February 9, 2014

Load VS. Time Under Tension - What's More Important For Building Muscle?

The formula for results

Regardless of what motivates you to utilize the time you have to get into the gym and push yourself to create some sort of physical change (increase strength/muscle mass, or decrease bodyfat/improve endurance), the equation (if there ever was one) for getting results is, and has always been:

Load X Time Under Tension = RESULTS! – The amount of weight you can lift multiplied by the duration in which you can generate tension. If you want to get any sort of result in the gym, you better familiarize yourself with this formula! Anything you do, either exercise-wise (how you perform), or programming-wise (when you perform), that takes away from either variable in this equation will negatively affect the end result


The only difference between one person’s goals and another’s, is the way in which you manipulate the loading parameters to tip the scale in favor of one side of the equation, or the other.

For example, one looking to get stronger would want to tip the scale heavily towards the load side of the equation, while one looking to improve endurance, or their ability to repeat efforts, would want to tip the scale heavily towards the time under tension side of the equation.

One looking to build bigger muscles, or improve body composition (which also happens as a result of building muscle), would ideally like to hover somewhere in between, occasionally devoting phases of training towards each end of the equation, as they build upon each other, and equally contribute to attaining the end result.

We don’t live in a perfect world, get used to it

In a perfect world, one would be able to maximize both ends of the formula for results, and lift maximum weights for extended periods of time. Unfortunately, that’s just not possible, so one has to decide which end of the equation they’re willing to sacrifice in favor of the other.

Load VS. Time Under Tension

If your goal is performance based, either strength development or increased aerobic capacity, then your decision is pretty much made up for you beforehand. However, if your goal is aesthetics based, either building more muscle, or reducing bodyfat, it can be rather challenging to determine precisely what the best method is for you.

Do you lift heavier, and hope that the elevated level of motor unit recruitment, fast twitch muscle activation, and positive testosterone response associated with heavy weights will get you the result you’re looking for?

Or do you lift relatively lighter, and hope that the pump, occlusion hypoxia, and positive growth hormone response associated with prolonged time under tension will get you the result you’re looking for?

Can’t I have both?

There are a myriad of ways in which the loading parameters can be adjusted to get any desired result. So, in short, you could essentially develop a program that allows you to train in a way where you maximized the load, as well as time under tension, just not at the same time.

A little over a decade ago, strength coaches (primarily two of my idols – Charles Poliquin, and Ian King) began touting the benefits of increasing the time under tension, by simply prolonging the duration of the eccentric portion of the rep. In theory, this makes great sense, as we are stronger eccentrically, and isometrically, than we are concentrically. This basically means that are muscles are not fully stimulated when we traditionally perform repetitions in which the lifting and lowering of a weight is done at roughly the same tempo. By slowing down the eccentric, or briefly pausing and creating a ‘peak’ contraction, you increase the duration in which the muscles are generating tension, and therefore should be an easy way to maximize both ends of the formula for results, right? WRONG!

Objects in mirror are closer than they appear – (things aren’t always as they seem)

By enhancing the eccentric or isometric portion of the rep, you are increasing the workload indirectly. Indirectly because you aren’t actually increasing the load, only the effort required to lift the load. This means the total overall volume, or tonnage lifted, over the course of a workout is reduced.

For example, if you can perform 10 reps, with 225 lbs, irrespective of the time it takes to complete the reps, given that your form was at least ‘good’, you will have lifted a grand total of 2,250 lbs. Depending on the quality of the repetitions, the length of the limbs, and the distance the bar travelled (which is determined by the actual exercise performed), it’s safe to say that set could take anywhere from 15-30 seconds.

Now, take that same weight, and add an eccentric and/or isometric component to it, and it’s likely you end up with half as many reps, in the same amount of time. Aside from the dramatic reduction in reps, this means to get as many reps, you will need to use a dramatically lower weight, because it’s not as easy to say ‘just slow things down to maximize the time under tension’, and still expect to perform the same (rep-wise). Granted, your time under tension for the same amount of reps will be greater, but the load part of the equation is compromised.

So, while the time under tension may be the same if you opt to NOT reduce the weight, the overall volume in terms of tonnage lifted, is dramatically lower if you try to maximize both components of the formula for results AT THE SAME TIME! This isn’t to say that enhanced eccentrics or isometrics aren’t of value, because they are.

There’s a time, and a place

There are many benefits to emphasizing both the eccentric portion of a rep, and pausing at both the top and bottom of the rep (or anywhere in between), and to go through them goes beyond the scope of this article. However, there is a time and a place for everything, and unless your training for strength, in which you’re using supramaximal loads eccentrically, or trying to move an immovable object isometrically to prime your nervous system for the work to come, then logic (as demonstrated above) would suggest that the use of eccentrics and/or isometrics is best suited at the end of a set/workout as a way to increase the time under tension WITHOUT compromising the amount of weight lifted, and therefore total volume of the workout.

Take a look at the bigger picture

One way of determining whether or not a method is of great value to you, is to look at what those who have had success have done, and how they have done so. While building muscle is a result of the time a muscle is under tension for, those with the most muscle (professional bodybuilders) don’t generally use slow eccentrics when they’re fresh.

Even powerlifters, who generally overanalyze, and dissect, each and every lift, in attempt to maximize performance, often save paused work for later in a training session when trying to make improvements for a given lift, due to the submaximal loads needed to prolong the time under tension, though there are occasions when the goal is to develop starting strength/rate of force development when they’re fresh, and ready to rock. As for eccentrics, the only reason they would prioritize the eccentric portion of a lift is because it’s simply unsafe to lower hundreds of pounds rapidly (and expect to be able to reverse the movement and complete the lift). Slowly lowering enables them to maintain high levels on stability so that they can successfully complete the lift.

Work hard, play hard

At the end of the day, muscles respond to tension, or ‘work’, for the lack of a better term. The more ‘work’ they do (within their capacity to recover), the more they will grow (this is maximized through adequate nutrition, hydration, and rest). This ‘work’ can be measured in terms of volume. Volume, or tonnage, is the summation of the amount of weight lifted, multiplied by the amount of reps performed (as long as they are quality reps).

When you attempt to increase the time under tension by enhancing the eccentric component, or adding an isometric component to one or more parts of the rep, you negatively affect the amount of work your muscles end up doing. While there are benefits to emphasizing eccentric and/or isometric contractions, they should be limited to very specific phases of training, lifting very heavy weights to prevent injury, or later in the set/workout AFTER you have accumulated an optimal amount of volume (which is the result of lifting heavier weights for more reps). Then, you can play around with enhanced eccentrics, or isometrics, to increase the time under tension, since the amount of weight you can lift in a fatigued state is limited anyway.

If you have any questions about the formula for results, or either load vs. time under tension, feel free to contact me at ben@paramounttraining.ca. I'm available for online consulting and personalized program design, as well as one on one training if you are located in the Greater Toronto Area (GTA).

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