Resistance band plank ups are a good exercise to strengthen the core, shoulders, and arms. The plank ups are good for shoulder mobility and core endurance. Learn more about properly executing this exercise with the video above.
Regression
Make the move easier by moving closer to the anchor point to reduce tension or hold a plank while fighting the resistance.
Progression
Increase the intensity of this move by having your client move further away from their anchor, placing more tension on the Slastix.