Stand with a dumbbell in each hand, palms facing backward. Your feet should be about shoulder width apart. Maintain a slight bend in your elbows throughout the exercise so that your arms are straight, but not quite locked. Lift the weight in your left hand in front of you in a wide arc until it is slightly higher than shoulder height. With a smooth, controlled motion, lower the weight while simutaneously lifting the weight in your right hand, so that both arms are in motion at the same time. Do not cheat by swinging or leaning backwards! Can also be done with two dumbbells at the same time or a barbell.