Welcome to the forums.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. Come join us in on one of the best online fitness communities. We have 16,000 members that are likeminded towards a fitness, bodybuilding lifestyle. Registration is free and only takes but a few minutes. By joining our free community you will have access to communicate privately with other members (PM), respond to polls, upload content and access many other special features. You will be able to create threads to discuss and or create a fitness regimen. Or just bounce ideas off of some very knowledgeable members. So don't miss out. Registration is fast, simple and absolutely free so please, join our community today!

Register FAQ Members List Calendar Arcade Mark Forums Read
Go Back > Bodybuilding and Fitness Discussion > Training
User Name

Thread Tools Display Modes
Old 03-04-2023, 06:01 AM   #1
liftsiron's Avatar

Join Date: Nov 2003
Location: Cimmeria
Posts: 18,696
liftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud ofliftsiron has much to be proud of
The Truth About Time Under Tension

The Truth About Time Under Tension
Coaching Lab & Plans
Christian Thibaudeau Coaching
Elite Coach
Jan 26

Does TUT Really Matter?

Is time under tension really important for muscle growth? Letís take a deep dive into that topic. The answer is more nuanced than you think.

Time Under Tension: A Deep Dive

Does time under tension (TUT) matter for hypertrophy, or is that mostly bro-science? Good question.

As a refresher, time under tension refers to the duration in seconds of a set. If you do 10 reps with a 3-second eccentric (lowering phase) and a 1-second concentric (lifting phase), the TUT will be roughly 40 seconds.

Now, does it matter for muscle growth? Yes and no. My recommendation (for most people on most exercises) is to just try to get gradually stronger for sets of 6-10 reps while controlling the eccentric and maintaining tension. This is the best way to stimulate growth.
A Closer Look at Tut

Time under tension isnít the primary factor involved in muscle growth; the set duration itself isnít really important. But the physiological response to a certain duration of TUT may play a role.

Did you get that? The TUT itself and the physiological response (lactate and growth factor accumulation during a set lasting 40-60 seconds) are not what Iíd call a growth stimulus. But they can increase the adaptation from the stimulus.

So, whatís the main stimulus for growth? If we were to use an equation, it would look something like this:

(Muscle fiber recruitment + Mechanical loading of these fibers) X number of reps = hypertrophy stimulus

The number of muscle fibers you recruit is dependent on the amount of force required relative to your maximum force production potential during a rep. You can increase the amount of force required relative to your maximum a few different ways:

Use heavier weights. Heavier weights = greater percentage of your maximum.
Create fatigue. Do more reps or use supersets 92, which decreases your relative maximum from rep to rep because the muscle is tired.
Accelerate as much as possible when lifting the weight (force = mass x acceleration). But youíll see why this is good for strength and power but not optimal for hypertrophy.

Mechanical loading refers to imposing a mechanical stress on the muscle fibers. That means you must create as much muscle tension as possible to stretch the muscle fibers while tension is still there.

Tension is related to the amount of force the muscle needs to produce. The more force required, the higher the tension will be.
Letís Look at How Muscles Contract, Nerds

Each muscle fiber has actin and myosin filaments. They connect with each other when the myosin heads hook themselves to the actin. This is called a ďcross-bridge.Ē

Then, the myosin heads pull the actin, shortening the muscle. It looks like this:

Actin Filament
Actin Filament1240◊698 105 KB

Actin Myosin Bridge
Actin Myosin Bridge1240◊698 109 KB

Shortening the Muscle

Shortening the Muscle
Shortening the Muscle1240◊698 111 KB

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

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

Concentric Action
Concentric Action1240◊698 130 KB

Eccentric Action
Eccentric Action1240◊698 124 KB

The bridges can only shorten the muscle fiber; they canít lengthen it. If the bridges remain connected, muscle tension is high, and you perform an eccentric action, the load is lengthening the fibers while the bridges are trying to shorten them. This is ďmechanical stress,Ē and itís the main trigger for growth.

Thatís why if you have zero control of the weight during the eccentric (very low tension), itís much less effective for growth. When you donít 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.

