Dumbbell Flyes

Lie on a flat bench with a dumbbell in each hand, arms extended above your chest with palms facing each other and a slight bend in your elbows. Lower the dumbbells in a wide arc until you feel a deep stretch across your chest, then reverse the arc to bring the weights back together above your chest.

Pro Tips

• Maintain a slight bend in your elbows — never fully straighten or collapse them
• Think of hugging a large tree; the motion is an arc, not a press
• Use lighter weight than you think; this is an isolation exercise, not a strength move

Muscles worked

Primary: Pectoralis major — loaded through shoulder horizontal adduction (the arc of bringing the arms together over the chest). Unlike pressing movements that also involve significant tricep contribution, the fly’s straight-arm position minimises elbow extension, making the pec do most of the work through its full horizontal adduction range.

Supporting: Anterior deltoid (assists at the top of the arc when the arms are above the shoulder plane), coracobrachialis, serratus anterior (scapular protraction at peak contraction when hands meet).

Common mistakes

Straightening the arms: Keeping the elbows fully locked under load transfers the full stretch force from the pec to the shoulder capsule — a structure that is not designed to be the primary load path. Maintain a fixed soft elbow bend (15–20 degrees) throughout the entire arc.

Using too much weight: The fly is a stretch-loaded isolation movement. Heavy dumbbells shorten the usable range of motion as the stretch force at the bottom exceeds what the shoulder can comfortably support, forcing a pressing pattern rather than a fly pattern. Effective flyes use lighter weights through a full arc.

Tension dropping at the top: Allowing the dumbbells to come into contact at the top removes the pec from load at its most contracted position. Stop just short of contact — keep the pec under tension throughout.

Flat back on a flat bench: Maintaining a slight arch in the lower back and retracting the shoulder blades keeps the chest in a stable, elevated position that improves pec activation. Flattening the back into the bench flattens the chest and reduces the effective arc of the fly.

Programming notes

Dumbbell flyes are used as an isolation finisher after compound pressing movements — rarely as a primary or secondary chest exercise. Their value is in loading the pec through horizontal adduction, the chest’s primary function that bench pressing (with its elbow-extension component) only partially trains.

Typical programming: 3–4 sets of 12–15 repetitions, placed at the end of a push or chest session. The cable fly is a mechanically superior alternative for most lifters (constant tension vs. tension that drops at the bottom for dumbbells), but dumbbell flyes remain valuable where cables are unavailable.

Frequently asked questions

Are dumbbell flyes better than cable flyes for chest development?

Cable flyes provide constant tension throughout the entire arc, including at the bottom where the pec is most stretched, making them mechanically superior for hypertrophy in most circumstances. Dumbbell flyes lose tension at the bottom of the arc because gravity pulls straight down rather than across the chest. That said, dumbbell flyes are highly effective and remain a proven chest builder — if you only have access to dumbbells, you are not missing out significantly. Use cables when available; use dumbbells when cables are not.

How heavy should you go on dumbbell flyes?

Lighter than you expect. The dumbbell fly is a stretch-loaded isolation movement, not a strength exercise, and the stretch force at the bottom of the arc increases dramatically with load. If you cannot lower the dumbbells to chest level with a controlled arc and a consistent elbow bend, the weight is too heavy. Most lifters who can flat bench press 40 kg dumbbells for reps will use 14–18 kg dumbbells for flyes. Start conservatively and prioritise the full arc over the number on the dumbbell.

Should you do dumbbell flyes before or after bench press?

After. Compound pressing movements — flat bench, incline bench, dips — require full tricep and shoulder involvement alongside the chest, and you want those muscles fresh for the heavy work. Flyes pre-fatigue the pec without contributing to pressing strength, which means you will underperform on your primary lift. Sequence flyes at the end of your session as an isolation finisher, once the compound work is complete.