Fly with dumbbells prone on a flat bench

Move the arms through a controlled arc with a slight bend in the elbows. Open or close only as far as you can without forcing the front of the shoulder. Prioritize control over speed. Maintain useful tension through the range and deliberately reset the starting position before the next repetition.

Do not turn the final repetitions into fast or partial movements. Aim to load shoulders and neck and upper trapezius without sacrificing position; at intermediate level, progress control first and then add load, repetitions or complexity. Make sure the bench is stable and that the shoulders, pelvis or feet do not shift during the set.