When it comes to building muscle there are countless methods that people will look to use, this unfortunately means however that there is always debate at which method is best, especially when it comes to muscle hypertrophy.
One particular debate is often whether or not you should focus on time under tension or heavy weight to stimulate muscle hypertrophy. The two are not mutually exclusive meaning you can do both at the same time however this is only true to a degree.
Time under tension vs heavy weight? While you will eventually need to work up to a heavy weight to continue building muscle over time, heavy weights alone will not build muscle. Heavy weight for low reps will build explosive power and strength but a certain time under tension of 45-90 seconds is often required for muscle growth.
It’s important to note that the two principles alone do not prevent you from utilizing both at the same time, the real question comes down to the individual’s perspective of heavy weight and it is also based on their relative level of strength.
A 315lb bench press might be considered heavy for most however if you factor in the lifters 1 rep max might be 455lbs then you can see that whilst it is certainly heavy weight it’s not considered to be heavy to the individual. This is when the amount of reps you do also need to be factored in but we will come on to that later on.
Time Under Tension vs Heavy Weight for Muscle Hypertrophy
If you are just starting out in weight training then chances are you have been bombarded with a range of principles and techniques that you absolutely must be using in every workout, this even becomes true for intermediate to advanced lifters.
The more you learn about building muscle the more techniques you seem to discover in the process and this can make it very confusing when you come to planning your own workouts. One very contradictory method is time under tension vs heavy weights.
It’s obvious what the term heavy weight means however you might not be too familiar with the time under tension approach.
What Is Time Under Tension
Time under tension (TUT) is the length of time that your muscles are placed under tension. It sounds simple enough but if you are doing a squat and stand upright for a full second after completing a rep then the amount of tension on your legs is minimal during this period.
The same can be true of a bicep curl, if you let your arms hand by your side in between reps then the tension on the actual target muscle is reduced.
This distinction is important to make as TUT is an important concept to keep in mind when it comes to building muscle. It’s not only the number or reps that you do that contribute towards muscle damage (and ultimately growth) but also the load and length of time that your muscle is under active tension.
How Do You Calculate Time Under Tension
Now that you know what TUT is it’s important to not that there are two ways that you can calculate the TUT of a set. The first is the tempo of your reps and the second is the length of time that a particular set lasts.
For muscle hypertrophy purposes, the ideal set length should be between 45-90 seconds to maximally produce muscle hypertrophy. Any less than this and you won’t sufficiently stimulate hypertrophy and any longer will see the set become endurance based.
This timeframe is good to note because the length of time a set lasts will be dictated by the weight you can lift and vice versa so we will cover that later.
Time Under Tension Tempo
The tempo of each rep will have a significant impact on the length of time that a set lasts. Many beginners will hammer out reps as quickly as possible while using momentum to help with each rep and pay no attention to tempo.
A suggested tempo for a bench press rep could be 1-1-3-1, broken down this is the following:
- 1 second to lift the weight (concentric portion of the movement)
- 1 second squeeze at the top (forcing blood into the active muscle)
- 3 seconds to lower the weight (a controlled eccentric)
- 1 second stretch at the bottom
As you can see many will not follow a slow controlled eccentric and even few will actively contract or stretch the muscle during the rep. What you can see however is that this tempo would take 6 seconds to complete a single rep.
If the ideal set length for hypertrophy is 45-90 seconds then performing 8-12 (the ideal rep range for muscle hypertrophy) will see you fall within this timeframe. Very handy but I wouldn’t call it a coincidence!
You’ll also be able to see that if you followed a rep range similar to a 1010 then your set will be over very quickly and you won’t have had enough time to place the muscle under an active load. Explosive reps play their part in workouts but less so when it comes to maximally building muscle tissue.
Time Under Tension Set Length
The set length however can be determined by a set amount of time in which you complete your reps. This can be done with a literal timer or by selecting a weight that you will fail at within a set time (ideally 45-90 seconds).
This is less conventional but a heavier weight will naturally take longer to perform reps with as you need to control the weight and not every rep will be done so easily.
Tempo works well but some don’t like to count reps and instead do a set to (or very close to) muscle failure in order to fatigue the muscle fibres. If you are someone that doesn’t count the number of reps you do then instead setting a timer will ensure you perform reps until the allotted timeframe and will therefore maintain TUT.
The method you choose is very similar and will all get the same result which is in the end an extended period of TUT.
Does Time Under Tension Build Strength
While many think that lifting heavy weights is the only way to build strength you’ll be surprised to hear that lifting heavy weights only builds strength in one specific range and that is the concentric portion of a lift.
It’s important to note that concentric strength is not the only form or strength, you are roughly twice as strong in the eccentric (lowering) portion of a movement than you are in the concentric phase. Therefore neglecting this means you will leave progress on the table and you can also be strong in an isometric which involves holding tension at a certain point like in a plank.
As there are different strength planes it’s important to utilize TUT in order to build overall strength. It’s definitely true that improving your 1 rep max in heavy compound exercises will increase overall strength but that is not the whole story.
If you are twice as strong in the eccentric phase then you should be looking for ways to target this in order to not only increase your overall strength but to also illicit more muscle growth.
I used an example earlier that gave a rep tempo of 1131 and this was not coincidental. Taking longer to perform the eccentric portion of a lift will not only increase the TUT for more muscle growth but will also fatigue and strengthen the slow twitch muscle fibres that are needed to lower a weight under load.
It’s also why I used the example of someone blasting out reps with no conscious thought given to the lower portion of the movement. It’s easy to fly through reps and think you are working the muscle group but to really activate a muscle and create metabolic stress you also need to control the weight when you lower it.
A focus on eccentrics will therefore increase the TUT but also contribute to strength increases. If you want to see more about the benefits of negative training then you can do so here and here to see the studies that support eccentric training for strength gains.
How Long Should You Be Under Tension to Build Muscle
To round this off then, hopefully you understand the importance of time under tension when it comes to muscle growth and that it’s not all about lifting heavy weights.
What I did allude to however is that you do still need to lift heavy weights in order to build muscle but it needs to be relative to your 1 rep max. This is important because if you take heavy weights at face value and literally lift your heaviest weight for an exercise then you are limited to 1-3 reps per set.
This is not enough time to adequately stimulate the muscle and you will be training purely for strength and explosiveness in these ranges. Therefore you need to lift heavy but at a percentage of your 1 rep max.
The percentage you choose should be between 80%-90% depending on the exercise and your current strength level. If you can bench press 225lbs for a single rep then you will want to do your working sets at 180lbs for 8-12 reps.
This can still be considered heavy weight but as it’s based on your 1 rep max you will then be able to perform enough reps to get the TUT required for muscle hypertrophy.
If you follow general guidelines of 8-12 for most generic programs online then you won’t know what weight to select and this is where the confusion over heavy weight vs time under tension comes in.
If however you are using a percentage based system to select your weight then you will be using a heavy weight relatively speaking. These minor adjustments to your thinking and programming are what will help you to build muscle in the long run and differentiate between legitimate scientific principles and other regurgitated nonsensical information found online.
If you don’t know your 1 rep max then you can check out this handy online calculator to work this out for you, just note that it will be an estimate to use as a reference point.
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Rest pause training vs straight sets
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