What is an example of an isometric contraction?

An isometric contraction occurs when a muscle generates tension without changing its length, meaning there is no visible movement at the joint. In this context, holding a plank position provides a clear illustration of an isometric contraction, as the muscles must remain engaged and contracted to maintain the position, yet there is no movement occurring; the body remains stationary.

In contrast, lowering a dumbbell in a bicep curl involves eccentric contraction, where the muscle lengthens while still under tension. Lifting a weight off the ground involves concentric contraction, where the muscle shortens as it generates force to lift the weight. Stretching a muscle doesn't involve contraction in a traditional sense but rather elongation, which also does not fit the definition of an isometric contraction.