Cable fly
Flyes isolate the chest without the triceps. In a 12-week trial, untrained men who did only the pec deck, the machine version of the fly, grew both the upper and lower chest by about 17–21%; no trial has tested the cable version itself. The barbell bench press activates the chest more per set, so flyes work best alongside pressing, not instead of it.
What the science says
- The fly movement grows the chest Moderate evidence
Pinto et al. (2025) trained 15 untrained men on the pec deck for 12 weeks, from 20 down to 8 reps to failure: the upper (clavicular) chest grew about 17–18%, the lower (sternocostal) chest about 21%, and pec deck 1RM rose about 43–46%. The cable fly follows the same movement but was not tested itself.
- One hard set may be enough for beginners Limited evidence
In that trial each man trained one arm with 1 set and the other with 3 sets: growth and strength were the same. It is a single small study in untrained men, and trained lifters usually need more volume.
- Pressing activates the chest more than flyes Moderate evidence
Solstad et al. (2020) found 8–81% higher chest, front-delt and triceps activity in the barbell bench press than in dumbbell flyes at a 6-rep max in 17 trained men. Welsch et al. (2005) found similar peak activation but a shorter time under activation for flyes. Activation is not growth.
How to do it
Muscles trained: pectoralis major, anterior deltoid
- Set the pulleys at about chest to shoulder height and take a staggered stance
- Keep a soft, fixed bend in the elbows throughout
- Open the arms until you feel a stretch across the chest, without letting the shoulders roll forward
- Bring the hands together in a hugging arc
- Control the return; don't let the stack pull your arms back
How to apply it
Do flyes after your presses, with moderate loads and higher reps, taken close to failure.
Who should be careful
The stretched position puts the front of the shoulder under load; keep the range you can control and avoid heavy weights with straight arms. Persistent shoulder pain is a reason to see a physician or physical therapist.
Frequently asked questions
Do cable flyes build the chest?
The fly movement does: Pinto et al. found 17–21% chest growth from the pec deck in 12 weeks. The cable version uses the same movement but has not been tested directly.
Can flyes replace the bench press?
Not fully. Solstad et al. found the bench press activates the chest, front delts and triceps more than flyes, so flyes work best as a complement to pressing.
How many sets of flyes do I need?
Beginners may grow on just one hard set: Pinto et al. found 1 and 3 sets gave the same gains in untrained men. Trained lifters usually need more, around 2–4 sets.
Scientific references
- Pectoralis Clavicular and Sternocostal Thicknesses Increase Similarly in Response to One and Three Sets of Pec Deck Resistance Training in Untrained Young Men
- A Comparison of Muscle Activation between Barbell Bench Press and Dumbbell Flyes in Resistance-Trained Males
- Electromyographic activity of the pectoralis major and anterior deltoid muscles during three upper-body lifts
More exercises
- Back squat Strong evidence
The barbell back squat reliably builds the quadriceps, glutes and adductors and is one of the best-studied lower-body exercises in training research.
- Front squat Moderate evidence
The front squat holds the bar on the front of the shoulders, which keeps the torso more upright and loads the knees less than the back squat while recruiting the thigh muscles about as much.
- Bulgarian split squat Moderate evidence
The Bulgarian (rear-foot-elevated) split squat trains one leg at a time and builds the quads and glutes with far less load on the bar than a back squat.
- Leg press Strong evidence
The leg press builds the quadriceps about as well as free-weight squats and also grows the glutes and adductor magnus, with no balance or spinal-loading limit.
- Hack squat (machine) Moderate evidence
The machine hack squat lets you squat deep on a fixed track with your back supported, which makes it easy to push the quads close to failure.
- Romanian deadlift Moderate evidence
The Romanian deadlift is a hip hinge that loads the hamstrings and glutes at long muscle lengths, and trials of stiff-leg deadlifts and similar hip-extension exercises show real hamstring growth, mainly in the semimembranosus and biceps femoris long head.