Hold it like a tray and the bicep peak has nowhere to hide.
Keep it flat like a tray of water, tilt it forward and the tension spills off.
Cupping one end of a dumbbell like a tray forces your biceps to do more than just bend the elbow. Keeping the plate level means holding maximum supination through the entire rep, which keeps the biceps fully switched on and squeezes hard at the top where curls usually go slack. It earns a slot as a finisher or a fix for lifters who rush through regular curls without ever feeling their biceps work.
The tray position forces your palms to stay turned up and level, which keeps the biceps under full tension at the top of the curl. It removes the wrist flick and momentum that let you cheat normal curls.
Lighter than your usual curl weight. The whole value is in the level plate and the top squeeze, and a heavy bell you cannot keep flat just turns it into a sloppy front raise.
Your wrists are breaking back as you fatigue, which lets the tension spill off the biceps. Keep the elbows pinned to your sides and imagine the plate is a tray of drinks you cannot spill.
