You probably see them in your gym sometimes: those guys who do super fast reps, with a shortened range of motion, without giving the muscle even one moment of rest during the set. Constant tension, we also call this way of training. It is certain that you feel the muscle burn during such a set, but does that also result in more muscle growth than ‘normal’ training, ie with very short breaks between reps?

Key points:

1. Constant tension is a training technique in which you keep constant tension on the target muscle during a set by allowing the repetitions to more or less flow into each other. You do not use short breaks between the repetitions, you cut something from the range of motion (ROM) where necessary and you minimize momentum. With this way of training you have to use lighter weights to be able to make enough reps.

2. Non-constant tension is the traditional way of training with short breaks between reps, with full ROM and a little momentum. With this way of training you can use heavier weights.

3. To build muscle optimally, you must do enough sets with sufficient effort (i.e. train to near muscle failure), and use increasingly heavier weights over time. As long as you meet those conditions, it probably doesn’t matter much which training technique you use: constant tension or non-constant tension. After all, the difference between the two training styles is compensated by the amount of weight you can use.

4. You may be able to achieve ‘extra’ muscle growth (namely: sarcoplasmic muscle growth) by including some metabolic strength training in your training program, for example one exercise at the end of the training. Constant tension is then one of your tools to create more metabolic stress, in addition to doing supersets, for example.

5. Constant tension is best used for exercises where the target muscle is not (optimally) activated over the entire ROM, such as lying triceps extensions/skull crushers, chest flyes, dumbbell lateral raises and dumbbell pullovers.

6. With large compound exercises such as the squat, deadlift and bench press, it is better not to apply constant tension in order to be able to use heavy weights and at the same time maintain a correct technique.

7. Constant tension training is a good alternative if you can only train with light weights, for example in the aftermath of an injury.

TENSION IS KEY

One thing should be clear: in order to grow, a muscle must ‘experience’ sufficient tension during a workout.

In the past, what is ‘sufficient’ was often indicated in time, namely by means of Time Under Tension (TUT). However, this method is somewhat outdated or at the very least causes confusion. With a set of 20 repetitions until muscle failure (light weight), a muscle is under tension much longer than with a set of 6 repetitions until muscle failure (heavy weight), while both sets are in principle equally effective for muscle growth.

With muscle growth, it is about making sufficient effort during a set (ie training to or close to muscle failure), regardless of the weight of the training weight. That is why we prefer to speak of effective (or stimulating) repetitions instead of TUT. That’s roughly the five heaviest reps of a set, the one right before muscle failure, regardless of how many reps you do in total.

Because five effective reps, on a weekly basis, is not enough to stimulate muscle growth, we do several sets for each muscle group : an average of 10 to 20 per week. The tension that you apply to a muscle is roughly 50 to 100 effective repetitions per week. It is better not to do 10 sets per muscle group per training, so a maximum of about 50 effective repetitions.

In addition, the repetitions will gradually have to become heavier because you gradually increase the training weight: progressive overload.

In short, regardless of your training style, training split or whatever, you should:

Train your sets to near muscle failure (use an average of 1-3 RIR) (effort);
Do enough sets (10-20 per muscle group per week, 1-10 per workout) (volume);
Gradually train harder by increasing the training weight over time (overload).

In addition, most coaches agree that during an exercise you:

usually use a full range of motion (ROM), meaning you use the entire range of motion of the exercise;
for an optimal growth stimulus to a muscle, the strongest possible mind-muscle connection with that muscle must be achieved.

WHAT IS CONSTANT TENSION?

Constant (or continuous) tension means that you keep tension on a muscle throughout a set. You do that by:

no rest breaks between repetitions, not even minimal ones;
shorten the ROM slightly, ie cut off the first and/or last piece of the ROM;
minimizing momentum.

For the record: it’s not about partial reps, because you only eliminate a small part of the ROM, usually only a part in which the target muscle is less activated.

In this way the reps flow into each other, so that the tension remains on the (target) muscle and you can also benefit much less from momentum. Momentum is especially created when you use heavy weights and full ROM, allowing gravity and the activation of other muscles to facilitate the movement.

The consequence of constant tension is that the exercise becomes much heavier. As a result, you reach the moment of muscle failure much faster in your sets. With constant tension you will therefore have to sacrifice a lot on training weight or number of repetitions. The sets also feel more stressful than regular sets.

Often with constant tension, very fast or very slow repetitions are also done, although neither is necessary.

CONSTANT TENSION FOR MORE MUSCLE GROWTH?

Is constant tension a training technique that is preferable to sets in which you occasionally give your muscles some breathing space? In short, are constant tension sets more effective for muscle growth? Views and opinions on this vary widely. We discuss the vision of five renowned bodybuilding coaches.

SEAN NALEWANYJ

Coach Sean Nalewanyj thinks it doesn’t really matter how you do your sets – with or without constant tension – as long as you meet the three conditions for muscle growth: train to near muscle failure, do enough sets and apply progressive overload. With constant tension you can also train to near muscle failure, only with a lighter weight and/or with fewer repetitions. Make sure you create around five effective reps per set. If that doesn’t work, you should use a lighter weight.

