Concentric, Isometric, Eccentric

The 3 phases of every dynamic exercise.

Concentric, isometric and eccentric are words you may have heard before without really understanding what they mean, or you may not know why it is important to differentiate the three.

Dynamic exercises are exercises where you perform repetitions of one or several moves, as opposed to exercises that may only require to hold a position for a desired length of time.

Repetitions usually involve moving a body part in one direction, and then moving that part in the opposite direction to the return to the original position. Example: a push-up consists in bringing the chest to the floor (going down), and pushing the chest back to the original position (going up). These are the 2 phases we will describe first.

The concentric phase is often defined as the shortening of the muscle being trained, and the eccentric phase as the lengthening of the muscle being trained. Not clear? We know, and this is why this article was written.

When you perform an exercise, you are usually aware of which muscles you are using, or at least you are aware of which part of the exercise requires more effort.

The part which requires more effort, which requires more contraction, and which really engages the muscles being trained is called the concentric phase. Example: pushing your body up when performing a push-up, or pulling your body up when performing a pull-up.

The opposite part which is a bit more “relaxing” and could be compared to “loading” is called the eccentric phase. Example: Bringing your chest to the floor during a push-up, lowering your body down during a pull-up.

Attention: the eccentric phase doesn’t always mean returning to the original position. Example: If you are doing squats, to return to the original position you need to contract your leg muscles to push your body up and this is where you are really engaging strength and producing the effort. It is the concentric phase that brings you back to the original (standing) position.

Concentric phase: effort, eccentric phase: loading before producing effort again.

So what is the isometric phase? It’s the most simple one. The isometric phase is simply the part between the concentric and eccentric phases, when your body is not moving.

Now that you know and can name the 3 phases of an exercise, you may wonder why we even need to know this when all we want is to train!

Well, you need to know this because these different parts need to be treated differently and you will often receive instructions that only apply to one phase or another.

First of all, it is very important to know when to breathe during an exercise and here is a universal tip for you now that you know what these words mean: inhale during the eccentric phase, exhale during the concentric phase. Read that again, thank us later.

Another good reason to know these words is because sometimes you will be asked to perform repetitions with a specific tempo. You might be asked to take 1 second for the concentric phase, 1 second for the isometric phase, and 2 seconds for the eccentric phase. Example: to perform a push-up, take 2 seconds to lower your chest to the floor, pause for 1 second at the bottom, take 1 second to push yourself back up. By the way, you should actually try this!

And another one: did you know that “negatives” were great for building strength? Negatives consist in performing only the eccentric phase of an exercise which is currently too difficult for you, and doing so as slowly as you can. Example: if you can’t do a pull-up, start with your chin above the bar and lower your body as slowly as you can (at least 5 seconds if possible), you will gain pulling strength much faster.

This technique can be applied to almost every exercise, you just need to remember what the eccentric phase is.

That’s all about concentric, isometric and eccentric. We hope this article helps and that you found a few tips you can apply to your training today!