If you've ever come across the term "isotonic exercise", and you're not sure what it means or what type of exercises it's referring to, you're in the right place.
This is what we're going to explain in this post. We'll quickly break down what an isotonic exercise is and why it's worth knowing, before moving on to some of the best examples of isotonic exercises for you to add to your workout routine.
What are Isotonic Exercises?
An isotonic exercise is one where your muscles are placed under a certain amount of tension, which remains the same as the muscle contracts and goes through a full range of motion.
The word "isotonic" derives from Greek, "iso" meaning "same" and "tonic" meaning "tension". This term "same tension" gives the explanation of what an isotonic exercise entails.
To put it into more practical terms, an isotonic exercise is any kind of exercise where the muscle contracts, and the resistance (this could be a weight, such as a barbell or dumbell, your bodyweight, or a resistance band) remains the same throughout the movement.
What are the Two Forms of Isotonic Exercise?
Within an isotonic exercise, there are two different types of muscle contraction that take place - concentric muscle contraction and eccentric muscle contraction.
Most isotonic training will involve both forms of muscle contraction, though it's possible to only have one.
Let's take a quick look at these two ways that muscles contract now.
Concentric Muscle Contraction
Concentric muscle contraction is when a muscle shortens. If we take the example of a bicep curl, this is the "up" part of the movement, where you raise the weight and the bicep muscle becomes shorter.
Eccentric Muscle Contraction
Eccentric muscle contraction is when the muscle lengthens under resistance. Using the same example of a bicep curl, the eccentric part of the movement is the "down" part, where the weight is lowered back to the starting position.
Generally speaking, concentric exercises are better for building strength and power, whereas eccentric exercises are better for hypertrophy (i.e. muscle growth).
In most cases, isotonic movements include both concentric and eccentric contraction - you'll lift a weight and lower it again. It's important to consider this as you do the movement, in order to get the full benefit for both strength and hypertrophy.
7 Examples of Isotonic Exercises
Want some clear examples of isotonic exercises? No problem.
We simply couldn't list every isotonic exercise there is, because isotonic training covers a massive range of movements and exercises. But to give you an idea, here are seven of the most popular, along with their benefits and the muscles worked.
Bicep Curls
A bicep curl is probably the clearest example of an isotonic movement.
In this exercise, you lift a weight (usually a dumbell) from a stationary position by your sides, up towards your shoulder, before lowering it back to the starting position. Doing so contracts your bicep muscle through both concentric and eccentric contractions.
Muscles targeted:
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Biceps
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Deltoid
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Forearms
Squat
Squats are another great isometric exercise example, working all the major muscle groups in the lower body.
There are many variations of the squat, and different ways to do a squat, including weighted or unweighted.
The classic squat starts with feet shoulder-width apart, with a weight loaded on your shoulders (or no weight, for a bodyweight squat). Bend your knees and lower your center of gravity down, until your knees are at around a 90 degree angle, and then push with your feet back into the starting position.
Muscles targeted:
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Quads
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Hamstrings
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Glutes
Bench Press
Bench presses are a traditional exercise for the upper body, specifically the chest. In this exercise you'll contract the pectorals in an isotonic movement, while also working a few surrounding muscle groups.
Bench press is usually done on a flat bench, with a barbell or two dumbbells (one in each hand). Variations include inclined or declined bench presses, but all are examples of isotonic exercise.
Muscles targeted:
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Pectorals
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Anterior deltoids
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Triceps
Push Ups
The push up is more or less the same movement as a bench press, only facing towards the ground, starting in a plank position. As push ups are often done unweighted (with only your body weight putting tension on the muscles), they can be a great alternative isotonic exercise to the bench press for beginners.
Muscles targeted:
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Pectorals
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Triceps
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Anterior deltoids
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Core
Pull Ups
Pull ups are one of the best isotonic exercises for the back, and all-round upper body strength. You grip an overhead bar with your hands facing away from you and pull your body up until your chin is over the bar.
Pay attention to lower your body slowly, keeping tension the whole way, which will give you both the concentric and eccentric muscle contractions in each rep.
Muscles targeted:
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Latissimus dorsi
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Traps
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Rhomboids
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Biceps
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Triceps
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Stabilizer muscles & core
Crunches
A crunch is an isotonic exercise that primarily targets the abdominal muscles. To do a crunch, lie on your back on a mat with your knees bent and your feet flat on the floor. Use your abdominal muscles to curl your upper body up towards your knees, keeping your lower back pressed into the mat throughout the entire movement. Hold for a second at the top of the crunch, hold for a second, then slowly lower back down to the starting position.
