In an isometric muscle exercise, the joints are:

In an isometric muscle exercise, the peculiarity lies in the fact that the muscles are contracted, but there is no change in muscle length or joint angle. This means that while the muscles are actively engaged, they do not produce movement at the joints. The contraction happens without any visible movement, which is a hallmark of isometric exercises.

For instance, if you're pushing against a wall or holding a weight in a fixed position, your muscles are exerting force and developing tension, but the joints remain in a stationary position. This is in contrast to isotonic exercises, where the muscles change length and joints move.

Understanding this principle is fundamental in exercise physiology and rehabilitation. Isometric exercises are often utilized for building strength, stability, and endurance without placing stress on the joints, making them particularly useful in certain therapeutic settings.