The University of California San Diego defines an isometric muscle contraction as a contraction in which the muscle is activated and held at a constant length instead of being allowed to lengthen or shorten. An example of an isometric muscle contraction is carrying a heavy object in front of the body, while the object pulls down, the hands and arms oppose the force but do not move up or down.
According to Healthline, isometric exercises can be used as strength training. Because isometric exercises are done in a static position, which means they do not require dynamic movement, they can be performed anywhere without weights or other equipment. It only takes about 10 seconds to successfully complete one isometric exercise. These qualities make isometric muscle contraction an effective way to add strength training into a busy day.
Healthline suggests a series of effective isometric exercises that can be done throughout the day. The first is a palm press. In this exercise, the palms are pressed together as hard as possible for 10 seconds. A second exercise, the core engagement, is performed while sitting in a chair. The stomach muscles are deliberately tightened and feet are held a few inches above the floor. Isometrics are most effective when incorporated into a larger strength-training program.