Muscles targeted:
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Abdominal muscles
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Obliques
Running
Even aerobic exercises like running are great examples of isotonic exercise. It makes sense if you think about it - your muscles contract as you run (primarily those in the lower body), and you have the same tension on your muscles the whole way through (body weight/the weight of gravity).
Along with running, other aerobic exercises like swimming, skiing, dancing, and even everyday household activities can be considered to be isotonic exercises.
Muscles targeted:
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Glutes
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Quadriceps
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Hamstrings
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Calves
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Core
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Hip Flexors
What are the Benefits of Isotonic Exercises?
Isotonic exercises have a ton of benefits, which is why they make up the core of most workout routines. These benefits include:
Stronger muscles
Isotonic exercises are great for strength training. Contracting your muscles under resistance, whether that's a weight, resistance band, bodyweight or anything else, trains your muscles to be able to withstand higher resistance and generate more power, thus getting stronger.
Increased muscle mass
Resistance training exercises are also great for building bigger muscles. The muscle tension stimulates hypertrophy, which is when muscle fibers undergo a number of tiny tears, and are rebuilt (with adequate protein intake and rest) bigger and stronger.
Stronger bones
Putting your body under resistance, such as from heavy weights, improves bone density. Higher bone density means lower likelihood of broken bones, and less risk of conditions like osteoporosis later in life.
Better cardiovascular health
Isotonic exercise requires increased cardiovascular output, in order to pump oxygen to the muscles used in the movement. This is great for your cardiovascular system, and over time leads to a more healthy heart, lower blood pressure and less risk of cardiovascular-related diseases.
Functional strength and mobility
The range of motion from isotonic exercises is a great way to build functional strength and mobility, which benefits you in a lot more areas, including other sports and physical activities, along with increased wellbeing in everyday life.
Weight loss
Isotonic exercises and resistance training require a significant calorie output, which is great for burning unwanted fat and losing weight. Resistance training also stimulates a metabolic response, boosting the rate at which your body passively burns calories and thus further improving fat/weight loss.
Convenience
Isotonic exercises can be done in a wide range of different settings, with whatever equipment you have available. All you need is a bit of space and something heavy that's going to place tension on your muscles.
Even if you don't have a heavy object, you can do isotonic exercises simply with your body weight (and with a little help from gravity).
Isotonic vs. Isometric Exercises
The majority of exercises you'll do in the gym are isotonic exercises. But you may also incorporate another form of exercise, called isometric exercise, into your routine.
Isometric exercises also get their name from ancient Greek. The term "isometric" means "same length", meaning the muscles don't change length throughout the movement, unlike an isotonic exercise.
Isometric exercises are stationary exercises, such as a plank or wall sit, where isometric muscle contraction takes place while the length of the muscle stays the same, and the joints don't move. Many yoga poses are also great examples of isometric exercise.
As for comparing isotonic vs isometric training, both can be effective. Generally, isotonic exercise is more effective, particularly for muscle mass, strength, power, and cardiovascular health.
Isometric exercises, on the other hand, are good for muscle tone and muscular endurance, and also provide some benefits for strength and size. They're also safer, and better for people recovering from injuries or as part of physical therapy, as there's less risk of overloading the muscles and/or joints.
There's no need to restrict yourself to one, though. You can fit both isotonic and isometric exercise into your workout routine easily, and get all the benefits of both.
Who Should Perform Isotonic Exercises?
Everyone should do some form of regular isotonic exercise.
Isotonic exercise is great for athletes or those who want to improve their performance in sports or other physical activities.
Isotonic exercise is also ideal for improving muscle strength and/or aesthetics, which is why the majority of strength training features isotonic exercise.
Even if you're not an athlete, and not concerned too much with your appearance, isotonic exercise can help you live healthier and avoid health conditions, such as cardiovascular issues or low bone density in later life.
Sample Beginner's Isotonic Workout
There's no shortage of ways to start working out with isotonic exercises.
All you need to know is:
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You need to put your muscles under some form of resistance
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Keep the tension constant as the muscles contract
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Put the joint/muscle through a safe, yet full range of motion
A beginner could start with a full-body workout like this.
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Exercise 1 (back): pull-ups
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Exercise 2 (chest): push-ups
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Exercise 3 (biceps): bicep curls
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Exercise 4 (triceps): tricep extension
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Exercise 5 (lower body): squats
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Exercise 6 (core): crunches
Take a few days to rest between each workout, and be sure to get the right nutrition to support performance and recovery, such as a daily protein shake.
