Isokinetic, Isotonic, and Isometric Exercises
Aerobic exercise and strength training are both beneficial for one’s health and well-being. When it comes to strength training, also called resistance training, it can be practiced in three different ways or in combination: isokinetic exercises, isotonic exercises, and isometric exercises.
All three words have Greek roots, with the first, isokinetic, meaning “same speed.” Isokinetic exercises involve specialized machines to keep the muscles moving at a constant speed. The equipment used for isokinetic training is an isokinetic dynamometer, and the average person typically will not practice with one. This type of workout assesses muscle function of people with specific injuries and athletes, as well as helps athletes learn to use their maximum strength at higher speeds. For instance, a baseball pitcher may perform isokinetic exercises to improve their throwing.
Isotonic means “same tension,” and isotonic exercises involve moving your joints through a full range of motion while there is a constant amount of tension or weight against your muscles. A typical example of an isotonic exercise is the bench-press, where the weight remains the same while the arms’ joints start out bent and straighten completely. Squats and push-ups are also isotonic exercises, in which you use your body weight while moving the joints through their full range of motion — in this case, the knees for squats and the elbows for push-ups.
Widely performed in gyms, isotonic exercises help strengthen and build muscles and build up bone density, as well as improve blood sugar regulation. Two movement patterns typically seen during an isotonic exercise are concentric and eccentric movements. During a concentric movement, the tension is placed on a muscle that is shortening, while eccentric movement places tension on a muscle that is lengthening. With concentric and eccentric exercises, muscle fibers break down and, while resting, they are repaired and end up stronger than before.
The third form of strength training is the isometric exercise, where isometric means “same length.” This type of low-impact activity involves straining the muscles statically — without moving or bending any joints. Isometric exercises exert tension and engage the muscles but do not lengthen or shorten them. A notable example of isometric exercise is holding the body in a plank position — the top of a push-up without bending the elbows while contracting and engaging the core. Wall sits, glute bridges, and many yoga poses are also isometric exercises.
Isometric exercises are highly recommended to tone the muscles, maintain strength, and maintain muscular endurance, or the ability to contract a muscle for an extended period. People recovering from surgery and people with rheumatoid arthritis, for example, find isometrics especially useful because they are low impact and can target areas that need strengthening without straining injured or weak joints. However, although isometric exercises are highly effective in maintaining stability and strength, they have limits when building stronger muscles.
When possible, isometrics can be incorporated into isotonic exercises. For example, in a squat, a mostly isotonic exercise, an isometric phase can be added between the eccentric phase, when you lower the weight and lengthen the muscles, and the concentric phase, when you push the weight up, contracting the muscles. In this case, you can pause at the bottom and hold the position for a few seconds.
