Step-by-Step Instructions

1. 1

   Lie on a flat bench holding a dumbbell in each hand above your chest with arms extended and a slight bend in the elbows (roughly 15-20 degrees).

2. 2

   Retract your shoulder blades and press them into the bench to stabilize the shoulder joint and protect the anterior capsule.

3. 3

   Slowly lower the dumbbells outward in a wide arc, maintaining the fixed elbow angle, until you feel a deep stretch across the chest and your upper arms are roughly in line with the bench.

4. 4

   Reverse the motion by squeezing the pecs to bring the dumbbells back together over mid-chest in the same sweeping arc.

5. 5

   At the top, focus on contracting the inner chest fibers without clanking the dumbbells together.

6. 6

   Use a controlled 3-second eccentric and a 1-2 second concentric tempo to maximize time under tension.

Common Mistakes

• Bending the elbows progressively deeper during the rep, converting the fly into a pressing motion and reducing pec isolation.

• Lowering the dumbbells too far below the bench plane, which overstretches the anterior shoulder capsule and risks labral strain.

• Using too heavy a load that forces jerky, momentum-driven reps instead of smooth, controlled arcs.

• Failing to retract the scapulae, which rolls the shoulders forward and shifts stress to the anterior deltoids.

About This Exercise

The dumbbell chest fly is a single-joint isolation exercise that targets the sternal and clavicular fibers of the pectoralis major by moving the arms through horizontal adduction on a flat bench. The deep eccentric stretch under load makes this exercise particularly effective for stimulating pec hypertrophy through mechanical tension and muscle damage pathways. Best programmed as an accessory movement after compound pressing to accumulate additional chest volume without fatiguing the triceps.