Which contraction maintains a constant speed of movement through the range?

• A. Isokinetic
• B. Isometric
• C. Isotonic
• D. Isotoner

Answer: (A)

The key idea is moving a limb at a steady speed throughout the entire range of motion. An isokinetic contraction is designed to do exactly that: the limb travels at a constant angular velocity, with a machine (an isokinetic dynamometer) adjusting resistance to keep speed steady even as the effort required changes. Because the speed stays the same while the force output can vary, this type of contraction is uniquely suited to maintain constant movement speed across the range.

In contrast, an isometric contraction involves no joint movement at all, so speed is zero. An isotonic contraction involves movement with a relatively constant resistance, but the speed is not guaranteed to remain constant across the range due to changing leverage and muscle mechanics. The other term isn’t used to describe a real motor pattern in this context.