Decline Dumbbell Fly

The decline dumbbell fly targets the lower fibres of the pectoralis major, the portion that a flat bench trains less directly and that gives the chest its lower border. Lying head-down changes the angle between the arm and the torso, so the line along which the pectorals shorten runs downward and inward rather than straight across. Adding a rotation of the wrists as the dumbbells come together increases the contraction at the top, since the pectoral both adducts and internally rotates the arm. Keep a slight fixed bend in the elbows for the whole set: straightening them puts the strain on the joint, and bending them further turns the fly into a press. Lower only until you feel a stretch across the chest, not until the shoulders roll forward, which is the point where the joint takes over from the muscle.