Dumbbell Fly

So-called fly exercises are popular exercises for isolating the chest muscles as much as possible. The primary function during this exercise is pulling the upper arms forward through the pectoralis major. Because the arms maintain the same curvature throughout the movement, the triceps are required much less than during the bench press. The biceps must nevertheless be kept under continuous tension to hold the arms in a slightly bent position.

Flyes can be performed with dumbbells, but also with machines or cables.

Because the pectoralis major is compressed in the middle of the chest at the end of the movement, it is sometimes thought that this exercise trains the “inner” chest. This idea is especially associated with cable variations that provide tension all the way to the final position. Regarding the fiber direction of the pectoralis major, however, there is no “inner” chest (nor an “outer” chest). The portion of the fibers near the sternum also does not appear to be capable of being activated separately by particular exercises. You train this muscle along the entire length of its fibers. At most, different angles (hands ending at navel height versus shoulder height, for example) can place more emphasis on the lower or upper fibers of the chest.

Dumbbell Fly execution

1
Move your arms out to the sides as if you want to embrace someone. Depending on your shoulder mobility, your hands end slightly in front of or beside your torso. Because of the bend in your arms, your elbows are slightly closer to the floor.
2
Bring your hands back together as if embracing a (large) person.

Dumbbell Fly

Active muscles:

Pectoralis major (large chest muscle)
Anterior deltoid (front fibers of the shoulder muscle)
Serratus anterior
Coracobrachialis

Stabilizing muscles:

Rotator cuff (stabilizing shoulder muscles, supraspinatus, subscapularis, teres major, teres minor)
Biceps brachii
Serratus
Trapezius
Triceps brachii
Latissimus dorsi
Core muscles

Dumbbell Fly preparation

Choose dumbbells of the appropriate weight for the desired number of repetitions.
Sit on the end of the bench with the dumbbells upright on your knees.
Lie back and, in the same movement, bring the dumbbells one at a time toward your chest with your knees. Place your feet back on the floor.
Keep your hands in a pronated position (thumbs facing your face). Keep your elbows close to your sides.
Press both arms straight upward, but maintain a slight bend in your arms. This is your starting position.

Dumbbell Fly technique

One of the most common mistakes in this exercise is bending and straightening the arms. Do not straighten your arms when bringing your hands back; keep them under tension. This prevents you from having to bend them again on the way forward and therefore prevents excessive involvement of the biceps and its (distal) attachment.

Another common mistake is intending to perform a dumbbell fly but turning it into a dumbbell chest press. The hands then begin with the palms facing the feet instead of facing each other. The movement itself is subsequently more of a forward push, as in the bench press, rather than an embracing movement.

Keep your elbows below shoulder level in the starting and ending positions. This is to prevent excessive involvement and a shoulder position that is susceptible to injury.

Do not bring your elbows too far back at the beginning and end of the movement. They should not come far beyond the torso. A safe starting point is to bring them to the torso. Depending on your shoulder mobility, you can go slightly farther back for a greater range of motion.