What Do Decline Dumbbell Flyes Do?

Decline dumbbell flys take your everyday weight bench from flat to an incline where your legs are higher than your chest and head. The advantage of this for the dumbbell fly is the exercise focuses on a different aspect of your chest muscles while also bringing in your upper back and triceps muscles. When you understand the muscles a decline dumbbell fly targets, you can perform the exercise for optimal effectiveness. Always talk with your physician before beginning a weightlifting program to ensure you do not have any medical conditions or injuries.

A decline dumbbell fly involves bringing dumbbells from an open-arm position to meet in the middle of your chest. Begin by lying on your back on a decline bench. Your feet should be firmly in place under the bench’s footrests for stability. Grasp a dumbbell in either hand and lift your arms just over your chest with your palms facing each other. Keep your elbows slightly bent as you open your arms, slowly lowering them toward the ground. Stop when your arms are even with your shoulders and your palms facing the ceiling. Contract your chest muscles to lift your arms back to your starting position, with your dumbbells almost touching. Repeat 10 to 12 times, rest for 30 seconds and repeat for one to two sets.

The chief goal of the decline dumbbell fly is to work your pectoralis major or chest muscle. This muscle is the larger of your two chest muscles -- the other is the pectoralis minor. Your pectoral muscles work closely with your deltoid or shoulder muscles to lift heavy objects. Sports Injury Clinic's example of when you use your pectoralis major is when you put on roll-on deodorant. Strong, defined pectoralis muscles can add definition and muscle tone to your chest.

Using the decline bench to perform the dumbbell fly exercise focuses more on the lower portion of the chest and front portion of your shoulders known as the anterior deltoid. An incline bench press targets the upper portion of the pectoralis major muscles, according to “Muscle & Fitness” magazine. The tendency in the decline fly can be to hold your arms too high, which can place unnecessary strain on your chest. By keeping your arms at a 45-degree angle from your torso, you can work the chest muscles while minimizing injury risk.

Additional muscles work with your chest muscles to perform the decline dumbbell fly exercise. This includes your biceps muscles on the front of your upper arm, which work alongside your chest muscles to lift the dumbbells. Other muscles act as stabilizers, working to help you maintain control of your dumbbells. This includes your wrist flexors, triceps and the brachialis muscles located near your biceps. By performing the decline dumbbell fly, you can strengthen both the chest muscles and the synergist and stabilizer muscles.