A simple machine consisting of a larger wheel-like device rotating about a smaller central device called an axle. The radius of the wheel corresponds to the force arm of a lever. When a force is applied to the wheel in order to turn the axle, the mechanical advantage favours force; when the force is applied to the axle in order to turn the wheel, the mechanical advantage favours speed. Most wheel and axle arrangements in the human body, such as the trunk rotating around the vertebral column, favour speed.
Subjects: Sports and Exercise Medicine.