know I’ll be referring a bunch of noobs to this page in the future, I can’t leave it out.

So, let’s break down the 4 steps of a typical rep of a typical set of a typical exercise:

1. The starting position. This is where the weight is when you begin a rep of an exercise. For example, with a barbell biceps curl, this is the point when your arms are down at your sides and the barbell is down in front of your upper thighs.
2. The ending position. This is where the weight is when you finish a rep of an exercise. For example, with a barbell biceps curl, this is the point when your elbows and biceps are flexed and the barbell is up in front of your chest.
3. The concentric portion of the movement. This is the “lifting” or “positive” portion of a rep, when you are moving the weight from the starting position to the end position (against the resistance). With a barbell biceps curl, this is when you actually do the “curl” and flex your elbows/biceps to move the weight up towards your chest.
4. The eccentric portion of the movement. This is the “lowering” or “negative” portion of a rep, when the weight is moving from the end position back to the starting position (with the resistance). With a barbell biceps curl, this is when you are extending your elbows and the barbell is being lowered back down towards your thighs.

And that brings us to two related topics involving exactly how these 4 steps should go…

Rep Tempo/Speed and Time Under Tension

• Rep tempo (sometimes called “rep speed”) refers to the tempo (or speed) at which you perform a rep of an exercise. For example, 2 second concentric, 1 second pause at the top, 3 second eccentric, 1 second pause at the bottom (this is just one completely random example, by the way).
• Time under tension (aka TUT) refers to how long each set lasts, or really the total amount of “time” your target muscles are “under tension” during a set of an exercise. For example, you might see something along the lines of 1-20 seconds being ideal for strength, 20-60 seconds being ideal for muscle growth, and 60+ seconds being ideal for muscular endurance.

Time under tension can generally be increased or decreased two ways. The first is by simply doing more or less reps in a set. So, a set of 10 reps will (typically) lead to more time under tension than a set of 5 reps on a given exercise.

The second way is by adjusting the rep speed. If you perform that set of 5 reps with a slower tempo and/or the set of 10 reps with a faster tempo, the set with fewer reps can become capable of providing a larger time under tension than the set with more reps.

How Important Is Time Under Tension?

I think the idea of TUT is an important aspect of your training, especially when the goal is muscle growth. Because, after all, you do want your muscles to be under a certain amount of tension.

But at the same time, I don’t actually think you need to give a crap about it.

Not even half a crap, in fact.

What I mean is, if you’re exclusively doing a bunch of REALLY short sets, I don’t think you’ll be training optimally for muscle growth. Similarly, if you’re exclusively doing a bunch of REALLY long sets, I also don’t think you’ll be training optimally for muscle growth.

But, you know this already. It’s why exclusively doing really low reps (like 1-5) or really high reps (like 15+) wouldn’t be ideal for muscle growth either. And it wouldn’t. The first would be more ideal for strength, and the second would be more ideal for endurance.

This of course is why I recommend 5-15 as the ideal rep range for muscle growth, along with a rep tempo that is neither too slow nor too fast (more on that in a second).

Which is all just my way of saying that you don’t need to focus at all on how long your sets are taking. No need to set a watch. No need to count in your head. No need to purposely make your sets last a specific number of seconds.

What you should focus on is making sure your overall workout program is designed intelligently for your goal (optimal volume, frequency, intensity/rep ranges, exercise selection, etc.), that you’re using good form/properly training the target muscle group(s), and that you’re creating progressive overload.

That’s the stuff that matters.

And as long as you’re doing that stuff right, guess what? Your time under tension will automatically end up being whatever the hell it should be and the rest will take care of itself.

How Important Is Rep Tempo/Speed?

I’d say it’s important, but not enough to turn it into a mess of over-complicated specifics.

Let me explain.

I definitely think there is a right way and a wrong way to perform each rep of each exercise. There is a “good” general speed and tempo, and then there’s the opposite of that which I think can best be described as either stupidly fast and stupidly slow.

And as long as you’re avoiding those stupidly fast/stupidly slow extremes and fall somewhere in the middle, you’re probably doing your reps just fine.

Simple as that.

So while rep tempo can certainly have its uses, I honestly don’t put much emphasis on it and almost never use or prescribe a specific number of seconds for the concentric or eccentric portion of a rep. I find it’s more of a distraction than anything else. I’d much rather see 100% of the focus during a set be on proper form, using the target muscle(s), and progression… not counting seconds.

That doesn’t mean I don’t have a slightly more specific recommendation for you, though.

Here’s What I Recommend

For most of the people, most of the time, I like to see the weight lowered under control on the way down, and then exploded back up.

Allow me to break that down…

The Eccentric

Regardless of the exercise being done, you should lower the weight in a slow, smooth and controlled fashion. Definitely NOT super slow (that’s a whole other idiotic training method for another day). Just slow enough so that you and the target muscles are fully in control of the weight rather than just gravity alone.

This would mean that the weight is NOT just dropping and you’re NOT just letting it fall and lower on its own. You’re controlling it the whole way down.

The Concentric

As for the lifting portion, this can vary depending on the exercise being done.

In most cases however (especially most compound exercises), you should explode the weight. Or, as I sometimes like to describe it… hit your reps with a purpose.

Meaning, don’t intentionally slow down the speed of this part of the rep. Try to move it from the starting position to the end position in a quick and explosive manner. This DOES NOT mean throw the weight, or bounce the weight, or swing the weight, or use momentum to get the weight where it needs to go.

It just means, in a controlled fashion where proper form always remains intact and nothing funny/stupid makes an appearance, you should move the weight from point A to point B in a powerful, forceful, swift motion. Hit that rep with a purpose.

Are There Exceptions?

Yes, some exceptions to these recommendations do exist.

For example, calves tend to benefit from a slower eccentric and a pause at the bottom. And certain exercises are just less suited for being “exploded” (e.g. isolation exercises where the focus should be more on contracting/feeling/fatiguing the muscle rather than maximal strength output and progression). Plus, certain goals warrant doing certain things (such as speed benching).

But for the most part… controlled eccentric, explosive concentric is what I recommend.

No need to make it any more complicated than that.