Which muscle action produces tension while lengthening?

• A. Concentric
• B. Eccentric
• C. Isometric
• D. Stabilizer

Answer: (B)

This question tests how a muscle can generate force while lengthening, which is known as an eccentric contraction. In an eccentric contraction, the muscle develops tension as its fibers lengthen under an external load. You can feel this during the controlled lowering phase of a squat or when lowering any weight slowly—the muscle is actively resisting the descent, but its length increases.

In contrast, a concentric contraction is when the muscle shortens while producing force (like lifting a weight). An isometric contraction produces tension without any change in length (holding a position still). A stabilizer helps keep joints steady and alignment correct, often with static tension rather than a primary movement, so it doesn’t describe the length-change aspect of the contraction.

So, the scenario described—tension produced while the muscle lengthens—points to eccentric action.