I like to include some single arm dumbbell training in my rehab and performance training with my clients. This allows for observation of any frank weakness and provides an opportunity to work on eliminating asymmetries and imbalances. This particular variation of the dumbbell fly also provides unique anti-rotational challenges for the torso.
Choose a light weight initially to ensure safety and proper form. Position the body in a supine bridge on a stability ball. Extend both arms so that they are perpendicular to the body. Slowly lower the weighted arm until the upper arm is roughly parallel to the floor (no deeper) while allowing the elbow to bend and remain bent throughout the descent. Briefly pause at the bottom and then return to the start position.

Perform 5-10 repetitions on each side. The goal is to minimize any rotational movement focusing on keeping the shoulders level while maintaining a good table top position. Once the client is no longer able to control the full descent without visible compensation, stop the exercise or reduce the range of motion/load to a point where he/she can once again execute the movement correctly.

This exercise is an excellent exercise to improve core stability, anti-rotation strength and improve shoulder strength and stability. It can be used for overhead athletes (e.g. swimmers, tennis players, baseball/softball players, etc.) as well as the general population who may exhibit upper body/core asymmetry or dysfunction during movement or strength assessments.

I encourage spotting the clients in a half kneeling position with the hand (s) just below the loaded upper arm to ensure the elbow does not drop below parallel or in the event of sudden fatigue/loss of control to protect the anterior shoulder. 

1. Perform the movement on a flat bench

2. If the bench version is still too difficult, perform the exercise on the floor as this allows for tactile feedback and prevents the elbow from dropping below the shoulder

For clients with a history of anterior shoulder instability or subluxations, I suggest mastering the bilateral version on a bench and then the stability ball prior to progressing to the unilateral version. Once they are ready for the unilateral version, follow the regression methods listed above prior to moving to the full exercise on the stability ball.

Brian Schiff, PT, OCS, CSCS, is a licensed physical therapist, respected author and fitness professional. Currently, he serves as the supervisor for EXOS API at Raleigh Orthopaedic. Brian conducts live continuing education webinars and presents nationally at professional conferences and seminars on injury prevention, rehab and sport-specific training. For more information on his products and services, visit