Is Time Under Tension Important for Muscle Growth?

What is the value of TUT?

Does time spent under tension really matter for muscle growth? Let’s take a deep dive into that topic. The answer is nuanced and more complicated than you might think.

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Time Under Tension: A Deep Diving

Do you think time under tension (TUT), is important for hypertrophy? Or is that mostly bro science? Good question.

Time under tension is the time in seconds between sets. The TUT for 10 reps will be approximately 40 seconds if you use a 3-second eccentric (lowering phase), and a 1-second conectic (lifting phase).

Is it important for muscle growth? Yes and no. I recommend that you do 6-10 reps of each exercise. You should control your eccentric and maintain tension. This is the best way for growth.

A Closer Look at Tut

Time under tension isn’t the primary factor involved in muscle growth; the set duration itself isn’t really important. The physiological response to a specific duration of TUT could play a part.

Did you see that? The TUT itself and the physiological response (lactate and growth factor accumulation during a set lasting 40-60 seconds) are not what I’d call a growth stimulus. They can enhance the adaptive response to the stimulus.

So, what’s the main stimulus for growth? This is how it would look if we used an equation

Hypertrophy stimulus = Muscle fiber recruitment + Mechanical load of these fibers. X number of reps

The amount of force you need to produce your maximum force during a rep will determine how many muscle fibers are recruited. There are several ways to increase this force.

1. Use heavier weights. A heavier weight equals a higher percentage of your maximum.
2. You can’t afford to be tired. Get more reps and/or use supersetsThis decreases the relative maximum of reps to reps because the muscle is tired.
3. Accelerate as fast as possible when lifting weights (force = mass + acceleration). But you’ll see why this is good for strength and power but not optimal for hypertrophy.

Mechanical loading refers putting a mechanical strain on the muscle fibers. To stretch muscle fibers, you need to create as much tension as possible.

Tension is a function of the force that the muscle has to produce. Tension will rise with more force.

Let’s Look at How Muscles Contract, Nerds

Each muscle fiber is made up of myosin filaments and actin. They link together when myosin heads attach to the actin. This is known as a “cross-bridge.”

The myosin head pulls the actin and shortens the muscle. It looks like this.

Reduce the muscle

Now, understand that the more force/tension you need to produce, the more bridges you’ll form.

During the eccentric phase of an exercise, when the muscle’s fibers are lengthening (being stretched), if the bridges remain connected, you create muscle damage and stimulate mTOR activation – two important hypertrophy stimuli.

The bridges can only shorten the muscle fiber; they can’t lengthen it. If the bridges stay connected, muscle tension will be high. When you perform an eccentric movement, the load is lengthening fibers, while the bridges try to reduce them. This is “mechanical stress,” and it’s the main trigger for growth.

That’s why if you have zero control of the weight during the eccentric (very low tension), it’s much less effective for growth. When you don’t actively resist the weight, muscle tension goes down, the number of bridges goes down, and the potential for muscle damage and mTOR activation is lower.

You can maximize the mechanical stress by:

• This is how a muscle contract works: Create as many actin/myosin cross-bridges possible. You can build more bridges if you have more force to produce.
• During the rep, keep tension high. That’s why too much acceleration can decrease mechanical loading. Too much momentum can cause a decrease in the strength of the muscles to lift the weight. This causes fewer bridges to be formed.
• While the tension is high, lengthen/stretch fibers. A lower level of tension results in fewer actin/myosin cross-bridges and therefore less stimulation for hypertrophy. That’s why it’s more effective to do the eccentric under control, not fast. The stretching of the fibers, while they’re producing tension, is responsible for muscle damage and mTOR activation.
• You should recruit as many fibers possible, make a lot of bridges with those fibers, lengthen the fibers and form as many bridges you can. Do that over several reps. That’s it!

Okay, so what about Tut?

It is more important to do as many reps as possible than to keep your tension under control. Each rep is a new round of mechanical stress. This happens through a load-lengthening and a new loading of muscle fibers.

Two scenarios are offered to illustrate my point.

1. 10 reps at 225 pounds with a 2010 pace (2 seconds to lower, no rest at the bottom, 1 second for the lift, and no rest at the top). That’s a TUT of 30 seconds because each rep took 2 seconds to lower.
2. 5 reps at 225 lbs and a 5010 pace. That’s still a TUT of 30 seconds because each rep took 5 seconds to lower, but you did fewer total reps.

Even though the TUT and load are equal, scenario A is better.

Why? Why? Because muscle damage and activation are affected by how many times you stretch a muscle fibre in a set. It’s like this: Every time you stretch a fiber under load you are triggering growth.

Now, if you add a third scenario where you’re doing 10 reps with a 5010 tempo (a TUT of 60 seconds), would it be more effective? Nope! To do that, you’d have to use significantly less weight, probably something like 185-195 pounds instead of 225 pounds. A lower weight will result in less muscle tension, which would make each rep less effective.

Caveat: The longer you are under tension, the better. This can help increase muscle growth. When you reach the 40-60 second range, if the intensity is high enough so that you reach failure in that time zone, you’ll be producing a lot of lactate and growth factors, which can help with the adaptation to training.

