Isometric Vs Isotonic Exercise: Which Is Better For Your Training?

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One of the best things about exercise is that there are so many types to choose from. However, with such an extensive Rolodex of options, it can be difficult to know which types of exercise you should be doing for different purposes and goals.

From cardio exercises like cycling or rowing to strength training and flexibility exercises like yoga, there can be an overwhelming array of types of exercises and workouts to balance your fitness routine.

And then there are the types of exercises you’ve heard of once or twice but really know little about. Examples include isometric exercises and isotonic exercises.

Although both isotonic and isometric exercises are probably types of exercise you are familiar with in practice, there’s a good chance that you are not sure what the differences are between isometric vs isotonic exercise, and you might not know what specific exercises qualify as isometric vs isotonic exercises.

In this article, we will discuss isometric vs isotonic exercises, from the basic definitions to a more detailed discussion of how to do isometric vs isotonic exercises and why each one is important.

We will cover: 

  • What Is Isometric Exercise?
  • What Is Isotonic Exercise?
  • Differences Between Isometric vs Isotonic Exercises
  • Benefits Of Isometric vs Isotonic Exercise
  • Should You Do Isometric Exercises or Isotonic Exercises?

Let’s get started!

A class of people doing side planks.

What Is Isometric Exercise?

Even if you’ve been working out regularly for years, there’s a decent chance that you haven’t heard the term “isometric exercise,” as it’s not a term commonly used in the vernacular in fitness routines of everyday gym goers.

That said, most strength training routines usually include at least one or two isometric exercises.

Therefore, let’s start with a basic definition of isometric exercise.

The prefix “iso–“ means “same.” For example, a plank is considered an “isometric“ exercise because the prefix “iso-“ means “same” and the suffix “-metric“ means length, and in the plank exercise, the muscles are not contracting to shorten or lengthen to stretch, so they are remaining the same length throughout the exercise.

Therefore, isometric exercises are exercises that require your muscles to contract without actually generating movement in your body.

Essentially, an isometric exercise is a static hold. Your muscles are still doing work, but no joint movement is occurring.

Examples of common isometric exercises include forearm planks, high planks, side planks, wall sits, the top position of a glute bridge if you hold your hips up for several breaths, and holding the lower position of a push-up with your chest hovering just over the ground. 

People doing renegade rows.

What Is Isotonic Exercise?

Although even most avid gym goers are unfamiliar with the technical term “isotonic exercise,“ the majority of the strength training exercises you typically perform are considered isotonic exercises.

With isotonic exercises, the “iso-“ prefix refers to “same,” and the suffix “-tonic” refers to tension.

Therefore, isotonic exercises are those in which the resistance remains constant, so the amount of tension in the muscle remains the same while the muscle shortens (referred to a concentric muscle contraction) and lengthens (eccentric contraction) throughout the range of motion of the movement.

Pretty much all of the standard strength training exercises you do—such as biceps curls, squats, deadlifts, rows, overhead presses, and triceps extensions—are isotonic exercises.

Differences Between Isometric vs isotonic Exercises

Now that we’ve covered the basic definitions of isometric exercises and isotonic exercises, it’s easier to understand the differences between isometric vs isotonic exercise.

To summarize, the primary difference between isometric vs isotonic exercise is that in isometric exercise, there is no movement that takes place, whereas in isotonic exercise, the muscles are shortening and lengthening throughout the range of motion to move a joint.

Due to these differences, the benefits of isometric vs isotonic exercise are a bit different.

A class of people doing squats.

Benefits of Isometric vs Isotonic Exercise

Both types of exercise have the primary goal of strengthening your muscles

With that said, isometric exercises are particularly low-impact exercises because no movement is occurring at your joints. This makes isometric exercise particularly safe for those with joint pain or arthritis and people recovering from an injury.

Isometric exercises also lend themselves well to increasing muscular endurance because you can simply increase the length of time that you hold each exercise.

