Some of the most effective dumbbell exercises are bench press, alternating biceps curl and shoulder press. The bench press requires a bench in addition to dumbbells.
The bench press targets the chest, shoulders and triceps. The workout can be modified to target lower and upper pectoral muscles if the weight bench has incline/decline capability. The alternating biceps curl strengthens biceps and, to a lesser degree, forearm muscles. It can also be performed by raising both dumbbells at the same time as opposed to alternating arms. The shoulder press targets the deltoid muscles and is performed by either alternating both arms or lifting them simultaneously.