The following three scenarios would be effective in order of effectiveness:

• 10 reps at 220 pounds using a 2010 tempo
• 10 reps at the 195-pound weight with a 5010 tempo
• 5 reps at 220 pounds with a 5010 pace

This will reduce mTOR and muscle damage by completely decreasing tension while lifting explosively. This would be great! strength and power, but not great to hypertrophy.

The new order would be:

• 10 reps at 220 pounds using a 2010 tempo
• 10 reps at the 195-pound weight with a 5010 tempo
• 5 reps @ 225 pounds, with a 2010 pace

Is Tut Important?

TUT will not be the main stimulus for growth. TUT will not be the main growth stimulus. It only leads to some physiological reactions, such as lactate and growth factor, which can play a limited role in hypertrophy.

Local growth factors can stimulate protein synthesis somewhat (which speeds muscle tissue repair, building, and rebuilding), while lactate may increase follistatin levels, which can reduce myostatin slightly.

A lower level of myostatin can lead to more muscle building. But don’t jump on the lactate bandwagon just yet – it likely won’t make a huge difference.

I do like to shoot for longer TUT on exercises that won’t cause much muscle damage. Think isolation work mainly, especially if the eccentric isn’t loaded for the whole range, like lateral raises and barbell curls. This approach is ideal for people with more difficult muscle repair, such as seniors or those who are under a lot of stress.

These cases can be helped by shooting for a time-to-take of 40-60 seconds while maintaining a moderate body weight.

I do use slow eccentrics a lot. I’m not being contradictory: I use them for reasons other than stimulating maximum growth, like improving motor learning, strengthening tendons, and becoming stronger eccentrically.

Thank you Coach! You might also consider the argument that a 90-second TUT sets of high intensity engages and fatigues all three types of muscle fibers (IIA, IIB).

This must have some benefits (as I’m a living proof that the method works).

From a type I perspective they might. But they don’t have much growth potential.

Keep in mind that I’m NOT saying that longer sets are not effective. I’m saying that the time/duration factor is not the direct cause

And about engaging all the muscle fibers, that’s not really how it works. A shorter set (e.g. A set of 6-8 reps, taken to failure or very close to it, will engage all muscle fibers and fatigue them enough to grow. A set, regardless of its duration (except if it is done via rest/pause), will give you 5-6 effective reps. “work” To stimulate growth

A set that lasts 90 seconds must be performed with a lighter load, unless you are using rest/pause. This means that the early part of the set won’t be as efficient at growing hairs. Only the last few reps will be effective if you need to recruit fast-twitch fibers.

It can help you achieve your goals. “illusion” of being more effective because of the massive pump and burn, but it really isn’t.

You say there must be benefits and you claim that you are the living proof it works.

Here are two things:

1. I’m not saying that it doesn’t work. I’m saying that it won’t work better than lower reps
2. Do you believe this is the only method that you are using? Is it the ONLY method you are using? “working”. Try doing only this method for 6-8 weeks to really assess if it’s worth it

Are there any advantages? It depends on what you’re looking for. This article is focused on hypertrophy and time sub tension. In that case, no, it doesn’t have benefits over other ranges.

It can also be used to improve performance, such as improving tolerance to lactate and improving blood flow to muscles through the development of capillaries.

It can also help develop mental fortitude which is a highly desirable trait.

Recognize your commitment and experience.

The second question was about the 90-second TUT sets. I have been using various Darden techniques over 1.5 years (this was in 2019-202). I saw significant strength and hypertrophy gains in those years, which I kept in a personal training log. I also presented (bioimpedance scale), as an early thread on the Darden forum. My bodyweight rose from around 180 to 200 pounds with an exercise program. “estimated” bodyfat kept around 14%). Truth be told, I was at a similar weight 25-years ago – so it could have been a case. “regained” If applicable, muscle

Between 2007 and 2015, I attended several group training classes, many days per week. While I didn’t gain much weight, I was able to maintain a healthy 180-pound weight. Between 2015-2018, my training was less frequent as I had two daughters and became a father. After that, there was a short period of crossfit and group training for 6 months.

Ok, I should probably also mention that I did Fortitude Training for six months in 2021. This increased my body’s strength and weight to 214 pounds (with a 15-16% bodyfat estimate). After that I did Zone Training for a couple of months, losing some weight though preserved strength – before re-entering Darden regimes for a couple of months (preservation/maintenance).

The Schoenfeld Max Muscle Plan 2.0 was my next discovery. It gave me additional strength and helped me regain some weight. “strength phase”. My third baby girl was born in June. This brought an abrupt halt to my training.

My current and most rewarding combination was Powerlifting with Darden regimens. They appear to be a perfect match, each adding something to the other. Current body weight is currently 214 pounds. A visually more elegant bodyfat estimate (13%)? It is possible to guess.).

Two days per week of full-body training have been my standard since 2020. It is a great solution, and it works very well considering that I am 48 years old.

What do you mean? Let’s find out more.

