Chest Fly Machine
- Machine
- Isolation exercise
- Chest
On the chest fly machine, also called the pec deck, you sit tall against the pad and bring the handles together in an arc in front of your chest with slightly bent elbows. It trains the chest; bend your elbows more and the triceps and front delts take over [1].
Chest
Drag to pause
- Main muscle
- Chest
- Equipment
- Chest fly machine (pec deck)
- Reps
- 12–20 for muscle building
- Sets
- 3
- Rest
- 1:30
- Weight step
- 5 kg (10 lb)
How to do it
- 1
Set the seat so the handles are at chest height.
- 2
Bring your arms together in an arc, elbows slightly bent.
- 3
Open slowly until your chest is stretched, no further.
Tempo of one rep
The figure shows a calm rep of 5.1 s with a short squeeze at the front. Tempo matters less than you’d think for growth; reps lasting 0.5 to 8 s build similar muscle [2].
Common mistakes
- Arms going too far back.
The machine then pulls your shoulder open further than your chest can follow. Open only until your upper arms are just behind your torso, no further [1].
- Bending your elbows.
The fly then turns into a press, and your triceps and front delts take over [1]. Keep your elbows slightly bent and the angle the same.
- Handles set too high.
With your hands above your shoulders, your shoulders shrug up. Set the seat so the handles are at chest height and your elbows about at shoulder height [1].
- Handles not meeting at the front.
You then skip the part where your chest contracts the most. Bring the handles all the way together and squeeze briefly [1].
Sets and reps
How Tarvo plans the chest fly machine as an isolation exercise, by goal and experience. Rest is the time between two sets.
| Goal | Reps | Rest |
|---|---|---|
| Muscle building | 12–20 | 1:30 |
| Strength | 10–15 | 1:30 |
| Both | 10–15 | 1:30 |
| Experience | Sets |
|---|---|
| New to it | 2 |
| Some experience | 3 |
| Experienced | 4 |
How Tarvo progresses your chest fly
The chest fly goes up in steps of 5 kg (10 lb), one plate on the stack. Until you reach the top of your rep range, you add one rep.
Once your first set hits the top of the range and the others are no more than two reps below it, the weight goes up by one step. Tarvo then works out from your strength how many reps you can do with the new weight; if the step is too big for that, you first add up to five reps beyond the range.
Your next chest fly
Enter what you did last time. Tarvo works out your target for the next session with the same rule as in the app.
All on target, with two left. So the same weight, one more rep.
Variations
Questions
How do you set up the chest fly machine?
Set the seat so the handles are at chest height and your elbows about at shoulder height [1]. Set the handles at the back so your upper arms are only just behind your torso in the stretch.
How many sets of chest flys for muscle growth?
Three sets of 12 to 20 reps with 1:30 min rest if you already have some experience. Together with your other chest exercises, Tarvo plans about 12 hard sets for the chest per week, a number in the range that works well [3].
Is the pec deck as good as the bench press?
For the chest, almost. In a study paid for by ACE, the pec deck reached about 98 percent of the chest activity of the bench press [4]. On push day, Tarvo plans both, with the fly after the bench press.
How far back should your arms go?
Until your upper arms are just behind your torso and you feel a stretch in your chest, no further [1].
What muscles does the chest fly machine work?
The chest, both upper and lower parts [1]. The front delts help, more so when your elbows bend more.
Sources
- [1]Legion Athletics. Pec Deck. legionathletics.com. legionathletics.comPractice article on the machine. Handles at chest height, elbows slightly bent and fixed, only slightly behind the torso at the back, fully together at the front; bending the elbows more shifts work to the triceps and front delts.
- [2]Schoenfeld, Ogborn, Krieger (2015). Effect of repetition duration during resistance training on muscle hypertrophy. Sports Med. doi 10.1007/s40279-015-0304-0Meta-analysis. Reps lasting 0.5 to 8 seconds built similar muscle; much slower reps built less.
- [3]Pelland, Remmert, Robinson, Hinson, Zourdos (2024). The Resistance Training Dose-Response: Meta-Regressions Exploring the Effects of Weekly Volume and Frequency on Muscle Hypertrophy and Strength Gain. SportRxiv (Vorabfassung). sportrxiv.orgMeta-regression of 67 studies. More sets bring more growth with diminishing returns; secondary muscles fit best counted as half.
- [4]American Council on Exercise. ACE Study Tests Common Chest Exercises, Finds Barbell Bench Press Most Effective. acefitness.org (Pressemitteilung). www.acefitness.orgPress release on a study paid for by ACE (Boehler, Porcari), second-hand. The pec deck reached about 98 percent of the chest activity of the bench press.
Keep going
Tarvo sets your next chest fly target.
From your last session, set by set. You just check them off.
One email when Tarvo launches. Nothing else. Privacy
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