Which statement accurately describes isotonic and isometric contractions, with examples?

• A. Isotonic contractions change muscle length with constant tension (concentric or eccentric); isotonic examples include lifting a dumbbell or lowering it slowly; isometric contractions generate force without changing length.
• B. Isotonic contractions generate force without changing length; isometric contractions shorten the muscle.
• C. Isometric contractions involve lengthening while under tension; isotonic contractions involve no change in length.
• D. Isotonic contractions only occur in cardiac muscle; isometric only in skeletal muscle.

Answer: (A)