Dumbell Flyes (Chest Fly, Pectoral Fly) Guide

The chest fly or pectoral fly (abbreviated to pec fly) primarily works the pectoralis major muscles to move the arms horizontally forward. If medially (internally) rotated, it is assisted in this by the anterior (front) head of the deltoideus in transverse flexion. If laterally (externally) rotated, the contribution of the deltoid is lessened and the pec major is strongly emphasized as the transverse adductor.

The movement is performed lying on the back on a bench, starting weights extended above the chest, meeting at the midsagittal plane. The arms are lowered through an arc passing through the transverse plane, terminating when the arm is roughly parallel to the floor, then returning to the starting position and repeating.