Place the dumbbell on its end at the end of a flat bench. Lie face up across the bench, with your upper back and shoulders on the bench.
Grasp the dumbbell with both hands, with your palms up and pressing the top plates of the dumbbell, and with your thumbs curling around the handle. Extend your arms and raise the dumbbell over your chest.
Slowly lower the dumbbell behind your head, slightly bending your elbows.
Slowly return the dumbbell to the position over your chest.
