Which type of muscle action occurs when there is no movement?

Isometric action occurs when there is tension in the muscles without any change in muscle length or joint angle, resulting in no movement at the joint. This type of muscle action is commonly observed when holding a position, such as maintaining a plank position or pushing against an immovable object.

In contrast, eccentric action involves lengthening of the muscle as it contracts, dynamic action includes movement through a range of motion (both concentric and eccentric), and concentric action refers to muscle shortening while generating force. Given that the question specifically asks for the type of muscle action characterized by the absence of movement, isometric action is the appropriate response. This understanding helps to highlight the significance of stability and control in various fitness activities.