Isometric exercises also help build stability. Stability around your joints is as important as mobility

Your muscles need to be able to control allowable movement in order to aid balance, prevent falls, and provide a stable base of support while other parts of your body move.

There are health benefits of isometric exercises as well.

A person doing a squat.

As long as you are breathing properly throughout the movement, isometric exercises can also be beneficial for people who have hypertension or are at a high risk of heart disease.

For example, studies have shown that regularly performing isometric exercises can lower systolic blood pressure by 7 mmHg regardless of whether you have hypertension or normal blood pressure.

This is not to say that isotonic exercises do not also have the potential to lower your blood pressure and reduce your risk of heart disease.

However, it is worth mentioning this benefit with isometric exercises because we previously believed that static holds could increase blood pressure and would therefore be unsuitable for those at a higher risk for adverse cardiovascular events.

Another benefit of isometric exercises vs isotonic exercises is that most isometric exercises do not require any exercise equipment, while most—but not all—isotonic exercises do.

A person doing a kettle bell press.

Benefits of Isotonic vs Isometric Exercise

On the other hand, one of the benefits of isotonic vs isometric exercise is that the movement component inherent in isotonic exercises helps improve joint mobility and flexibility much more so than isometric exercise. 

Having full range of motion in your joints helps preserve optimal functioning, reduces pain and stiffness, and improves athletic performance.

It’s also generally easier to build strength and muscle mass through isotonic exercises because you can increase the external load by using resistance training equipment such as dumbbells, resistance bands, kettlebells, weight machines, etc. 

Thus, it’s easier to overload your muscles (appropriately), which is necessary to stimulate muscle growth and increase strength.

With isometric exercises, it can be more challenging to effectively follow the principles of progressive overload, which are necessary to continually adapt without hitting plateaus in your strength and body composition.

Although not unilaterally true, another benefit of isotonic exercises vs. isometric exercises is that isotonic exercises tend to burn more calories. You are typically generating higher forces and moving your body, which is more energy-demanding than holding a static posture.

People doing side planks, an isometric exercise.

This can make isotonic exercises particularly beneficial for people who are trying to lose weight through strength training.

There are also health benefits associated with isotonic exercises, but it’s unclear whether these same benefits can be gleaned from performing isometric exercises but just haven’t been studied in as much depth due to the higher prevalence of isotonic exercises in most resistance training routines.

With that said, one large correlational study of women found that those who routinely engaged in regular strength training had a 30% lower risk of type 2 diabetes and a 17% reduced risk of cardiovascular disease compared to age-matched peers who did not habitually strength train.

Several other studies have found that individuals who regularly perform isotonic exercises and a well-rounded strength training program have a higher bone mass and higher bone density than individuals who do not.

Because low bone density can lead to osteoporosis and is associated with an increased risk of fractures, this is an important benefit of isotonic exercises for all adults, especially women, as bone mineral density has been shown to decrease significantly after menopause.

People working out in a gym.

Should You Do Isometric Exercises or Isotonic Exercises?

Ultimately, for most people, it’s best to do a combination of isometric and isotonic exercises in a well-rounded, total-body strength training program.

This will ensure you get the benefits of both types of exercise.

Both types of exercise can strengthen your muscles, and you’ll improve stability and balance with isometric exercises in a low-impact, joint-friendly manner, while you will increase muscle strength, size, mobility, flexibility, and metabolic rate with isotonic exercises.

With both isometric and isotonic exercises, remember to increase the difficulty of the exercise as you get stronger by increasing the weight used or load (with isotonic exercises) or adding load with isometric exercises by holding a weight for exercises like squat holds or wearing a weighted vest for planks.

You can also increase the duration of isometric exercises and the number of reps and sets for isotonic exercises.

Vary the specific exercises you do to keep your body constantly adapting and progressing. For a list of compound exercises to add to your strength training program, check out our Complete List of Compound Exercises.

A person doing a plank in the grass.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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