Unilateral, or one-arm, chest exercises can effectively isolate one side of your chest. Although cable and chest-strengthening machines might give you the option of working one arm at a time, dumbbells can also be used unilaterally. By working one arm at a time, you can really focus on the muscle you're working, while at the same time stimulating more muscle tissue, correcting strength imbalances and engaging your core to stabilize your body. For optimal results, perform exercises like bench presses and dumbbell flyes with perfect form.
Unilateral Bench Press
Lie face up on a bench with your knees bent and your feet flat on the floor.
Hold a dumbbell in your right hand and extend your right arm directly above the right side of your chest. Raise your other hand and grasp the edge of the bench at the left side of your head.
Engage your core to help balance your body and squeeze your shoulder blades together. Your shoulder blades should be touching the bench throughout the exercise.
Bend your right elbow out and lower the dumbbell toward your chest until your right upper arm is parallel to the floor. Avoid dropping the weight by really controlling the motion.
Pause for two seconds and then straighten your arm, using your chest, core and triceps to push the weight back to the starting point. Perform eight to 12 repetitions before switching arms to finish the first set. Work your way up to completing two to three sets.
Unilateral Chest Fly
Lie face up on a bench, bend your knees and place your feet flat on the floor.
Hold a dumbbell in your right hand and grasp the edge of the bench at the left side of your face with your other hand.
Engage your core and then extend your right arm above your chest, keeping your elbow slightly bent.
Lower the weight out to your right side until your upper arm is parallel to the floor. You should feel a stretch in the right side of your chest going into your right upper arm.
Pause for two seconds and then raise your arm back to the starting point, really squeezing the right side of your chest during the motion. Repeat this eight to 12 times and then switch arms to finish the first set. Work your way up to finishing two to three sets.