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Chest Fly

Draftstrength50%intermediate⬤ limited evidence

View FHIR resourceFHIR R4 ActivityDefinition — the interoperable form of this exercise

Positions & Range of Motion

Start: Supine on a flat bench, dumbbells held above the chest with palms facing each other and a soft fixed bend in the elbows
End: Arms lowered in a wide arc to about bench level until a gentle stretch is felt across the chest, then squeezed back together over the mid-chest along the same arc
Range of Motion: Shoulder horizontal abduction to a chest-level stretch and back to horizontal adduction over the chest, elbow angle held constant throughout

How to Perform

Lie supine on a flat bench holding dumbbells above the chest with palms facing each other and a soft bend in the elbows. Lower the arms out to the sides in a wide arc until a gentle stretch is felt across the chest, then squeeze the arms back together over the chest along the same arc, keeping the elbow angle constant throughout.

Watch on YouTube↗

Opens a YouTube search for “Chest Fly”

Equipment:dumbbellsflat bench

Starting position: supine

Coaching Cues

1
Imagine hugging a large barrel — keep that same gentle elbow bend the whole rep.
(external)
2
Lower until you feel a comfortable stretch across the chest, not pinching in the front of the shoulder.
(internal)
3
Keep your shoulder blades pinched together and pressed into the bench from start to finish.
(internal)
4
Bring the dumbbells together over the middle of your chest, not over your face or belly.
(external)

Evidence-Based Dosing & EMG Data

Recommended Dosing

2-4 sets of 8-15 repetitions, 2x per week per general resistance-training guidelines for hypertrophy and strength; select a load leaving 1-3 reps in reserve. No fly-specific dosing trials exist.

EMG Activation Data

Surface EMG comparisons of horizontal press and fly variations generally show high pectoralis major activation during the dumbbell fly, in a range comparable to the bench press at matched relative intensities, with substantially less triceps brachii involvement because the elbow angle is held constant. Anterior deltoid activity is moderate to high. The bottom (stretched) position places the pectoralis major under load at long muscle length, which biases mechanical tension there; it is also the position of greatest anterior shoulder stress, which motivates the limited-range floor variation for irritable shoulders. These are general findings from small EMG studies; the fly is far less studied than the bench press.

Muscles Involved (10)

Primary Movers

Pectoralis Major— Prime mover for shoulder horizontal adduction; loaded through a long arc including a stretched position at the bottom of the movement.

Secondary Movers

Anterior Deltoid— Assists horizontal adduction/flexion, especially through the top half of the arc.

Stabilizers

Biceps Brachii— Works isometrically to hold the fixed soft-elbow flexion angle against the load; not a meaningful contributor to horizontal adduction itself.

Serratus Anterior— Stabilizes the scapula against the thorax as the arms move through the arc.

Subscapularis— Anterior rotator cuff — resists anterior humeral head translation and maintains glenohumeral centration, particularly in the stretched bottom position.

Infraspinatus— Posterior rotator cuff — contributes to glenohumeral centration and stability during the loaded stretch.

Teres Minor— Posterior rotator cuff — assists glenohumeral stabilization/centration through the arc.

Middle Trapezius— Scapular retractor working isometrically to hold the set scapular position on the bench; not a stretched antagonist of the movement.

Rhomboid Major— Scapular retractor stabilizing the retracted scapula against protraction, forming a force couple with serratus anterior.

Lengthened / Stretched

Posterior Deltoid— Direct antagonist (horizontal abductor) of shoulder horizontal adduction; lengthens under control through the concentric phase.

Easier Variations ↓

Floor Chest Fly

Perform the fly lying on the floor; the floor stops the arms at roughly neutral, limiting end-range shoulder stretch and reducing strain for beginners or those with anterior shoulder irritability.

Band Chest Fly (Standing)

Anchor a resistance band behind you and bring the arms together in a hugging arc; lighter, easily scalable resistance with a friendlier strength curve at end range.

Harder Variations ↑

Cable Fly

Perform the fly on a cable crossover; cables keep tension on the pectoralis major through the entire arc, including the fully adducted position where dumbbell torque drops off.

Slow-Eccentric Dumbbell Fly

Use a 3-4 second lowering phase into the stretched position to increase mechanical tension at long muscle length, a stimulus associated with hypertrophy in stretch-emphasized training.

Target Movements (1)

Shoulder Horizontal AdductionGlenohumeral Joint

Why This Exercise Matters

Everyday activities this exercise helps you do — essential means it directly trains the capacity the task needs:

Pushing (Doors, Carts)Throwing & Overhead Sport

Research Notes

claude-researched 2026-07; muscle/movement links validated against the roster. Adversarial clinical verification pending — do not promote past needs_review without human review.