It's a bit like exercising the biceps brachii, except that the biceps brachii is exercised with the palm up and the wrist strength is exercised with the back of the hand up.

Wrist clock

Put your forearm on your leg or stool, hold the dumbbell with your palm down, bend your wrist down, then lift it, bend it again, and don't move your arm; Then palm up and grab the dumbbell.

Hand rotation and bending lifting

Sitting posture, the bell bearer's forearm is attached to the bench or sloping board, and his hand rotates inward and outward.

Bearing rope

Standing, a rope is tied to a round stick, and a dumbbell is tied to the other end of the rope. Hold the wooden stick with both hands, roll up the suspended heavy object forcibly, and then put it down slowly. Roll forward and then back. Repeat.

In addition, grasping the racket and the barbell is also an effective way to develop wrist strength.

There is also a kind of fitness equipment specially used to train wrist and arm strength. You can consider using it. It's available online.