Which statement best defines an isometric exercise?

Which statement best defines an isometric exercise?

• A. The muscle length changes through a range of motion.
• B. The joint angle changes constantly during contraction.
• C. The muscle generates force but no joint movement.
• D. The muscle generates force with concentric shortening.

Answer: (C)

Isometric contraction involves generating force without changing the length of the muscle or the angle of the joint. In isometric exercise, you tense the muscle and hold a position against an immovable resistance, so there’s no movement of the joint even though the muscle is working hard. That static, hold-and-stabilize effort is what defines an isometric action. For example, holding a plank or pushing against a wall without moving it uses an isometric contraction—the muscles are firing, but the joint angles stay constant. The other ideas describe dynamic movements: changing muscle length through motion, joints moving during the effort, or the muscle shortening under load (concentric shortening). Those are not isometric contractions.

Isometric contraction involves generating force without changing the length of the muscle or the angle of the joint. In isometric exercise, you tense the muscle and hold a position against an immovable resistance, so there’s no movement of the joint even though the muscle is working hard. That static, hold-and-stabilize effort is what defines an isometric action.

For example, holding a plank or pushing against a wall without moving it uses an isometric contraction—the muscles are firing, but the joint angles stay constant.

The other ideas describe dynamic movements: changing muscle length through motion, joints moving during the effort, or the muscle shortening under load (concentric shortening). Those are not isometric contractions.