An isometric muscle contraction, or static exercise, is one in which the muscle fires but there is no movement at a joint. In this type of muscle contraction, there is no change in length of the muscle, and no movement at the joints but muscle fibers fire. An example of isometric exercise includes pushing against a wall.
The benefit of isometric exercises are that they can be used for rehabilitation as well as general strengthening without placing stress on the joints.
Some sports require a high level of static muscle strength. Gymnastics, yoga, rock climbing, and downhill skiing, for example, all have static strength requirements.