Sometimes called butterfly arms, the butterfly machine is a strength training station for targeting your chest muscles.
The butterfly exercise can be also done with dumbbells or cable.
Using the butterfly machine, isolates your pecs the most. The chest is the one doing most of the movement here, with a little assistance from the shoulders, biceps and triceps.
How to do
Sit on the upright bench with your feet flat on the floor. Place your forearms against the arm pads. Your forearms should be perpendicular to the floor and your upper arms parallel to the floor. Push against the arms enough to lift the weights off the stack.
Squeeze against the weight until the butterfly arms almost touch in front of your chest. Keep your chest elevated; don't let it sink in.
Pause for a count then slowly lower back to the starting position.
The chest fly machine might put way too much stress on your shoulder joint. Leading to injuries ranging from minor muscle tears to full shoulder dislocation.
It also might overstretch the front of your delts, while tightening the rear delts. If you sit in front of a desk all day, you might already have your shoulders rounded to the front, and the fly might just make this condition worse.
Be careful if you had any previous shoulder problems.