An isometric exercise device is a device used to exercise most body parts including the wrist and is often used as part of physical therapy or in order to build muscle strength in a low impact manner.
This is reflected in the name; the term "isometric" combines the prefix "iso" (same) with "metric" (distance), meaning that in these exercises the length of the muscle does not change,[1] as compared to isotonic contractions ("tonos" means "tension" in Greek) in which the contraction strength does not change but the joint angle does.
While isometric training increases strength at the specific joint angles of the exercises performed and additional joint angles to a lesser extent, dynamic exercises increase strength throughout the full range of motion.
These isometric contractions recruit muscle fibers that are often neglected in some dynamic exercises.
For example, gymnasts are extremely strong at great ranges of motion through the practice of isometric holds.