HOW: Get set-up sitting upright holding a dumbbell with the side you want to exercise. You can support your arm on a surface if you'd like, but have your hand and wrist unsupported off the edge of the surface. Position your elbow bent in 90 degrees of flexion with your palm facing up. While maintaining arm and elbow position, perform concentric and eccentric wrist flexion and repeat. You can also use your other hand for resistance if you'd like. See video for more tips and instructions.
FEEL: You should feel the muscles on the inside of your forearm working as well as other muscles in your forearm and hand to help with gripping the dumbbell. You may feel tension on the inside of your elbow as well.