Isometric exercises are movements involving isometric contraction. There are three types of muscle contractions:

* Concentric

* Eccentric

· Isometric

With a concentric movement, the muscle shortens during work, as in the flexion phase of the biceps. On the contrary, the eccentric movement lengthens the muscles during work, as the phase of lowering the flexion of the arms on the biceps.

But isometric exercises require you to exert muscle strength without moving. In other words, you have to hold the contraction without moving in the joint.
When you contract a muscle isometrically, you do not move the limbs, do not lengthen or shorten the muscle fibers — the joint is considered static. Even if you don't move the mouse within its range of motion, the fibers are still activated and excited in response to resistance.