According to Nalewanyj, constant tension is somewhat similar to blood flow restriction training, where you train with low weights and still create a growth stimulus that is equivalent to that of normal training with higher weights.

And the greater training stress you experience with constant tension? According to Nalewanyj, this says nothing about the degree of muscle growth. After all, long sets with low weights also hurt more and bring more ‘pump’ than short sets with high weights, but the effect on muscle growth is the same, provided that the sets are trained to near muscle failure.

Nalewanyj also points out that the traditional way of training, without constant tension, has more than proven itself. Just look at the barbell squat: an exercise that gives many natural bodybuilders monstrous quadriceps, while with that exercise they usually pause relatively long between reps.

Constant tension is an effective alternative to traditional training when you can only use light weights, for example in the aftermath of an injury.

MIKE ISRAELEL

Another authority in bodybuilding land, Mike Israetel, is not very enthusiastic about constant tension. Although he acknowledges that constant tension training can have a place in a training program, he thinks that it is generally better to take a short break between reps. He states:

Tension causes growth, not constant tension.

In addition:

Rest between reps lets you reset for better technique and mind muscle connection. It lets you get more reps per set, and it lets you be near failure for more of those reps.

Israetel points out that thanks to those short breaks you can do more effective repetitions than with constant tension.

On the other hand, you create more metabolites with constant tension, Israetel also acknowledges, and metabolic training may lead to ‘extra’ muscle growth, namely sarcoplasmic hypertrophy. You can compare it to doing supersets; by quickly switching between exercises you keep your muscles under constant tension. Israel does say that you can only do a small number of metabolic sets per workout because of the great acute training stress. Too much metabolic training can therefore be at the expense of the mechanical tension that you provide per training. And mechanical tension is the main mechanism of muscle growth: it is responsible for most myofibrillar muscle growth.

All things considered, according to Israetel it doesn’t really matter whether you train with or without constant tension:

You don’t have to pause between reps, but you almost certainly don’t have to apply constant tension either.

BRAD SCHOENFELD

Hypertrophy researcher Brad Schoenfeld disagrees entirely with Israetel. In 2016 he wrote:

Muscles respond favorably when they’re placed under continuous tension with no resting phases during the rep.

This was partly based on a study from 2008. By that response he means the great metabolic stress that constant tension training causes in a muscle.

We now know that metabolic stress as a training mechanism for muscle growth is subordinate to mechanical tension. But it also seems that training with a lot of metabolic stress can be a useful addition to traditional training, because metabolic stress may stimulate another kind of muscle growth, namely the sarcoplasmic muscle growth that we already mentioned.

Schoenfeld does think that the big basic compound exercises, such as squats, deadlifts and bench presses, are best performed without constant tension, so with short breaks and with some use of momentum. That way you can perform those exercises heavily without having to compromise on technique. For more isolating exercises, he recommends constant tension, especially in exercises where the ends of the ROM cause little activation of the target muscle, such as chest flyes and dumbbell pullovers.

GREG NUCKOLS

This view seems to be confirmed by the surprising outcome of a 2017 study by Goto et al. In this study, the effects of skull crushers performed with partial ROM (with constant tension) and full ROM were compared. After eight weeks, the partial ROM group had achieved almost twice as much muscle growth in the triceps as the full ROM group.

Impressive results, according to coach and author Greg Nuckols of Stronger by Science, who does not rule out that the ‘partials’ simply had trained harder because of the training protocol and therefore achieved greater gains .

Nevertheless, Nuckols considers it conceivable that constant tension can indeed be an effective training method, especially for exercises with a circular resistance curve, such as chest flyes and skull crushers.

MENNO HENSELMANS

Coach Menno Henselmans, on the other hand, questions the measurement methods used in the Goto study. He also points out that especially with skull crushers the full ROM is pretty bad and partials are therefore not really inferior to it. Finally, he once again cites some studies whose results are clearly in favor of full ROM (and non-constant tension). Not that Henselmans completely writes off constant tension, because he concludes:

Future research may help clarify this lone study’s deviant findings. For now, however, it is at least another data point in favor of chasing high muscle activation levels in your training. Partials can achieve this, but you’d likely get better results by selecting exercises with an inherently good resistance curve, so that you can overload your muscles along their entire length without having to compromise on ROM.

CONCLUSION

Research shows that it doesn’t matter that much whether or not you use constant tension, as long as you make enough effort (ie: train until near muscle failure).

Fortunately, you don’t have to choose. Especially as an advanced athlete, you may do well to do some metabolic strength training in addition to traditional bodybuilding training. For example, on a weekly basis 75% regular training and 25% metabolic, preferably spread over several training sessions and then always at last in the training. This way you can take full advantage of both muscle growth mechanisms, mechanical tension and metabolic stress, translating into optimal myofibrillar and sarcoplasmic muscle growth.

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