One-Arm Dumbbell Wrist Curl Over a Bench
Grab a dumbbell with your right hand, with a supinated grip (palms up). Kneel down on both of your knees (or crunch) so that your body is facing the flat bench. Bring the dumbbell up so that your right forearm is resting against the flat bench. Your wrist should be hanging over the edge.
Start out by curling your wrist upwards.
Slowly lower your wrist back down to the starting position. Repeat the exercise according to the training plan then switch arms.