Isometric exercise is a form of physical exercise in which the muscles flex and hold a stationary position. No movement of a load takes place, and the exercises require little in the way of equipment. An example of an isometric exercise is placing the palms of the hands against each other and pushing. Isometric exercises are primarily used in physiotherapy and injury rehabilitation because the intensity can be rapidly and precisely adjusted, which makes them very safe. They are now rarely used outside this context. Strength training using isometric exercises was popularised by Charles Atlas from the 1930s onwards.
The term "isometric" combines the prefix "iso" (same) with "metric" (distance), meaning that in these exercises the length of the muscle does not change.
