Pec Deck
chest
What moves the load, and what it costs
3.5MET
Chest is the prime mover, with the front deltoid assisting. The most controlled chest isolation available, and the easiest to take safely to failure. There is no balance to lose and no dumbbells to drop.
Cue: Set the seat so the handles are at chest height and your upper arms sit parallel to the floor.
Written on other cards as: Machine fly · Butterfly machine
ਸਰੋਤ·2024 Adult Compendium of Physical Activities·FILED UNDER WEIGHTS, 8–15 REPS·ਸਮੀਖਿਆ ਜੁਲਾਈ 2026
SHARED AXIS · SEVEN VALUES FROM ONE TABLE · HIGHLIGHTED ROW IS THIS MOVEMENT
The compendium files pec deck under a category, not a lift. Read the ladder as position, not precision: this is heavier work than sitting quietly by a factor of 3.5, and middling for conditioning work.
Turning that MET value into a real energy cost
- Map the movement to a published category. The compendium measures categories of conditioning work, never individual lifts, so pec deck is filed under Resistance training (weight lifting), multiple exercises, 8–15 repetitions at varied resistance.
- Take the category's MET value — 3.5. One MET is the cost of sitting quietly, so this is 3.5 times resting metabolism.
- Multiply by 3.5 to get millilitres of oxygen per kilogram per minute, the unit the MET is actually defined in.
- Multiply by your bodyweight in kilograms and divide by 200. The result is kilocalories per minute of work.
- Count working minutes only. Under load, not under the roof — a set of eight is about 25 seconds of the hour you were there.
kcal/min = MET × 3.5 × body mass (kg) ÷ 200 Pec Deck: 3.5 × 3.5 × 70 ÷ 200 = 4.29 kcal/min
ਸਰੋਤ·ACSM metabolic equation + 2024 Adult Compendium of Physical Activities·REFERENCE BODY MASS 70 KG·ਸਮੀਖਿਆ ਜੁਲਾਈ 2026
What is actually doing the work
| Muscle | Role | What it does here |
|---|---|---|
| ChestPectoralis major | Prime mover | Brings the upper arm across the body and forward (shoulder horizontal adduction and flexion). The clavicular head contributes more when the arm travels up and in; the sternal head when it travels down and in. |
| Front deltoidAnterior deltoid | Synergist / stabiliser | Raises the arm to the front (shoulder flexion) and assists horizontal adduction. Prime mover in overhead pressing, heavy synergist in every bench press. |
The prime mover produces the movement against the resistance; synergists assist and stabilisers hold a joint still without moving it. An exercise trains the whole muscle it loads — there is no way to work only part of a muscle, and no exercise removes fat from the area around it.
Set up, then earn the rep
Machine. Every rep should look like the first one. The moment it stops looking like the first one, the set is finished.
PATTERN · ISOLATION
- Set up with the handles out at chest height, shoulder blades pulled down and back.
- Fix a slight bend in the elbows and keep that exact angle for the whole set — the elbows do not open or close, only the shoulders move.
- Set the seat so the handles are at chest height and your upper arms sit parallel to the floor.
- Open the arms in a wide arc until you feel a strong stretch across the chest, without the shoulders rolling forward.
- Bring them back together along the same arc, squeezing the chest at the finish.
- Stop the set when the elbow angle starts changing — at that point it has become a bad press.
Where this one breaks down
Not theory. These are the faults you correct on a gym floor, and the correction that actually works.
Bending and straightening the elbows.
That turns the fly into a weak press and takes tension off the chest. Lock the elbow angle and let the shoulder do all the work.
Going too heavy.
The fly has a long lever and a nasty stretched position. It is a light exercise by design; the press is where the load goes.
Shoulders rolling forward at the bottom.
Keep the blades pinned back so the stretch happens in the chest, not the front of the shoulder capsule.
Regress it, or progress it
Regress — earn it first
Nothing on this site regresses it further: this is already near the entry point of its pattern. Take load off, shorten the range, or slow the tempo — in that order.
