The decline dumbbell press primarily works your chest muscles, followed by your shoulders and triceps. Decline dumbbell presses help build definition in the lower portion of your pectoral, or chest, muscles. Using dumbbells also speeds up visible results, and you gain a greater range of motion using dumbbells compared to a barbell. Learn proper technique with a personal trainer or fitness instructor. It’s important to check with your health care provider before beginning any new exercise program.