About 40% of 1rep max only because of the way we do them. Are isometric is not just holding the weight it is pushing against the bar as hard as posible, your partners make sure the bar doesn't move, then they let go of the bar and let you rep out six clean reps repeat then 3 reps then hold then one rep, right out of Jay Shroeder's playbood, works well for athletes IMO who need speed and explosive power