What is an example of an isometric contraction?

An isometric contraction occurs when a muscle generates force without changing length. This means that the muscle remains contracted and tense without causing movement in the joint it is associated with. Holding a plank position is an excellent example of this type of contraction. In this exercise, the muscles are activated to maintain a stable position, particularly the core, without any actual joint movement. This stable hold requires muscular endurance and strength, which is characteristic of isometric exercises.

In contrast, activities like weight lifting, running in place, and jump squats involve dynamic movements where the muscles shorten and lengthen, thus representing isotonic contractions instead. These exercises engage muscles through a range of motion rather than holding them in a stationary position, which is why they do not qualify as isometric contractions.