Which statement correctly describes eccentric muscle contractions?

• A. They cause muscle lengthening under tension
• B. They cause muscle shortening under tension
• C. They require no nervous input
• D. They occur only during isometric holds

Answer: (A)

Eccentric contractions occur when a muscle is actively producing force while it lengthens under load. This happens when you control or resist a movement, such as slowly lowering a dumbbell in a curl, so the muscle length increases even though it’s actively contracting. This is different from shortening under tension (concentric) and from holding a position with no length change (isometric). Neural input is required to generate that active force during lengthening, not absent. Eccentric actions are key for controlling descent and absorbing impact, and they can produce high forces with relatively lower energy cost compared to concentric actions.