SETUP: Mount a decline bench, and hold a plate with arms extended above your chest.
REP: Sit up by squeezing your abs hard. As you rise, move your arms overhead. The top position will engage the lower traps. Return to the start point in a controlled manner.
TIP: You can make this slightly easier by starting the rep with the wieght at chest level (arms not extended) and pressing the weight as you perform the rep.