Position yourself with one hand and knee braced on a bench for stability, holding a dumbbell in the opposite hand. With a slight bend in your elbow, lift the dumbbell outward and slightly upward in a controlled arc until your arm is roughly parallel to the floor. Focus on squeezing the rear shoulder and upper back muscles at the top of the movement, then slowly lower the weight back to the starting position while keeping your torso still and avoiding momentum.
Log your dumbbell one arm reverse fly with support version 2 sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.