1. Stand upright holding a dumbbell in each hand, bent your elbows up to 90 degrees, guide the arms upwards until they are parallel to the ground, the arms and shoulders are in a line now.
2. Rotate the weights up as high as you can after that, let the forearms come back to the starting position and repeat several times.
Tips and Advises:
Make sure that your upper arms do not move and avoid swinging your upper body.