What axis of motion is the push-up done in?

a push up (shoulder horizontal abduction/adduction, elbow flexion/extension, and scapular retraction/protraction) is done around a vertical axes, in the transverse plane, while lying pronated. The axes of motion change relative to the body so a vertical axes will not always be perpendicular to the ground but more importantly traverse through the body from head to toe regardless of the body's relative position to earth.