Which type of muscle movement involves no change in muscle length?

• A. Isokinetic
• B. Isotonic
• C. Isometric
• D. Isotoner

Answer: (C)

In isometric contractions, the muscle generates force without changing its length. That means the joint angle stays the same while tension builds, like holding a static position (a plank, a wall push, or holding a weight steady without moving). The muscle is active and tense, but there’s no joint movement.

If you’re moving through a range of motion, the length of the muscle changes, which happens in other types of contractions. Isokinetic involves moving at a constant speed with resistance that adjusts to keep that speed, so length changes as you move. Isotonic involves length changes with movement, typically with a constant external load, so the muscle shortens during lifting and lengthens during lowering. The term that isn’t a real contraction type is the distractor.