During which type of muscle action does muscle tension remain constant?

Muscle tension remains constant during isometric muscle actions, which is why this choice is the correct answer. In an isometric contraction, the muscle generates force without changing its length, meaning that while the muscle is active and maintains tension, there is no visible movement at the joint. This type of contraction is commonly utilized in exercises aimed at stabilizing joints, such as planks or wall sits, where muscle strength is developed without the muscles shortening or lengthening.

On the other hand, concentric actions involve muscle shortening while generating force, and eccentric actions involve muscle lengthening under tension. Dynamic actions refer to movements that involve both concentric and eccentric contractions, leading to changes in muscle length and joint position. Thus, those types of muscle actions do not maintain constant tension in the same way that isometric contractions do.