Which activity provides a classic example of an isometric exercise?

Which activity provides a classic example of an isometric exercise?

• A. Bicep curl
• B. Holding a plank
• C. Running
• D. Jumping

Answer: (B)

Isometric exercise means the muscle contracts to produce force without changing length and without moving the joint. Holding a plank does just that: you brace the core, glutes, shoulders, and legs to keep your body in a straight line, so the muscles stay contracted while the joints stay still. In contrast, a bicep curl changes the elbow angle as you lift, which lengthens and shortens the muscle (an isotonic movement). Running and jumping involve dynamic movement with joints bending and muscles changing length, not static contraction. So holding a plank is the classic example of an isometric exercise.

Isometric exercise means the muscle contracts to produce force without changing length and without moving the joint. Holding a plank does just that: you brace the core, glutes, shoulders, and legs to keep your body in a straight line, so the muscles stay contracted while the joints stay still. In contrast, a bicep curl changes the elbow angle as you lift, which lengthens and shortens the muscle (an isotonic movement). Running and jumping involve dynamic movement with joints bending and muscles changing length, not static contraction. So holding a plank is the classic example of an isometric exercise.