What defines a "pump or rotation" in pitching terms?

In pitching terminology, the concept of "pump or rotation" typically refers to a dynamic motion where the pitcher's arms alternate in a coordinated fashion, moving up and down. This action is essential as it helps generate momentum and prepares the pitcher for a more powerful and effective delivery. By incorporating both upward and downward motions, pitchers can optimize their arm speed and enhance their overall pitch mechanics, leading to better accuracy and velocity.

The other options describe various aspects of pitching mechanics but do not accurately capture the essence of what a "pump or rotation" entails. The downward motion of the arm before release represents part of a pitcher's delivery but lacks the emphasis on the alternating motion. Similarly, the idea of legs moving prior to pitching focuses on a different aspect of the pitching motion, while the circular arm movement may refer to other pitching styles that do not align with the definition of a pump or rotation. The correct answer encapsulates the key characteristic of alternating arm movements that define this concept in pitching.