To maximize the mechanical stress, you must:

Create as many actin-myosin cross-bridges as possible, which is how a muscle contracts. The more force you need to produce, the more of those bridges you create.
Keep tension fairly constant during the rep. Thatís why too much acceleration can decrease mechanical loading. When you produce too much momentum, you need less force from the muscle to lift the weight, so you decrease the number of bridges formed.
Lengthen/stretch the fibers while the tension remains high. Less tension means fewer actin-myosin cross-bridges, which means less hypertrophy stimulation. Thatís why itís more effective to do the eccentric under control, not fast. The stretching of the fibers, while theyíre producing tension, is responsible for muscle damage and mTOR activation.
Recruit as many fibers as you can, create a lot of bridges in those fibers, and lengthen the fibers while as many bridges as possible are formed. Do that over several reps. Thatís it!

Okay, So What About Tut?

The number of reps is more important than the time under tension. With every rep you do, you have a new bout of mechanical stress via a new loaded-lengthening of the muscle fibers.

Here are two hypothetical scenarios to illustrate my point:

10 reps with 225 pounds and a 2010 tempo (2 seconds to lower, no pause at the bottom, 1 second to lift, no pause at the top). Thatís a TUT of 30 seconds because each rep took 2 seconds to lower.
5 reps with 225 pounds and a 5010 tempo. Thatís still a TUT of 30 seconds because each rep took 5 seconds to lower, but you did fewer total reps.

Even if the load and TUT are the same, scenario A is more effective.

Why? Because the number of times you stretch a muscle fiber in a set has an important impact on muscle damage and mTOR activation. Think of it like this: every time you get to stretch a fiber under load, you trigger growth.

Now, if you add a third scenario where youíre doing 10 reps with a 5010 tempo (a TUT of 60 seconds), would it be more effective? Nope! To do that, youíd have to use significantly less weight, probably something like 185-195 pounds instead of 225 pounds. The lower weight would lead to less muscle tension and each rep would be less effective.

Caveat: In that example, the longer time under tension will have some benefits that can increase muscle growth though. When you reach the 40-60 second range, if the intensity is high enough so that you reach failure in that time zone, youíll be producing a lot of lactate and growth factors, which can help with the adaptation to training.

The three scenarios in order of effectiveness would be:

10 reps at 225 pounds with a 2010 tempo
10 reps at 195 pounds with a 5010 tempo
5 reps at 225 pounds with a 5010 tempo

By completely decreasing tension during the eccentric and lifting explosively, you minimize mTOR and even muscle damage. This would be great for strength 22 and power, but not great for hypertrophy.

The new order would be:

10 reps at 225 pounds with a 2010 tempo
10 reps at 195 pounds with a 5010 tempo
5 reps at 225 pounds with a 2010 tempo

Growth-Factors1240◊698 172 KB

Does Tut Matter or What?

TUT will never be the main growth stimulus. All it does is lead to certain physiological responses, like lactate and growth factor production, which can play a small role in hypertrophy.

Local growth factors can help stimulate protein synthesis slightly (which speeds up muscle tissue repair and building), while lactate can increase follistatin levels which can inhibit myostatin a bit.

Lower myostatin leads to the possibility of building more muscle. But donít jump on the lactate bandwagon just yet Ė it likely wonít make a huge difference.

I do like to shoot for longer TUT on exercises that wonít cause much muscle damage. Think isolation work mainly, especially if the eccentric isnít loaded for the whole range, like lateral raises and barbell curls. This would be a good approach for people who have a harder time repairing muscle damage, like older individuals or people with very high stress levels.

For these cases, shooting for a TUT of 40-60 seconds with a moderate weight can be beneficial.

By the way, I use a lot of slow eccentrics. Iím not being contradictory: I use them for reasons other than stimulating maximum growth, like improving motor learning, strengthening tendons, and becoming stronger eccentrically.
liftsiron is online now   Reply With Quote
Old 03-06-2023, 11:16 PM   #2
Dawgpound_Hank's Avatar

Join Date: May 2019
Posts: 966
Dawgpound_Hank has a spectacular aura aboutDawgpound_Hank has a spectacular aura aboutDawgpound_Hank has a spectacular aura about
Good read!
Dawgpound Hank is a fictional character,. All posts by my character are merely for entertainment purposes and not meant to be taken seriously.
Dawgpound_Hank is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT -5. The time now is 08:56 PM.

Powered by: vBulletin Version 3.8.11
Copyright ©2000 - 2023, Jelsoft Enterprises Ltd.