Two days of training per week currently:

Day 1 (Monday), Full body, 8-12 sets, featuring either or both a combination of 4/4 cadence (30-10-30, 30-30-30), 10-60 sec negatives to chins and dips, and 30-30-30 (30). Occasional cluster sets or high-rep strategies, as well as zone training and other Brian Johnston strategies. Machine-based workout. OR at home with Synapse CCR pulley systems or resistance bands. My free-form day, where experimentation and imagination make training fun! You can go crazy with HIT is the WOD! LOL

Day 2 (Thursday): Powerlifting together with a partner. Barbell squats 5×3-5, barbell bench press 5×3-5 and barbell deadlifts 5×3-5. In a three week cycle, alternate between 3,4 and 5 reps each day. Concentrate on explosive intent and controlled negatives. Raise your weight to the fixed/same work weight for all sets. The 3 rep day allows you to increase your weight in order for the following weeks of 4 or 5 reps. If you can complete 5×5 reps on a weight, I consider it safe and secure. Slow double progression.

TUT was never a causal concept to me. The TUT correlation with volume and rep speed is not surprising. “TUT” It has no inherent quality. Some of the most popular exercises “TUT”Cable crossovers are one example of the worst builders. However, some (most) are better. “basic” Exercises like deadlifts have a short TUT. Isometrics are TUT and not the key to physical greatness (apart from Charles Atlas/Bob Hoffman, and the US Olympic team of the 60s that started on Dbol lol).

I’ve been thinking about TUT in the context of “effective reps” lately and wondering if a training session’s total TUT in the effective-reps zone could be a driver of hypertrophy, since many people seem to get great results from training with various rest-pause methods like myo-reps, where volume is added specifically in that “effective reps” Zone of the last five reps before concentric fail. I’ve been using this method lately since working a lot of hours and having very young children I have very little time to train but what little training I actually do my muscle-memory is coming back in a big way, bigger and faster than it ever has before when coming back to training. How does adding volume only in the effective reps area relate to this article?

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It is not surprising that your conclusions are wrong. Thank you for the information.

Numerous studies have demonstrated that a wide range of loads and reps (set durations), are equally effective in increasing strength and hypertrophy. The speed and number of repetitions make no difference when the duration is the exact same.

Any method of strength training done hard, progressively, and consistently, with a volume and frequency that doesn’t exceed what an individual can recover from and adapt to, can eventually get them as strong and muscular as their genetics allow. It is easier to move slowly and lift heavier loads for longer sets. It is just as effective in enhancing strength and hypertrophy over the long-term. Although it may seem like it is moving faster when there are heavier loads and smaller sets, it actually isn’t. SaferFor long-term performance and safety, efficacy is equally important.

Hi Coach. I have tendons that are quite damaged. I tend to use a slow tempo, and have used TUT as an exercise technique to strengthen my tendons. Do you think TUT has value for tendon health/strengthening? You might consider tendon strengthening as a topic in a future article. Many thanks

You’re shitting on his conclusion (built by years of experience and training 100s if not 1000s of people and witnessing their growth patterns) while providing zero sources for your claims. Bravo, sir, I admire your boldness.

There isn’t a single advice I’ve taken from Chris that hasn’t paid back in dividends. I’ll continue to take his word over disk jockeys.

But not by itself. Meaning that it’s not the fact that a set lasts XYZ seconds that promotes tendon development.

Loaded stretching and slow eccentrics can also cause tendon growth. Two methods that will typically use longer TUT, but it’s not the TUT itself that has the effect, but the nature of the method/tension.

Chris,

Great article as usual. Some of the protests are a mystery to me. Question: I tend to follow Seedman’s eccentric isometric protocols and these so seem to show many of the benefits you refer to. Although I listened to the squat podcast with Seedman, I’d be interested to hear your thoughts on the whole.

Thanks Coach for the great information! You write about the activation of mTor… What can you say about the benefits of mTor activation by a natural bodybuilder after 40 years (often there are articles about the connection between mtor and cancer…) Thanks

There is more than one mTOR. Exercise (very short duration) triggers protein synthesis. Insulin and overreating activate mTORs but they are not the same thing.

The latter can lead to faster aging or the growth of cancerous cell (if you already have them) especially if it is chronically high (as in the case with simple carbs), but not the temporary one that occurs when you lift weights.

This is a gross oversimplification. There are several types of mTOR as well a various tissues affected, but that’s the gist of it.

Training is not going to cause cancer/aging problems. Bulking is what is causing the maximum muscle building.

What is mTOR?

Rapamycin’s Mechanistic Target. It’s extremely complex so let’s just say that it is an enzyme that activates cellular development. It stimulates protein synthesis, repair, and growth when activated by mechanical tension from the muscle fibers.

Coach, thank you for your response! Coach, I also have a question regarding TUT. How long do you need to rest between sets if they last for 40 to 60 seconds? And how many sets should you do per muscle group if you are a natural lifter. If I understood correctly, then glycolysis is active in the muscles during this TUT interval. This helps to ensure that their work is done properly. The first 20 seconds of the set, the muscles work on creatine phosphate, and already from 20 to 60, glycolysis is actively proceeding, the by-product of which is the accumulation of lactate in the muscles, therefore, so that the second set was also productive you need to enough rest, it is also possible to do another exercise (superset)…Thanks

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