Which statement correctly describes isotonic exercise?

Which statement correctly describes isotonic exercise?

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

Answer: (C)

Isotonic exercise centers on muscle shortening as the limb moves against resistance. The defining feature is active movement with a change in muscle length, including both concentric contractions (shortening) and eccentric contractions (lengthening) as you move through a range of motion. That’s why the statement describing muscle shortening and active movement fits best, with examples like lifting weights, push-ups, or squats. In contrast, isometric efforts involve tension without any change in muscle length (no movement), slow breathing exercises aren’t about muscle shortening with movement, and simply saying a contraction with resistance is too vague and doesn’t specify the essential movement and shortening.

Isotonic exercise centers on muscle shortening as the limb moves against resistance. The defining feature is active movement with a change in muscle length, including both concentric contractions (shortening) and eccentric contractions (lengthening) as you move through a range of motion. That’s why the statement describing muscle shortening and active movement fits best, with examples like lifting weights, push-ups, or squats.

In contrast, isometric efforts involve tension without any change in muscle length (no movement), slow breathing exercises aren’t about muscle shortening with movement, and simply saying a contraction with resistance is too vague and doesn’t specify the essential movement and shortening.