What is time under tension and how does it apply to training?

Time under stress? Yes, also known as TUT or TBT; I ask you a question… Do you want to know the truth about this topic and understand why some bodybuilding practitioners are using it for their muscle development? Well, here I explain it to you…

Let’s think about this… the standard approach to training in bodybuilding and muscle development has always been to perform each set counting a specific number of reps (for example: 4 sets of 5-7 reps or 4 x 8-12 reps).

Now, lately, there has been more talk of a relatively new approach known as “time under tension”, but if you start to analyze the matter you could be in for a surprise.

Anyway, to better understand this matter, we are going to analyze what is the Time under tension or TBT for short.

What is time under tension?

As its name implies, the time under tension is the total amount of time that the muscle is making an effort throughout an entire series, thus establishing a system where the number of repetitions does not come into play but the time of total effort.

So instead of aiming for, say, 8 reps for a set of as given exercise, you estimate your total “time under tension” at about 50 seconds, for example.

So once the 50 seconds is up, you would interrupt the set, regardless of how many reps you’ve done.

Now, you will hear different guidelines and systems depending on who you talk to or what “generic routine you read on the internet”.

But in general, a TBT of between 1-20 seconds is considered ideal to gain strength, a TBT of between 30-60 seconds is optimal for muscle hypertrophy, and when we have passed 70-100 seconds it would be better for adaptations of endurance. (Again, these are just estimates, you will hear different training guidelines under the TBT system).

Now that you know what it is about, the million-dollar question then is… is time under tension important for muscle growth? Should I stop counting reps and start counting time?

Is it better to count time or repetitions?

My short answer to the above questions is that while the total amount of time your muscles are under tension is important when trying to achieve muscle-building results, it really is not something you need to worry about..

The concept of TBT makes sense, but its real application in training is not well focused, what is more… Who knows for sure what are the optimal intervals for each training objective?

The concept of time under tension tells us something that most of us already know…

  • Very short sets, performed with a low number of repetitions (less than 5) are probably not ideal for muscle hypertrophy, but they are suitable for strength development.
  • Series that have a high number of repetitions (more than 12) are not ideal for hypertrophy either, but they are fine if you are looking to gain resistance.

For this reason, when it comes to maximizing muscle growth, you will almost always be given a recommended range of around 5 to 12 reps per set, and always handling a weight that does not allow you to go beyond that range.

As long as you are training below this range and performing the reps under a quick or explosive concentric movement (when lifting the load) and a well-controlled negative movement (when lowering the load), there is no need to worry about anything other than counting your reps.

If you train in this way, it is more than likely that you are within the recommended TBT ranges for hypertrophy, and even, if you lose or spend a few seconds, keep in mind that these ranges are only estimates and are not confirmed by any concrete research (at least I haven’t found it).

Can tbt training be dangerous?

We already saw that worrying about time under tension is an unnecessary aspect of your training plan, but if you still want to try it, keep in mind that it can have potentially negative effects.

This is because following a stopwatch and performing your sets under an exact time frame is actually a huge distraction, and you’ll end up losing focus on the things that really matter, like rep speed, intensity, and technique.

In addition to this, aiming to optimize time under tension can also cause you to intentionally decrease your repetition rate to ensure you reach the minimum time required.

There is no question that it is important to maintain full weight control at all times, but training theory is pretty straightforward in showing that taking a “super slow” approach to your rep speed is NOT ideal for maximizing muscle hypertrophy.

I said it before, and I repeat it again, the concentric portion of the repetition (or “lifting” phase) should be performed as hard or fast as possible while maintaining the correct technique of the exercise, in turn the eccentric part ( or the “descent” phase) should be done in a controlled way, if all this takes you more than 4 seconds it is probably not effective if your goal is muscle development.

Then time under tension is not important?

Yes, that is important! the total amount of time your muscles are under tension affects how your muscles respond to training.

But simply by keeping your sets within the ” reps for hypertrophy ” range which is around 5-12 reps per set, you would already be automatically landing somewhere within the TUT range (or close to it) for that goal.

And not only that, but you would do it without the unnecessary hassle of having to follow a timer to sync your sets, and without diverting your attention from the things that really matter:

  • Perform the exercise using the proper technique.
  • Use the proper repetition rate that includes a fast concentric phase and a controlled eccentric (but not excessively slow).
  • Train with a sufficient level of intensity by performing approximately 1-2 repetitions less than the concentric muscle failure level in each set.
  • Focus on improving performance from the previous workout either by increasing the amount of weight lifted for a given exercise, or by performing additional reps with the same weight.

If you’re doing these 4 things in every set of your routine, then you’re already going to make incredible gains in the gym and there’s really no need to over-analyze things.

Although “time under tension” is an interesting concept and certainly comes into play in the big picture, it is not something you have to worry about.

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