Isotonic exercises are?

• A. Exercises that increase muscle tension without shortening or actively moving the muscle.
• B. Exercises that cause muscle contraction and change in muscle length.
• C. Breathing exercises to improve oxygenation.
• D. Stretching without movement.

Answer: (B)

Isotonic exercises involve contracting a muscle while it changes length and moves a joint. When you lift, push, or bend, the muscle shortens during the lifting phase (concentric contraction) and may lengthen during lowering (eccentric contraction). The key idea is movement with a change in muscle length against resistance. This differs from isometric exercise, where tension is produced without length change or movement, and from stretching with no active movement. Breathing exercises don’t center on muscle length changes.