The shoulder is an extremely dynamic joint with an incredible range of motion and the power to throw, punch, push and more. But just putting on mass isn’t the answer: For strong and healthy shoulders, you must regularly perform some maintenance exercises to ensure equal development, coordination of the smaller stabilizing muscles and prevent injury. Here are two exercises that’ll help make sure your deltoids are the picture of health.Side-Lying Dumbbell External RotationThis targets the rotator cuff and rear deltoid. You’ll want to use dumbbells that are no heavier than 5 pounds. We’re serious; heavier is not better here.Lie on one side on the floor or a bench.Grasp a dumbbell in your free hand.Keep your elbow bent 90 degrees and rest it on your hip to keep your upper arm pinned against your body and your forearm in front of your midsection.Rotate your upper arm away from the center of your body.Squeeze your shoulder blades together and reverse the movement, keeping your elbow bent.Do 20-30 reps without resting, then complete 1-2 more sets before switching sides.Take two seconds to raise the weight, but lower it in six seconds; don’t use jerky movements.Quality reps are more important than the amount of weight you use.The Empty-Can Field GoalIt may have an odd name, but this exercise effectively targets the rotator cuff, rear delts and lower traps. Again, you’ll want to use dumbbells no heavier than 5 pounds.Stand erect holding dumbbells the “cans” by your sides.Keeping your elbows slightly bent, turn your wrists so your thumbs point toward the floor empty the cans, then slowly raise both arms straight out to your sides.As your arms reach shoulder level, turn your wrists to point your thumbs toward your body. Continue raising your arms until your elbows come to ear level.Rotate your shoulders so your thumbs point backward and squeeze your shoulder blades together, then slowly return to the start.Avoid arching your back and sticking out your chin as you raise the weights.Keep the weight light and the tempo controlled.