How to Use a Butterfly Weight Bench
The butterfly weight bench has arms that allow you to do the chest fly exercise, which is an isolation movement. Other chest exercises, such as the bench press, involve the triceps and shoulders as assisting muscles, but the butterfly exercise targets only the chest muscles. Because fewer muscles are involved, you should use less weight for the butterfly exercise than you do for a pressing exercise. On an upright butterfly bench, you sit while doing the exercise, but on a horizontal butterfly bench, you lie on your back to perform the movement.
Adjust the butterfly arms. Pull out the lock pin and set the butterfly arm so that when you sit on the bench and grab the handle, your upper arm is in line with your upper body, not behind or in front of it. Release the lock pin and ensure that it secures. Repeat this on the other side.
Select a weight that allows you to complete 12 to 15 repetitions. If you are using a selectorized butterfly bench, pull the weight pin out of the stack and slide it into the desired weight plate. If you are using a free-weight butterfly bench, slide weight plates on the weight tubes.
Sit or lie on the bench with your back firmly against the pad.
Extend your arms and grab the handles with your palms facing forward. Pull the handles slightly so that the weight lifts off the rack. This is the starting position.
Squeeze your shoulder blades together and lock your elbows into a slightly bent position. Maintain this body position throughout the set.
Exhale and pull your arms across your body until they almost touch. Do not allow your chest to cave inward during the movement. Keep your chest expanded. Pause for a count, inhale and slowly lower the weight back to the starting position.
If you can easily complete 20 repetitions with good form, increase the weight by 10 percent.
Not all butterfly benches have adjustable arms.
Focus on squeezing your chest as you pull your arms across your body.
Setting the butterfly arms too far back positions your upper arms behind your torso and places your shoulders in an extreme stretch position. You could injure your shoulders lifting a weight from this position.
Based in Austin, Texas, Jolie Johnson has been in the fitness industry for over 12 years and has been writing fitness-related articles since 2008 for various websites. She received her Bachelor of Arts in English and philosophy from the University of Illinois.