Your focus on the hollow hold is to drive your lower back into the ground. This challenges your entire core, and it also creates a body position that can easily be rocked in all directions (which is partly why hollow rocks are a good ab move in their own right). Maryniaks variations take advantage of that instability. Weights will try to pull you out of position from different directions. Your core's job: Fight to stay in position no matter what.
One of the most important pro tips on the hollow body is to keep you lower back pinned to the floor, Maryniak writes in a recent Instagram post. If you break that position during any hollow holds (and especially with loaded variations like these), you take the challenge out of your core and risk aggravating your low back.
For the first move, the dumbbell offset hollow hold, grab a light dumbbell in each hand, and extend one arm behind you and in line with your neck and the other straight out to your side. Both palms should face up toward the ceiling, and if you feel a strain in either elbow, allowing a slight bend can help.
Next up, the dumbbell hollow chest-fly negative. Use the same set of light dumbbells, hold them straight above your chest with a neutral grip to start. Maintaining a slight elbow bend, lower them toward the floor over the course of 4 seconds. Then, pull the weights into your chest and press them back up to start, really focusing on challenging your chest eccentrically, and just using the press as a reset.
In the last and most-challenging move, the two-point weighted hollow hold, place one light rubber weight plate (or some other counter load) on your legs, centered around your knees, and hold another with both hands behind you and in line with your neck.
For all of these moves, the number-one priority should always be on owning that pinned low-back position. Start with light weights, and if you are unable to keep your low back pressed firmly into the floor at all times, raising your arms and/or legs slightly closer to vertical will decrease the lever arms that your muscles have to fight.