Isometric vs Isotonic Exercises: The Differences and How to Use Them

Learn How You Can Balance the Benefits of Isometric and Isotonic Exercises for Peak Performance in Your Training.

You can do two types of resistance exercises in the gym: isotonic and isometric. Each has unique benefits and uses within your training program.

By adequately incorporating each, you can maximize your gains in the gym, avoid injury, and elevate your performance to new heights.

In this article, we will explore these two types of exercises, their benefits, and how they fit into an evidence-based training program. 

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Understanding the difference between isometric and isotonic exercises can help you determine when to use each in your training. Each of them has its own place in a quality training program and can address various qualities that you would like to improve. 

Isometric exercises involve muscle contractions that do not change the length of the muscle or joint angles. Essentially, you are producing force into an immovable object or resisting motion from an external load.

Compared to exercises that produce changes in muscle length or joint angles, isometric exercises are considered less intense or more basic because they are less dynamic and require less skill to perform.

For example, holding a static squat position will be less complex than a full back squat, as multiple joints move simultaneously to accomplish the repetition.

In general, there is also less muscle damage during isometric versus isotonic exercises that include an eccentric phase, which we will discuss below. (1) 

Since isometric exercises don't include any movement in the actual joints involved in the exercise, you can use them to pinpoint a specific joint angle that may be weak.

For example, if you routinely fail your bench press three inches off your chest but are strong throughout the rest of the range of motion, you can use isometrics to pinpoint and strengthen that joint angle over time.

This is also particularly important if you are rehabbing an injury in the gym, as sometimes you may be unable to move through a full range of motion. By isolating a specific joint angle, you can safely and comfortably train various points in the exercise's range of motion. 

Isometric exercises can help you better control the force you generate with each rep. For example, if you are applying force to an immovable object, the magnitude of that force can be increased or decreased by applying more or less pressure.

Conversely, if you are resisting motion, your force will be directly related to the object's load and what is needed to match the force of gravity.

In isotonic exercise, the force you produce will have to be at least just over the force of gravity to produce concentric motion or under gravity to control the load to the bottom position.

Although there is a degree of control to these, you will have more control over the muscle force you produce with isometrics. 

Anyone can benefit from isometric exercise regardless of whether you are new to the gym or have been training for some time. Different intents, loads, joint angles, and types of isometrics can scale the complexity down or up based on your experience level.

For example, a beginner may opt for isometrics, which involves holding up your body weight against gravity for more extended periods to improve motor control and endurance.

In comparison, a more advanced strength athlete may choose isometric exercises to produce a maximal effort contraction into a load that exceeds their one repetition maximum for short, intense bouts to increase their maximal strength. 

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When prescribing isometrics, there are two categories that you can choose from. These include Yielding Isometrics and Overcoming Isometrics.

Yielding isometrics involves resisting a load against the force of gravity, whereas overcoming isometrics involves producing force into an immovable object. (2)

Generally, yielding isometrics are better suited for building motor control, muscle endurance, and lower-intensity strengthening.

Overcoming isometrics are typically used to produce maximal strength gains and are usually shorter in time than yielding isometrics because of this. 

1. Planks
2. Wall Sit
3. Suit-Case Carries
4. Back Squat Walk Out 

1. Pin Squat
2. Pin Deadlift
3. Pin Bench Press
4. Isometric Knee Extension 

Isotonic exercises involve muscle contractions where there is a change in the length of the muscle as force is applied. These contractions will either cause a lifting or a controlled lowering of an external object or your body weight.

Isotonic contractions that are "concentric" in nature will shorten the muscle where to lift a load from a resting position. Eccentric contractions will cause a lengthening of the target muscle as a load is under control. (3)

Although you can use different techniques to isolate these two types of isotonic contractions, they are present in any exercise where you change the joint angles. (3)

For example, during a back squat, to complete the repetition, you must control the weight down to the bottom position, which is eccentric for the quadriceps (among others), and then to return to the standing position, the quadriceps have to contract concentrically to extend the knees.

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The main benefit of isotonic versus isometric exercises is the functional nature of exercises where joint angles change. Most movements in life and sports involve some sort of muscle contractions where joint angles change, and you are moving, whether moving an external load or the body.

For example, if you had a job that required large amounts of manual labor, such as a construction worker, and needed more strength to lift heavy tools in and out of a truck, building strength in a static position, such as with isometric exercises will only get you so far.

You will need to perform movements under load to strengthen the entire range of motion to accomplish the tasks with as little effort as possible.

But, a common saying is that strength is built in the range it is trained," meaning that you also need to fortify the entire movement to prevent weak points throughout the range of motion that could lead to injury down the road. 

Isotonic exercises can also improve joint mobility over time, with the added benefits of building strength and stability. (4) The ability of your joints to move through a full range of motion depends on both stability and mobility components.

Your joints first need to have enough passive range of motion to have the entire movement available to them. But your joints will also need stability and control to access that range of motion under your power.

Isotonic exercises can improve both of these over time. Current research shows that eccentric-focused exercise can affect muscle length similarly to stretching. (4) As the muscle lengthens under load, the body develops a longer fascicle length or muscle fiber length effectively lengthen the muscle over time. (4)

However, unlike passive stretching, eccentric exercise also helps build strength and stability within the newly acquired range of motion. With the combination of improved range and stability, the improvements you make in your mobility will last longer. 

Building muscle mass ultimately comes down to maximizing muscle tension and damage to stimulate your body to repair and build new muscle tissue. (1)

When comparing isometric and isotonic exercises regarding building muscle mass, isotonic exercise creates more muscle damage than isometric. (1) This is because of the eccentric component of isotonic movements. (1)

Since the muscle must contract while also lengthening under a load, a large amount of muscle damage occurs with each repetition during the eccentric portion of isotonic movements. This may sound like a bad thing, but ultimately, it is what you want if your goal is to maximize your muscle gains.

Once you have created enough muscle damage and tension to stimulate protein synthesis, the muscle building process will begin. When combined with a great diet and the help of high quality protein supplement like MuscleTech’s Grass Fed 100% Whey Protein you can maximize your muscle growth with isotonic training

1. Push-Up
2. Back Squat
3. Walking Lunge 

1. Power Clean
2. Power Snatch
3. Push Jerk 

1. Tempo Back Squats
2. Tempo Bench Press
3. Tempo Romanian Deadlifts 

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References: 

1. Stožer, A., Vodopivc, P., & Križančić Bombek, L. (2020). Pathophysiology of exercise-induced muscle damage and its structural, functional, metabolic, and clinical consequences. Physiological research, 69(4), 565–598. https://doi.org/10.33549/physiolres.934371
2. Schaefer, L. V., & Bittmann, F. N. (2017). Are there two forms of isometric muscle action? Results of the experimental study support a distinction between a holding and a pushing isometric muscle function. BMC sports science, medicine & rehabilitation, 9, 11. https://doi.org/10.1186/s13102-017-0075-z
3. Padulo, J., Laffaye, G., & Chamari, K. (2013). Concentric and eccentric: muscle contraction or exercise?. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 32(11), 2047–2048. https://doi.org/10.7863/ultra.32.11.2047
4. Alizadeh, S., Daneshjoo, A., Zahiri, A., Anvar, S. H., Goudini, R., Hicks, J. P., Konrad, A., & Behm, D. G. (2023). Resistance Training Induces Improvements in Range of Motion: A Systematic Review and Meta-Analysis. Sports medicine (Auckland, N.Z.), 53(3), 707–722. https://doi.org/10.1007/s40279-022-01804-x