Star Side Plank
The star side plank is a simple exercise for lateral stability of both the trunk and hips.
Lie on the floor on your side with the lower arm bent and forearm on the floor. Lift the hips into a side plank position, then lift the top leg up and hold this position for the prescribed duration.
The star side plank strengthens the obliques and QL for lateral trunk stability, and adds strength work to the lateral hip for improved hip stability.
3-4 sets of max holds (not to actual failure) at the end of training sessions is a good prescription. Shorter, less demanding durations can be used in a warm-up for preparation as well.
The star side plank can be done on the elbow or a straight arm, and the leg can be help up in place or lifted for repeated reps, or it can be performed as a side plank lift plus leg lift for repetitions.