Single Arm Dumbbell Fly

The single arm dumbbell fly is a chest isolation exercise performed one side at a time on a flat bench, and working unilaterally offers two advantages over the two-dumbbell version. The first is range: with no second dumbbell in the way, the arm can travel a little lower and the pectoral reaches a fuller stretched position, which is where this exercise delivers its stimulus. The second is that each side carries exactly its own load, so strength differences stop hiding behind the stronger arm. Keep a slight, constant bend in the elbow throughout the movement: straightening it completely shifts the strain onto the shoulder joint, and bending it further turns the fly into a press. The weight should be modest, because the stretched position is demanding for the joint even when it feels manageable.