Pec Deck Chest Fly

Also known as: Pec Deck Fly, Butterfly Machine, Pec Fly

StrengthPush

Track Pec Deck Chest Fly in SmartWorkout and watch your numbers go up

Log sets, weights and progress for free, with no workout limits.

Body Part: Chest

Description

Sit with your back on the pec deck, forearms against the pads, and squeeze the pads together in front of your chest to build your pecs. Your elbows stay bent at about 90° and your hands only rest on the handles, so your forearms do the pushing, not your grip. The whole chest works, the middle near the breastbone hardest, while the front delts help only a little. The short lever and the backrest make it easy to learn and easy on the elbows, so many lifters use it to finish chest day after presses.

How to Perform

Set the seat so that, sitting tall, your elbows are level with your shoulders or slightly below and your shoulders sit right under the machine's pivots.
Before you sit, set the start-position adjuster, if there is one, so your elbows open only to the line of your body. Pick the weight now too.
Sit with your back and shoulder blades flat on the backrest, chest up, and feet flat on the floor a little wider than your hips.
Put your forearms upright against the pads with your elbows at the bottom end, bent about 90°. Your hands just rest on the top handles.
Breathe out and drive your elbows toward the middle of your chest until the pads touch. Squeeze for a second while your upper back stays on the backrest.
Breathe in as the pads open over about 2 seconds, back to the line of your body with a stretch across your chest. Keep the stack off its rest until the last rep.

What Muscles Work

Primary Muscle:

Secondary Muscles:

Tips

Do 2–4 sets of 10–15 reps, sometimes up to 20, stopping 0–2 reps short of failure. Sets heavier than about 8–10 reps rarely pay off on this machine.
Add reps at the same weight until you get 15 on every set with the pads touching, a one-second squeeze and a 2-second return. Then move the pin down one plate (usually 2.5–5 kg) and work up again from 10. If a plate is too big a jump, use the add-on weight or hold the squeeze longer first.
The chest does the work: near the breastbone as the pads meet, and as a stretch toward your armpits when they open. Tired forearms or fingers mean you're pushing with your hands. A pinch at the front of the shoulder in the open position means the arms open too far or the seat is at the wrong height, so fix that before you add weight.
New to the machine? Use a light weight and set the start so your elbows open only to a hand's width in front of your body, then widen it as the movement gets familiar. Once the full range feels easy, make the same weight harder with a 3-second return and a one-second pause in the stretch.
Substitutes: Machine Chest Fly if your machine has handles and long arms instead of pads, Seated Cable Fly as the closest cable version with back support, Cable Middle Chest Fly for constant tension over a longer arc, and Dumbbell Chest Fly when all you have is dumbbells. Machine Reverse Flyes are a different exercise: you sit facing the backrest of a similar (often combination) machine and open your arms backward.

Common Mistakes

Pushing with your hands: a tight grip, bent wrists, forearms drifting off the pads. Hold the handles loosely, or open your hands, and press through your forearms and elbows.
Elbows sliding down the pads until the fly turns into a press and the front of your shoulder takes over. Set the seat so your upper arms are close to level, and keep your elbows at the bottom of the pads at the same height on every rep.
Rounding your shoulders off the backrest to make the pads meet. Your upper back and shoulder blades stay on the pad; if the pads won't touch that way, the weight is too heavy.
Opening too far or bouncing out of the stretch until the front of the shoulder pinches. Set the start so your elbows stop in line with your body, and turn around slowly at the open end.
Slamming the pads together, leaning back and letting the stack crash between reps. Go lighter and count it out: about 1.5 seconds in, a one-second squeeze, 2 seconds out.