Instructions
Sitting on a bench or sturdy chair, hold two dumbbells using an overhand grip
Place your feet flat on the floor, at a distance that is about shoulder-width apart.
Leaning forward, rest the underside of your forearms on your upper thighs with your palms facing down. The front of your wrists should lie on top of your knees. This is the starting position.
Lower the dumbbells past your knees by bending only your wrists. Keep your forearms flat on your thighs.
Now curl the dumbbells upwards continuing past the starting position using only your wrists.