Man doing lying leg curl exercise in gym

Does constant tension actually build more muscle?

What is constant tension?

Constant tension is an intensity technique used to maximize a muscle’s workload by subjecting the muscle to uninterrupted tension. This consistent stress placed on the target muscle group is primarily accomplished by intentionally reducing an exercise’s range of motion to avoid joint lockout. Additionally, constant tension sets often use a controlled tempo devoid of any cheating or momentum usage.

In the minds of many, constant tension is almost always a positive in the context of muscle growth. However, this presumption is often supported solely by anecdotal evidence, such as a person feeling a stronger-than-usual burn when using this technique.

This begs the question: is constant tension actually beneficial for muscle growth, or is it simply another overrated intensity technique?

The case for constant tension

Why it’s supposed to build more muscle

The fundamental principle on which the constant tension technique is based concerns the buildup of metabolites. By forcing a muscle to contract continuously, the muscle is essentially suffocating for the duration of the set, as it has no chance to ‘breathe’. This creates a hypoxic environment in which the muscle does not receive sufficient oxygen, resulting in the burning sensation felt during strenuous exercise. The oxygen-deficient environment created by this style of training is thought to drive anabolic signals that indirectly lead to increased muscle growth.

Time-efficiency

By maintaining consistent tension on a muscle throughout an exercise, an individual is able to reach muscular fatigue in the least amount of time. This training style can be a very viable option for people who are limited in how much time they can dedicate to their daily workouts.

A reduction in peripheral fatigue

When performing most compound exercises, it is very common for fatigue to be felt in both the target muscle(s) and secondary, supporting muscle groups. For example, the abdominal muscles often fatigue faster than the leg muscles do in most free-weight squat exercises despite not being the target muscle group. This is frequently referred to as ‘peripheral fatigue’, although this term can also be used to describe any fatigue that is centralized within an exerting muscle.

In most cases, fatiguing in a secondary muscle group is never a good thing, as it takes away from one’s ability to sufficiently exhaust their target muscle group. By utilizing the constant tension technique, a lifter should be able to adequately fatigue their desired muscle group without a secondary muscle group stopping their set short. For example, choosing to perform a barbell squat without fully standing up at the end of each rep will maintain consistent stress on the quadriceps muscles. Ideally, this should allow the individual to fatigue their quadriceps in a shorter amount of time, allowing them to finish their set before their abdominal muscles become too tired.

The case against constant tension

Understanding tension

The largest misconception when discussing the importance of constant tension revolves around the fact that ‘constant tension’ and ‘tension’ are two separate variables. As explained in our article about the three mechanisms of muscle growth, (mechanical) tension is the most important factor in the muscle-building equation. This tension variable specifically concerns how much force the muscle fibers are producing throughout the course of an exercise, not for how long they produce that force.

The distinction between these two terms is not just a matter of semantics; one refers to how long a muscle experiences stress while the other concerns how much total stress—difficulty included—that muscle experiences during an exercise. Basically, the duration for which a muscle experiences tension is irrelevant without accounting for how demanding that tension is.

Fewer effective reps

In the past decade, researchers have concluded that significant muscle growth adaptations only occur when a set is taken within four or fewer repetitions of muscular failure. These four important repetitions are appropriately referred to as ‘effective reps’.

When utilizing the constant tension technique, momentary muscular failure is almost always achieved. However, since these sets don’t allow for breaks of any kind, the set ends when this momentary exhaustion occurs. Unfortunately, this can prove to be detrimental to an individual’s potential muscle gains, as they often miss out on additional effective reps that they would’ve completed had they taken a brief rest between their final repetitions. Luckily, the easy fix to this predicament is to momentarily rest after reaching muscular failure on a constant tension set before pumping out a few additional effective reps.

Can promote poor form

Since the constant tension technique requires an individual to use a reduced range of motion, some people get carried away and use it as an excuse to perform half-repetitions. While half-reps can undoubtedly be a viable option as an intensity technique, training a muscle through its entire range of motion is essential for significant muscle growth adaptations to occur.

It is important to remember that the reduced range of motion seen with this style of training is simply supposed to avoid joint lockout; this change in range of motion should be subtle and shouldn’t heavily alter the exercise.

Case closed

After comparing the pros and cons of constant tension, it should be somewhat clear that there is nothing inherently wrong with using this technique. In fact, there is not a single negative aspect to this training style that should dissuade someone from using it.

With that said, consistently maintaining uninterrupted tension on a muscle doesn’t necessarily cause any additional muscle growth when compared with normal training. For this reason alone, constant tension should be seen as a tool, not a necessity.

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