Pec Dec

What is the pec dec?

The pec dec is an isolation machine to exercise the chest, where the exerciser bring two pads together in front of their chest.

What muscles does the pec dec use?

The pec dec uses the chest muscles (pectoralis major) and also gets some help from the synergist muscle of the front shoulder (anterior deltoids). Despite the shoulder involvement, this lift is considered an isolation exercise targeting the chest.

Benefits of the pec dec

The pec dec is a great exercise for the chest, particularly when used as a final part of your chest workout routine.

Because this is an isolation exercise, it is best used after compound chest exercises, such as the bench press. In this way, the pec dec can work to isolate the chest muscles and is ideal for those looking to fine tune their chest definition.


You can isolate different parts of the chest more depending on the height of the seat on the machine. Sitting higher targets the lower chest, while sitting lower targets the higher chest.

The pec dec machine is sometimes called the butterfly machine or the chest fly machine. It is an excellent finishing exercise after a chest workout to isolate the chest muscles.

However, it is best to use the pec dec in tandem with the chest press or bench press to enjoy a fuller compound workout for the whole chest area.

Pec dec exercise

Pec dec stance

To prepare to use the pec dec machine, sit so that your feet are flat on the floor. Your upper arms should be parallel to the floor when your elbows are on the pads and your hands are gripping the handles.

Elbows should be just behind the shoulders. Be careful not to over-extend the shoulders to reach back – always use the foot pedal to help bring the pads forward. This is very important for safety.

Performing the pec dec exercise

To perform your first rep, draw the elbows in front of your body to bring the pads together and lift the weight as you exhale. Make sure the pressure comes from leading with the elbows not the hands.

Pause when the pads come together, then slowly let the pads move back again, finishing in line with your shoulders and not behind them.

Your hips, back and shoulders should remain in contact with the back rest throughout the movement with abdominals engaged and a neutral spine.

Once you have finished your last rep, gently return the weight to the stack with the help of the foot pedal, releasing one arm at a time.

Safety and the pec dec 

There has been some controversy over the pec dec machine with some exercisers concerned that it has the potential to damage the shoulders.

However, with careful use, using slow and controlled movements and proper form, the pec dec can be an excellent isolation exercise for the chest and a great way to target the muscles at the end of a workout.


Always be sure to pay special attention to form when using this machine, as good technique will reduce the risk of injury.

Remember to use the foot pedal to bring the pads forward and never over-extend your shoulders by reaching back. This is also important at the end of the exercise, using the pedal to help guide the pads back as you release the weight back onto the stack.

Explore more chest exercises with the bench press compound lift, press ups bodyweight exercise and flyes isolation lift.

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