Isometric exercise

Isometric exercise or isometrics are a type of strength training in which the joint angle and muscle length do not change during contraction (compared to concentric or eccentric contractions, called dynamic/isotonic movements). Isometrics are done in static positions, rather than being dynamic through a range of motion.

In an overcoming isometric, the joint and muscle work against an immovable object. In contrast, in a yielding isometric, the joint and muscle are held in a static position while opposed by resistance.

In the context of the bench press, an example of a yielding isometric would be holding the bar at a given place even though it could be pressed higher, and an overcoming isometric would be pressing the bar up into the safety guards of a squat cage that prevent pushing the bar any higher.

The distinction is that in a yielding isometric, one is pressing roughly the exact amount of pressure needed to negate the resistance, neither dropping or lifting it. Whereas in an overcoming isometric, one can be exerting more force and simply unable to move it. The yielding wavers slightly into concentric and eccentric actions due to inexact control, whereas the overcoming isometric is more purely isometric and can involve more variation in the force used, since one can press harder without the bar moving.

In overcoming isometrics, subjects can safely do 100 percent effort, and continue with 100 percent available effort as strength is depleted, allowing longer time under (maximum volitional) tension. This is thought by experts such as Ken Hutchins and Drew Baye to be best for building muscle. However, subjects depend on a subjective perception of effort and progress, unless a metered system is available.

Yielding isometrics allow measurable progress. Free-weight enthusiasts tend to believe the "back pressure" of real weight is superior for building strength, possibly triggering a productive "fight or flight" response. However, the extremely heavy weights needed by advanced subjects can be an inconvenience, and present a risk of injury.

An isometric exercise is a form of exercise involving the static contraction of a muscle without any visible movement in the angle of the joint. The term "isometric" combines the Greek words "Isos" (equal) and "metria" (measuring), meaning that in these exercises the length of the muscle and the angle of the joint do not change, though contraction strength may be varied. This is in contrast to isotonic contractions, in which the contraction strength does not change, though the muscle length and joint angle do.

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