barbell palms down wrist curl over a bench

Sit on a bench with your feet flat on the ground and your forearms resting on your thighs, palms facing down. Hold a barbell with an overhand grip, hands shoulder-width apart. Lower the barbell towards the ground by flexing your wrists, keeping your forearms stationary. Pause for a moment at the bottom, then slowly raise the barbell back up by extending your wrists. Repeat for the desired number of repetitions.