The mid-line Hold builds strength in the core abdominal muscles. It is important to keep the legs quiet while holding the cable at your midpoint. Small twists from right to left keeping the abdominals tight and the hips stationary and head up in good posture will ensure maximum benefit.
The next variation on this is a Hold and Twist to the right or left. In this version allow the hips to twist as they would in a golf or baseball swing. This version also builds stability in the hips and legs.