Isometric muscle contraction causes increased muscle force due to greater recruitment and increased firing rate at that given joint angle. Isometric exercise can be performed in two ways.

Isometric contraction occurs without movement, like a plank, or a pause during an exercise, like a squat and hold; this places muscles under tension without shortening or lengthening.

Isometric Muscle Contraction: A type of muscle contraction in which activation of motor units and the production of force does not result in joint motion or a change in muscle length. This occurs ...

But after the isometric contraction of the stretched muscle, you perform an additional contraction of the muscle group opposing the muscle being stretched (referred to as the "agonist" muscle ...

Isometric abdominal training (IAT) involves a series of abdominal contractions performed in a static position and free from changes in joint angles.