The plank pull-through is a variation of the plank that adds anti-rotational elements of trunk and hip stability.
From a plank position, lift one arm and pull a dumbbell or similar from the opposite side under your body. Replace that arm on the floor and use the other arm to pull the weight back to the original side.
The plank pull-through adds difficulty by creating instability and forcing the trunk and hips to resist rotation and changing forces.
The plank pull-through can be done at the end of training sessions for 3-5 sets of 10-30 reps.
The plank pull-through can be done using a band rather than a dumbbell or other weight.