Decline Dumbbell Fly: Muscles Worked, How To Do & Tips

The decline dumbbell fly is a variation of the traditional dumbbell fly, performed on a decline bench set at an angle of 30 to 45 degrees. This positioning puts more focus on the lower portion of your chest muscles (lower pec).

Because it can lessen anterior deltoid involvement and impingement risk if form is perfect, the decline angle may be more shoulder-friendly for certain people than flat or incline flyes.

Unlike compound pressing movements that involve multiple joints and muscle groups, the dumbbell fly isolates the pectoral muscles, allowing for a focused stretch and contraction.

Muscles Worked

• Primary Muscles: Pectoralis Major (sternal/lower fibers)
• Secondary Assistors: Anterior Deltoid, Coracobrachialis
• Stabilising Muscles: Serratus Anterior, Rotator Cuff Group (supraspinatus, infraspinatus, teres minor, subscapularis), Biceps Brachii (long head – isometric elbow support), Rhomboids & Middle Trapezius (scapular retraction) and Rectus Abdominis & Obliques.

How To Do

1. Adjust your decline bench to an angle between 15 to 30 degrees.
2. Secure your feet firmly in the leg braces or footpads. You should feel locked in and stable before even thinking about picking up the weights.
3. Grip the dumbbells firmly with a neutral grip (palms facing each other). Place one dumbbell on each thigh so that they are resting vertically next to your knees.
4. Take a deep breath, brace your core, and then lie back onto the bench simultaneously.
5. Once fully reclined, your arms should be extended directly above your lower chest, almost perpendicular to the floor (not your body).
6. Maintain a slight bend in your elbows. If your arms straighten too much, you risk elbow strain; if they bend too much, it becomes a press.
7. Slowly lower your arms out to the sides in a wide arc until you feel a stretch in your chest. Inhale as you perform this part of the movement. 
8. Do not overstretch. Pushing beyond your comfortable range of motion, especially with weight, can put excessive stress on the shoulder joint (anterior capsule).
9. From the stretched position, powerfully reverse the motion by squeezing your pectoral muscles. Think about bringing your biceps towards each other, or as if you’re trying to crush something between your inner arms.
10. Bring the dumbbells back up until they are almost touching (or lightly touch, but don’t clang them) directly above your lower chest. Focus on a hard squeeze in your pecs at the top of the movement.

Tips and Form

• Ensure that your shoulder blades are retracted (pulled back and down) to protect your shoulders and improve chest activation.
• Your elbows should have a slight, fixed bend throughout the entire exercise – think “soft elbows,” never locked out or excessively bent. The movement is a wide arc originating solely from the shoulder joint.
• Lower the dumbbells only until you feel a good, comfortable stretch across your lower chest. For most, this is when your hands are at about chest level, or your upper arms are parallel to the floor. Avoid going too deep in the stretch phase, as this can strain your shoulder joints and rotator cuff unnecessarily.
• The dumbbells must travel in a smooth, wide, arcing motion out to your sides on the way down, and back up in the same arc.
• Bring the dumbbells close together or to a very light touch at the top of the movement, but avoid letting them crash or clang together.
• Slow down both the lowering (eccentric) and lifting (concentric) phases to increase time under tension. (Feel the muscle contraction). I always feel the same during my workout.

Variations and Alternatives

• Cable Decline Fly: Offers constant tension throughout the movement.
• Machine Decline Fly: Great for beginners learning the movement pattern.
• Single-Arm Decline Fly: This exercise helps address muscle imbalances.

FAQ

How many sets and reps should I do?

For muscle growth (hypertrophy), perform 3–4 sets of 8–12 reps. Do 4–5 sets of 15-20+ reps with lighter weights for endurance. Beginners should start with 2–3 sets of 10–12 reps using lighter weights.

Can beginners do decline dumbbell flyes?

Yes, but it’s recommended that you master the flat bench fly first and start with lightweights. Use machines or cables initially to familiarise yourself with the movement pattern.

How often should I include this exercise in my routine?

Include decline dumbbell flyes 1–2 times per week as part of your chest workout, allowing at least 48 hours between sessions for proper recovery.