The cable pullover is a great way to work the upper back muscles. This exercise also works just about all the muscles of the upper body to some degree. The largest muscle in the back is scientifically known as the latissimus dorsi. You might see it referred to as the "lats" or "wings." The lats are used any time you pull something. For example, when you open a fridge or a car door, you are primarily using your lat muscles.
First, ensure the cable pulley unit is about a foot higher than the location your head will be during the exercise. Next, lie down on a workout ball. Try to position the ball on your upper back. Grab a cable attachment handle and extend your arms straight back. With arms straight, slowly pull the cable to the thigh area, then return to the starting position.
IMPORTANT: The elbows can be slightly bent, but they must stay locked into position during the pullover. The goal is to try to minimize activity of the triceps.
Position upper back on ball. Grab cable handle attachment.
Keep arm straight, pull handle to thigh area.
Slowly return to start position. Repeat as needed.