What muscle is the woman using to lift the ball over her head

Deltoid

Explanation:

The muscles of the trunk and the muscles of the lower extremity will be used for stability and moving the box across the 2 meters. The muscles of the upper extremity would be used to varying degrees to lift, hold, and lift the box to sternum level and place it in its place and which muscles contribute to the specific portion of the task you intend to study will depend on the magnitude of the load, the frequency the task is completed, the velocity at which the task is completed, the height differential between where the box is lifted from to the height at which the box is placed when the task is completed.