Prescription: load, reps, rest
Read off the goal, then hold the technique constant as the load climbs. Derived from the movement's mechanics, not invented for this page: a single-joint movement does its best work in moderate to high reps — very low reps load the joint before the muscle.
| Goal | Sets | Reps | Rest | Notes |
|---|---|---|---|---|
| Strength | 3–4 | 6–10 | 2 ਮਿੰਟ | Single-joint work responds poorly to very low reps — the joint gets the load before the muscle does. |
| Muscle size | 3–4 | 10–15 | 60–90 sec | This is where isolation work earns its place: cheap volume for one muscle, little systemic fatigue. |
| Endurance / fat loss | 2–3 | 15–25 | 30–45 sec | High reps here are genuinely useful — the load is small enough that form survives the fatigue. |
| First month | 2 | 12–15 | 60 sec | Light. Isolation work is for adding volume later, not for building a base. |
Time under load, in kilocalories
Read these as minutes of work, not minutes in the building. A set of eight takes about twenty-five seconds; the rest of the hour is rest, chalk and queueing.
Mapped category: Resistance training (weight lifting), multiple exercises, 8–15 repetitions at varied resistance — 3.5 MET. That is the published category this movement is filed under, not a measurement of this specific lift.
Worked at 3.5 MET × 3.5 × 70 kg ÷ 200 = 4.29 kcal per working minute for a 70 kg adult. Scale it by your own bodyweight; the equation is linear. The full activity dataset lives at BurnLab.
ਸਰੋਤ·2024 Adult Compendium of Physical Activities·CATEGORY VALUE, NOT A PER-EXERCISE MEASUREMENT·ਸਮੀਖਿਆ ਜੁਲਾਈ 2026
If the rack is taken
Substitutes train the same prime mover through the same pattern with different kit. Computed from the muscle and pattern data on this card, not hand-picked to fill a grid.
Nothing at all to hand: Knee Push-Up is the closest match — same prime mover, same pattern, no kit.
Where it sits in a week
One movement is not a programme. The twelve templates put these in order, including 6 that need no gym at all.
The questions that come up on the floor
What muscles does the pec deck work?
Pec Deck is a single-joint isolation movement in which the chest is the prime mover, assisted by the front deltoid. Brings the upper arm across the body and forward (shoulder horizontal adduction and flexion). The clavicular head contributes more when the arm travels up and in; the sternal head when it travels down and in.
Is the pec deck good for beginners?
ਹਾਂ। ਇਸ ਸਾਈਟ ਉੱਤੇ ਤਕਨੀਕੀ ਔਖਿਆਈ ਵਿੱਚ ਇਸਨੂੰ 5 ਵਿੱਚੋਂ 1 ਦਰਜਾ ਮਿਲਿਆ ਹੈ — ਬਿਨਾਂ ਕੋਚਿੰਗ ਦੇ ਇੱਕੋ ਸੈਸ਼ਨ ਵਿੱਚ ਸਿੱਖਣਯੋਗ। ਸਭ ਤੋਂ ਹਲਕੇ ਸਮਝਦਾਰ ਭਾਰ ਅਤੇ 12–15 ਦੇ ਦੋ ਜਾਂ ਤਿੰਨ ਸੈੱਟਾਂ ਨਾਲ ਸ਼ੁਰੂ ਕਰੋ।
What can I do instead of the pec deck at home?
The closest no-equipment substitute is the knee push-up, which trains the same prime mover through the same movement pattern. If you own a little equipment, the resistance band fly is closer still. It will not load you as heavily, so use higher reps and slower tempo to make up the difference.
How many sets and reps of the pec deck should I do?
For muscle size, 3–4 sets of 10–15 with 60–90 sec rest. For strength, 3–4 sets of 6–10 with 2 min rest. In your first month, 2 sets of 12–15, stopping well short of failure. Total weekly hard sets per muscle group matters more than the exact rep number in any of these ranges.
Does the pec deck burn fat from the chest?
No. No exercise removes fat from the area it trains — spot reduction has been tested repeatedly and does not happen. Training the chest builds the muscle underneath; where body fat is lost from is decided by an overall calorie deficit and by your genetics, not by which exercise you chose.
Muscle roles follow standard kinesiology references and are described by joint action rather than by gym convention — see how this site is built. Energy figures are derived from the 2024 Adult Compendium of Physical Activities. Every reference is named and dated on the sources page. General information only — not medical or coaching advice. Load, form and progression should be adjusted to your own experience and any injury history. When in doubt, get coached in person.
ਸਰੋਤ·Published exercise references·MUSCLE ROLES ASSIGNED BY JOINT ACTION·ਸਮੀਖਿਆ ਜੁਲਾਈ 2026
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