Isometric, Isotonic, Concentric, Eccentric... What Does It Even Mean!?

If you’ve been around rehab or gym people, you’ve likely heard terms like isometric, isotonic, concentric and eccentric thrown around. But what do they even mean??

When we talk about exercises, we generally break them down into two types: isometric and isotonic. Isotonic exercises can be further broken down into concentric and eccentric parts of the exercise. All have an important role in exercise and rehab.

The language can be confusing so let us be your guide - we promise, it’ll make sense by then end!

Isometric Exercises

Isometric exercise refers to an exercise where you hold one position, meaning the muscle stays still and does not move through a range of motion. Some great examples of isotonic exercises include wall squats and planks. Isometric exercises may be held from anywhere from a couple of seconds to over a minute.

Isometric exercises are fantastic for improving stability of a joint. They are often used in rehab as they can be lower impact that other types of exercise.

We often use isometric exercises when moving through a full range of motion is painful. While isometric exercises can help you build strength, they will likely not be as beneficial for improving power output or speed in the long term. Recent research has shown the benefit of using isometric exercises for strengthening tendinopathies, so we often do these types of exercises for injuries like patellar tendinopathies, Achilles tendinopathies and tennis elbow.

Isotonic Exercises

Isotonic exercise refers to an exercise where a joint is moving through a range of motion. Examples of an isotonic exercise would be a bicep curl, squat or a push-up. In each of these exercises you move a weight (whether that be body weight or additional weight, like a dumbbell) through a range of motion.

Isotonic exercises are fantastic for gaining strength and can be adapted to focus on different goals such as power, speed or increasing range of motion.

Isotonic exercises can be broken into two main types:

1. Concentric - the portion of an exercise where a muscle is shortening.
   
   With an concentric movement, tension in the muscle increases to meet the resistance of the weight, moving the weight in space. An easy example of a concentric contraction would be the part of a bicep curl where you are lifting the weight up towards your shoulder by bending your elbow.
   

2. Eccentric - the portion of an exercise where a muscle is lengthening.
   
   With an eccentric movement, tension increases are you lengthen the muscle and control the weight as it goes down with gravity. An easy example of an eccentric contraction would be the part of a bicep curl where you are lowering the weight back towards the ground.

While isotonic exercises contain both a concentric component and an eccentric component, you can alter exercises to put more emphasis on one part of the exercise to reach certain goals. Both eccentric and concentric exercises are shown to increase muscle strength, muscle mass and power output.

While the research is not conclusive, some research has shown that focusing on the eccentric portion of an exercise may help to increase muscle strength and growth more than the concentric portion. One way to achieve this is to slow down the portion of an exercise where you are lengthening the muscle (e.g., slowly lowering the dumbbell in a bicep curl, slowly lowering the bar on a chest press, or slowing down how quickly you drop towards the ground in a squat).   

If you have questions or need help figuring out to use these exercises to meet your goals, be sure to book in with our registered kinesiologist for support.

 Give us a call at (778) 630-8800, email us or book online to seek treatment from a physiotherapist or to work with a registered kinesiologist.