Isometric vs. Isotonic Exercises: What’s the Difference?

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istock_000016880067xsmallThere are a variety of ways to build strength. For example, you can use machines, hand weights, resistance bands, kettlebells, or even your own body weight. In general, strength training exercises fall into two main categories: isometric and isotonic. Do you know the difference?

What Are Isometric Exercises?

Isometric exercises are strength-training exercises that don’t involve joint movement. An example of an isometric exercise is a plank where you hold a position against resistance for a minute or two. Another example is holding a push-up position at the halfway point without moving or pushing against a firm wall with your arms straight. In all of these cases, the joint angle remains fixed, and strength is built by holding a position against gravity or against a fixed resistance such as a wall.

What about Isotonic Exercises?

Isotonic exercises are more dynamic exercises that require a change in muscle length and joint angle. Overhead press, biceps curl, lunges, squats and bench press where muscles and joints change position are just a few examples of isotonic exercises. They’re the most popular type of strength training movements and the ones you see most people doing at the gym.

Isometric vs. Isotonic Exercises: Is One More Beneficial Than the Other?

Most of the focus these days is on isotonic exercises, but isometrics still have their place in a well-rounded fitness program. One way to make them a part of your weight training program is by doing “holds” where you hold the weight against resistance for five to ten seconds before lowering it. For example, when doing biceps curls, lower the weight only half-way, and hold it as long as you can in that position before lowering it in a controlled manner.

There are some disadvantages to isometric exercises over isotonic ones. Isometric exercises increase strength only at a single joint angle, whereas isotonic exercises strengthen muscles throughout the full range of motion of the exercise. You would have to do multiple isometric exercises at different joint angles to get the benefits that a single isotonic exercise gives you.

Another disadvantage of isometric exercises is they can trigger sharp rises in blood pressure and place more stress on the cardiovascular system. They may not be suitable for people with high blood pressure or heart disease. On the plus side, they require no equipment, and you can do them almost anywhere. They’re great for slipping in a quick workout when you don’t have access to any equipment.

The Bottom Line?

The mainstay of your strength training program should be isotonic exercises using bands or weights, but challenge your muscles in a way it may not be accustomed to by adding some isometric holds. This new stimulus can lead to greater gains in strength and lean body mass. In addition, isometric exercises such as planks are one of the best ways to target muscles in your core. For a well-rounded workout, do both isometric and isotonic exercises.

References:
Exercise Physiology. Theory and Application to Fitness and Performance. Seventh edition. 2009.

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