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Are you looking for a new way to spice up your workout routine?

Well, I’m sure you are aware of the two different muscle contractions like concentric and eccentric.

For concentric, think of a bicep curl. When you curl the weight you are shortening the muscle length, creating a concentric contraction.

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Now using that same example, when you bring the weight down, you are lengthening the muscle creating an eccentric contraction. The muscle tenses as you lengthen the muscle.

With a concentric and eccentric contraction put together, you create a combination of fired up muscle motor units and tearing muscle fibers. This allows you to get bigger or stronger. But, there’s got to be something else out there right?

Did you know there was a third type of muscle contraction? Yes!

It is called an isometric muscle contraction. It is used to perform isometric exercises every day and not many people know about it.

What are Isometric Muscle Contractions?

In short, it is when you are holding a particular tension or resistance at one fixed spot, so you aren’t performing a concentric or eccentric effort, but still creating strength in the process. ​

ScienceDirect​ says, “Isometric strengthening occurs when the force generated by muscle and the external force is the same and there is no lengthening or shortening of the muscle.”

An example of an isometric exercise would be a wall squat or wall sit exercise because you are holding your weight and muscles in one position cutting out the concentric and eccentric, shortening and lengthening, part of the muscle fibers.

You are adding tension to your muscles by forcing them to keep you up, which can be harder than most concentric or eccentric contractions.

Now, let’s take a look at two types of isometric contractions and their exercises, Submax and Max.

Two Types of Isometric Muscle Contractions

There are two types of isometric contractions you can use in training. One being called submax and the other is called max.

Submax Isometric Exercises

Say you are holding a weight in your hand in front of you and with your elbow at a 90-degree angle. By holding it in the one spot, and not moving, you are cutting out the concentric and eccentric part of the move. Essentially you are letting gravity and the weight be the stressor on your muscle.

This particular move is called a submax isometric exercise. With a submax move, you are able to push against something and feel your muscles engage but still allowing yourself to maintain control of it.

Examples of submax isometric exercises are doorway presses, a wall sit, plank and the superman.

All of these exercises are considered a type of submax isometric movement.

When performing a submax isometric exercise it is crucial to hold your contraction for 30-60 seconds for each move. Submax training frequency and volume are much less than max isometric efforts, you are actually able to perform it longer, so could go well over a minute for each exercise.

Max Isometric Exercises

You’ve heard about submax, now let’s talk about max isometric exercises.

Now let’s say you are holding a chain in your hand, with your elbow at a 90-degree again, but with a weight that you can not physically lift on the other end.

No matter how hard you try to lift that weight, you won’t be able to lift it off the ground. That force you create when you are trying to lift unmovable weight is what you call a max isometric move.

A lot of research shows that max effort affects your central nervous system, also known as CNS, a lot more than in a submax effort. But, the max isometric effort recruits all of the motor units in your muscles, so the best way to describe max isometric exercises are as high-intensity training.

The most effective way to go about this is by doing the move for less time and less sets with longer rest periods. The training frequency for max isometric efforts is much less than submax because it affects the central nervous system more.

What you want to do is hold the weight for 5-10 seconds and try to build up to 5 sets total in a session. You will want to pick four days out of the week to repeat the same process.

The Bottom Line on Isometric Muscle Contractions

It is important to know the difference between submax and max isometric exercises.

There are many different training protocols out there when actually dealing with a submax or max move. Take a look at the ​video​ above for an even deeper look into the difference between submax and max contractions.

If you’re a beginner it is a great way to initiate functioning muscle motor unit recruitment when you are struggling with the concentric and eccentric part of other exercises.

Now that you are aware of these types of isometric muscle contractions, I challenge you to observe yourself when you workout and just see how many times you actually perform an isometric exercise without ever realizing.

isometric contractions


Chris Cannon
Chris Cannon

Hey Chris Cannon here, founder of Free Muscle Building Tips. I hope you enjoyed this post. If you haven't done so already be sure to subscribe to our newsletter and get your free Six Pack Abs Secret Weapon Workout!