What statement best describes isotonic exercise?

What statement best describes isotonic exercise?

• A. Slow, controlled breathing exercises
• B. Muscle shortening and active movement
• C. Muscle contraction without shortening
• D. Muscle contraction with resistance

Answer: (B)

Isotonic exercise is defined by dynamic movement in which the muscle changes length as it contracts, producing joint motion. The essential idea is muscle shortening during the lifting phase (concentric contraction) and often lengthening as you lower the load (eccentric contraction). This describes actions like lifting a dumbbell or performing a squat, where the joint moves through a range of motion. Other options describe different types of muscle action—holding a position without movement is isometric, and simply applying resistance without specifying movement length doesn’t capture the core feature of isotonic activity.

Isotonic exercise is defined by dynamic movement in which the muscle changes length as it contracts, producing joint motion. The essential idea is muscle shortening during the lifting phase (concentric contraction) and often lengthening as you lower the load (eccentric contraction). This describes actions like lifting a dumbbell or performing a squat, where the joint moves through a range of motion. Other options describe different types of muscle action—holding a position without movement is isometric, and simply applying resistance without specifying movement length doesn’t capture the core feature of isotonic activity.