Isometric exercises are contractions o a very specific muscle or group of muscles. During these types of exercise the muscle doesn’t appear to change in length while the joint involved doesn’t move. Isometric exercise isn’t a particularly effective way of gaining strength, but it will help you to maintain it (this is why it’s often used during rehabilitation processes).
Since these exercises are carried out in a steady position, they’ll only strengthen a particular area. You’d have to do a variety of isometric exercises, using your limb’s entire range of motion, to work out your muscles at different positions. In fact, and due to its static nature, isometric exercise doesn’t improve speed or athletic performance. On the other hand, it can contribute to stabilization (keeping a particular muscle group in the same position) and balance: muscles contract isometrically to enhance stability.
As we mentioned earlier, isometric exercises can also help recover from injury and certain conditions, such as arthritis, which could make movement painful or be aggravated by pulling a joint through the entire range of motion. If you hurt your rotator cuff (the muscles and tendons that stabilize your shoulders, for example, your doctor or physical therapist might suggest isometric exercises to maintain shoulder strength during the recovery stage.
Finally, a recent study has shown that isometric exercises can help lower blood pressure, although this doesn’t mean that you should automatically jump into an isometric training routine, especially if you have high blood pressure. Exercise raises blood pressure, so be sure to talk to your doctor before you start an isometric training program.