Performing the: A Step-by-Step Tutorial Landmine Floor One Arm Chest Fly
Lie down on your back perpendicular to the barbell with your feet flat on the floor and your knees bent.
Grab the end of the barbell with one hand, extend your arm fully, and hold it directly above your chest, this is your starting position.
Slowly lower the barbell in a wide arc until it's level with your chest, keeping your arm slightly bent.
Reverse the movement and bring the barbell back to the starting position, squeezing your chest muscles at the top of the movement. Repeat for the desired number of repetitions before switching to the other arm.