Isometric-Dynamic Contrast on Pendulum Bodybuilding?

When holding the weight at mid-point, should i hold the weight during the concentric movement or eccentric movement? For example :Isometric-dynamic contrast standing barbell curl. Do i need to hold when lifting the weight up or move the weight down?

Both work and I use both Holding during the concentric is harder so you will use less weight. Really good to fix a technical mistake or a weak point in a lift. Doing the hold during the eccentric allows you to use more weight and if better for overall growth.