ABSTRACT
Pushing is the act of applying a muscular force in a direction away from the body; pulling is the opposite. Directions oblique to the trunk may be regarded as push or pull depending on the direction of the resultant force. In some cases the distinction between a pull and a lift may not be clear, as when extending the arm in front the body and gripping and raising an object from below the shoulder. A pull is almost always characterized by grasping the object, except in rare cases as when using a hook grip. A push may be applied with or without a grasp, as when the palmar surface of the open hand and fingers makes contact with the wall of a large box. The hand-handle contacts during pushing or pulling vary considerably but, for convenience, they may be classified into three main types: (i) full-hand power grasping, (ii) finger pinch grasping, and (iii) flat hand contact.
