Edward R. Laskowski, M.D.: The reverse fly is an exercise you can do with dumbbells to target the muscles in the upper back. During a reverse fly, you work the rhomboid muscles in your upper back and shoulder region. Strong upper back muscles help balance your shoulder strength and help protect your shoulder from injury.
Nicole L. Campbell: To do a reverse fly with dumbbells, sit with your knees bent and hold a dumbbell in each hand. Lean forward, letting your arms hang down next to your calves with your elbows slightly bent. Slowly raise the weights until your elbows are level with your shoulders. Then slowly lower the weights to the starting position. You'll feel tension in your shoulders and the muscles across your upper back.
When you're doing the reverse fly, be careful not to arch or hunch your back. Also be careful not to swing the weights. Instead use your upper back muscles to control the motion.
For most people, one set of 12 to 15 repetitions is adequate.
If you have back problems or you're unable to do this exercise with good form, you can do the same motion while lying on your stomach on a bench.
Remember, for best results, do not arch or hunch your back during the exercise. Keep your movements smooth and controlled.