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Time Under Tension: The Scientifically Engineered Set-Timing Technique

Give us a few seconds and we’ll give you stronger and bigger muscles. No, we’re not promising that you can work out for less than a minute. What we are promising is that if you focus on a specific range of seconds, you’ll challenge your muscles in an entirely new way.

You see, while reps, sets and rest time are important variables in your workout, the total amount of time you spend actually doing each set of an exercise can also be critical to reaching your training goals. However, this time component rarely has been taken into account when putting together a weight-training program … until now.

What exactly is it?

Time under tension (TUT) is a way of calculating the total amount of work you place on a muscle. It refers to the total time a muscle resists weight during each set. For example, if you did the barbell curl and it took you two seconds to curl the weight up and another two seconds to lower it, that’s four seconds of tension per rep. Performing 10 reps at this pace would take a total of 40 seconds. Therefore, the TUT for that set is 40 seconds. If you increased the speed of those reps to about three seconds, then it would take you only 30 seconds to complete a 10-rep set. Although the number of reps and the amount of weight are the same, the second set might not increase your muscle mass to the same level as the first. And that’s the basis of TUT training: Focus on sets that last for a certain amount of time based on your training goals. For maximizing strength, the ideal TUT is about 20 seconds or less; for muscle mass, it’s at least 40 seconds; and for muscle endurance, it’s at least 70 seconds.

Don’t abandon set and rep ranges just yet, though you have good reason to focus on them.


Research shows that the best way to gain muscle strength is by performing 1-6 reps per set; for muscle growth, your ideal rep range is 8-12; and for muscle endurance, 15-30 reps prove most beneficial. The problem is that all these ranges assume that each rep takes about four seconds to complete. If you extrapolated those figures, you’d assume that the best TUT ranges are 4-24 seconds for strength, 32-48 seconds for growth and 60-120 seconds for endurance. However, strength coaches and training experts have tweaked those values based on their own experience.

Although no controlled research has been done on the subject, their anecdotal evidence suggests that the best TUT ranges are 4-20 seconds for strength, 40-60 seconds for growth and 70-100 seconds for endurance.

Its About Time

TUT ranges allow you to be more precise about the amount of work you place on a muscle. Using the barbell curl example, if you did 10 reps at four seconds per rep, you worked the muscle for 40 seconds, which coincidentally is the optimal TUT to stress a muscle for gains in mass. But if it took you only three seconds to complete each rep (a TUT equal to 30 seconds), you weren’t training the muscle optimally for growth, even though the reps are in the proper range.

This doesn’t mean you should stop counting reps.

When you’re training for muscle mass, continue to shoot for 8-12 reps. But incorporating TUT training into your routine can allow you to widen that rep range to about 6-15 per set, as long as you stay within the TUT range of 40-60 seconds. So if you decide to perform six reps of barbell curls, you would need to slow down your reps to about seven seconds per rep for a total of 42 seconds of TUT.

If you did 15 reps of barbell curls, you’d need to keep the reps to about 3-4 seconds for a total of 45-60 seconds of TUT.

Eye On The Time

To monitor your rep speed and total TUT for every set, you need to watch the clock. If you train with a partner, have him time you with a stopwatch, help you count off reps at the right speed and keep you in your TUT window. If you train alone, however, timing gets trickier. Try positioning yourself in view of a wall clock or use a watch with a second hand or timer. You can also estimate your time by counting off with the one-one thousand system: Count the time it takes to complete each rep and the set, starting with one-one thousand and counting up.

Variance Is Key

Regardless of your training goals, it’s important to vary your reps and TUT times within the range of your goal so you don’t get stuck in a rut. Make weekly modifications, such as those suggested in the “Countdown to Growth Program” on the previous page. Each week, change the number of reps you perform per set and the time it takes to complete each rep.

If you continue to modify your routine this way, then monitoring your training with the TUT principle can be done indefinitely.

Optimal Rep And TUT Ranges

Author: Jim Stoppani
COPYRIGHT 2010 Weider Publications
COPYRIGHT 2010 Gale Group

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  1. Greg Gabriel says:

    Great article and information! I also sorta suspected this but didn’t quite know the exact numbers or explanation. Been in a few arguments over this concept as well…I knew that reps were always a factor of time.

  2. Daniel says:

    Are the ideas put forward in this article related to constant tension reps where you never lockout?

  3. Lloydius says:

    Great read. Question tho, how much TUT per workout? Or per body part? Is 20sec TUT over 4 sets, 80sec TUT total good for mass or just strength?

    Many thanks

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