Using the trap bar for squats has been a go to workout for me this off season. This movement perfectly simulates the kind of squat position you get into during a block in beach volleyball.
If you have never done these before start light and focus on form. Act like you’re sitting back on a chair and hinge at the hips. For maximum benefit try to explode up as you stand. It sounds silly but I imagine going up for a block every single rep and it really makes a difference in my intensity!!