Here's why:

* Isometric: Means "equal measure". In isometric exercises, the muscle length stays the same. You contract the muscle, but there's no visible movement of the body part.

* Contracted and held: You engage the muscles and maintain tension for a specific duration.

* No body movement: The key is that there is no change in the angle of the joint.

Examples of Isometric Exercises:

* Plank: Engaging core muscles while holding a straight body position.

* Wall Sit: Leaning against a wall with knees bent at a 90-degree angle.

* Isometric Shoulder Press: Pressing your hands against a wall with elbows bent.

* Isometric Bicep Curl: Holding a weight at a 90-degree angle at the elbow.

Important Note: While isometric exercises don't involve movement, they are still effective for building strength and endurance. They can be used as part of a well-rounded fitness program.