Pec Deck
A chest fly on a machine: the fixed path lets you isolate your pecs and push close to failure safely.
Also known as: pec deck fly, butterfly machine, machine fly
- Level
- Beginner
- Equipment
- Pec Deck
- Type
- Isolation
Muscles worked
PrimaryChestChest exercises
SecondaryFront DeltsShoulder exercises
SecondarySerratus
How to do it
- Adjust the seat so the handles are at chest height and your arms are nearly parallel to the floor.
- Sit with your back against the pad and grab the handles with a slight bend in your elbows.
- Bring your arms together in front of your chest, squeezing your pecs.
- Return slowly to a stretch without letting the weight stack rest.
Form cues
- Keep your chest up and shoulder blades back throughout.
- Your elbows drive the movement; your hands just hold on.
- Pause for a second with your arms together.
Common mistakes
- Seat too high or too low: your shoulders end up doing the work. Your arms should line up with your chest.
- Leaning off the backrest as you close: you lose the isolation.
- Opening too far back: it stresses the shoulder. Stop at the stretch.
Sets and reps
3 sets of 10-15 reps, the last close to failure, with 60-90 seconds of rest. It works great at the end of a chest workout.
Variations
Same movement, different equipment. Pick based on what you have and what you want from the pec deck.
Machine chest fly
The same idea with long handles instead of forearm pads.
How to do it
- Sit in the chest fly machine and adjust the seat so the handles align with your chest.
- Grip the handles with a slight bend in your elbows.
- Bring the handles together in front of your chest in a smooth arc.
- Squeeze your pectorals at the point of peak contraction.
- Return under control to the starting position without slamming the weight.
- Primary
- Chest
- Secondary
- Front Delts, Serratus
FAQ
Does the pec deck build chest?
Yes: it isolates the pecs with little risk and lets you stack quality sets close to failure, which is key for growth.
Pec deck or cable flyes?
They're very similar. The pec deck is more stable and simpler; cables let you change angles.
Can I use it for rear delts?
Yes, many pec decks let you sit facing the pad and open your arms backward to train the rear delts.
What muscles do the pec deck work?
They mainly work the chest, with help from the front delts and the serratus.
Add the pec deck to your next workout
Log your sets and weights, and see how each muscle progresses in the app.
