Eccentric wrist extension with weight (Wrist extension strengthening eccentric, with dumbbell, over edge, palm down - assisted lift)

Start in a seated position with your forearm resting on a table and holding a weight in your hand with your palm facing downwards.
Using the other hand, lift your wrist up, keeping your forearm in contact with the table.
Remove your other hand and then slowly lower your raised hand back down without support.
Relax and repeat.