Exercise Advice: This exercise is very similar to both the regular dumbbell flyes and cable flat bench flyes. The only difference is that you will be using only one arm at a time to perform this exercise. Position yourself on a free-standing flat bench, flat on your back. Have your spotter hand you a dumbbell. When you begin this movement, you want your arm to be stretched out wide to your side with your elbow slightly bent and your palm facing inward, toward the bench. When you lift the dumbbell up, visualize hugging a giant tree trunk with that arm. When returning to the start position, be sure to lower the dumbbell in a slow and controlled fashion. Repeat this movement for as many repetitions as you can until failure. Remember to always use a spotter when performing this and almost every other free weight exercise!