How To Do Pec Deck Flyes For Real Results – Form, Tips, and Mistakes

Man performing pec deck flyes

Pec Deck Flyes also known as butterflies are a great isolation exercise for your Pectoralis Major. The pec deck fly is safer than dumbbell flyes and you are less able to cheat. You can still get injured if you don’t follow these tips.

Pec Deck Fly Summary

  • Primary Muscles Worked: Pectoralis Major, Sternal
  • Other Muscles (Secondary) Worked: Pectoralis Major Clavicular, Pectoralis Minor, Serratus Anterior
  • Equipment: Pec Deck Lever Machine
  • Mechanics Type: Isolation
  • Force: Push
  • Utility: Auxiliary

How To Use The Pec Deck Fly Machine Properly

Like most exercises, the setup is very important. The pec deck fly machine is adjustable. Although not every pec deck machine can the arms be adjusted, all will likely have a seat adjustment. Adjusting the height of the seat is important for your shoulders and to prevent injuries. You want your elbows to be slightly lower than your shoulders and in line with your chest. Because if your elbows are too high you are putting unnecessary tension on your shoulders.

Pec Deck Step-by-Step

  • First, adjust the seat so start your elbows are slightly below your shoulders and in line with your chest.
  • If your peck deck fly machine has a leg pedal that moves the arms forward, use that to move the arms so your arms are in line with your torso.
  • Before you begin your first rep breathe in so that you can breath out on the contraction and in on the expansion.
  • While pressing your back against the seat pull the arms of the machine together using your chest.
  • Then squeeze your chest and hold for a second.
  • Next, slowly return the arms to the starting position.
  • Finally, repeat for your desired number of reps.
Man performing flies pec deck flyes machine

Utilized Muscles

Target (Agonist) Muscles

  • Pectoralis Major, Sternal

Synergist Muscles

  • Pectoralis Major, Clavicular
  • Pectoralis Minor
  • Serratus Anterior

Stabilizers Muscles

  • None

The Pec Deck vs. Fly Machine By Dr. Jim Stoppani

Pec Deck vs. Machine Fly by Jim Stoppani

Tips for Better Results With Pec Deck Fly and Proper From

Even though the pec deck fly machine seems pretty simple, there are a few ways to maximize your results of this exercise.

  • Always Perform Proper Setup. Preventing injuries during exercise is very important and the setup is key to preventing shoulder injuries during peck deck flyes. As discuss earlier you want your elbows slightly lower than your shoulders. If you are suffering from a shoulder injury already you should read Building Muscle Despite Shoulder Joint Pain From Lifting Weights.
  • Keep Your Chest Engaged. To maximize this exercise or any resistance training you want to maintain your target muscle under tension. In order to maintain your chest under tension, you can not let the weights rest between reps. Specifically, this is why some machines have a leg pedal to lift the weights up slightly at the beginning of the exercise.

Frequent Mistakes You Want to Be Sure To Avoid On Pec Deck Flyes

Performing the pec deck flyes improperly can lead to shoulder injuries, or you may just not see any results. Fortunately, the pec deck machine is one that it is very difficult to cheat on.

  • Resting in the Open Position. As soon as the weight plates touch your chest is no longer under tension. The open arm position is usually the most challenging part of the lift and where most of the muscle growth will occur.
  • Going to Fast. Since you may be in a hurry or you are training for power, you might want to go fast. But, isolation exercises like the pec deck flyes are used to fatigue one muscle to stimulate growth for strength. Accordingly, if you want to develop power work that into your compound exercises.
  • Not Sqeezing. To maximize the effectiveness of this exercise you want to squeeze your chest at the fully closed position.

Variations to Pec Deck Flyes

There are two main machine types for pec deck flyes, they are the bent arm and the straight arm butterfly machine. The two other exercises that isolate your Pectoralis Major in a similar manner are dumbbell flyes and cable flyes. These exercise not exactly interchangeable since they all have different benefits (1).

Major Benefit of the Pec Deck Fly

The pec deck machine maintains constant and equal tension throughout the exercise. Since the weight, is always pulling down on the lever arms you are moving. Other flys that use the gravity of cables tension do not isolate your Pectoralis Major like the pec deck. For example in the down position for cable flyes, the tension of the cable is pulling your arms away from your body. Similarly with the dumbbell fly when your arms are straight above you, gravity is pushing them against your arms. But with the pec deck provides constant rotation force against your Pectoralis Major.

Additional Exercises that Target Your Pectoralis Major

The following exercises can be performed instead of {exercise} or to complement it.

Barbell Bench Press is the primary compound exercise that utilized your chest. Powerlifters would only be doing peck deck flyes to improve their bench press.
Dumbbell Pullovers are underutilized exercises that target your pectoralis major in a unique way that no other chest exercise can do.

Complementary and Superset Options

A very common workout split is to perform chest and triceps exercises on the same day. After you have completed the major compound exercises and you want to finish your muscles off you can do supersets of isolation exercises. Since the pec deck flyes are truely a chest isolation exercise you could do any tricep isolation exercise as a superset. Here are 5 Best Tricep Exercise you could choose from to perform a superset with the pec deck.

Building a Strong Chest

I don’t know about you but I convinced myself that I should be doing more pec deck flyes. My routines start with the major compound exercises and then perform different isolation exercises at the end. Changing up the isolation exercises not only confuses my muscles but also keeps the time at the gym more interesting and less mundane. What is your goto chest isolation exercise?

Pin peck deck flyes

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