Fly
Pec deck fly
Works
Also works
Equipment
How to do it
- Sit at the pec deck with your back against the pad.
- Grip the handles with your arms open and a slight elbow bend.
- Bring the handles together in front by contracting your chest.
- Squeeze your chest as you bring them together without shrugging.
- Return under control until you feel the stretch, without slamming the stack.
Common mistakes
- Shrugging the shoulders when bringing together
- Using momentum to move the load
- Cutting the range without stretching
What the evidence says
Comparing dumbbell flyes against barbell bench press at 6-rep-max loads, the press showed higher pectoralis, anterior deltoid and triceps activation than the fly across most phases of the movement (8% to 81% more). The fly is not "more chest" than the press: it's a different thing, with less triceps involved.
Solstad TE, Andersen V, Shaw M, Hoel EM, Vonheim A, Saeterbakken AH. «A Comparison of Muscle Activation between Barbell Bench Press and Dumbbell Flyes in Resistance-Trained Males». Journal of Sports Science and Medicine, 2020. View the study
Twelve weeks of pec deck training in untrained men: both the clavicular portion (17–18%) and the sternocostal portion (21%) of the pectoralis thickened, and one set per session matched three. The flat fly is not a "lower chest" exercise: the upper portion works too.
Pinto MD, Ughini C, Nunes JP, Cadore EL, Pinto RS. «Pectoralis Clavicular and Sternocostal Thicknesses Increase Similarly in Response to One and Three Sets of Pec Deck Resistance Training in Untrained Young Men». Journal of Strength and Conditioning Research, 2025. View the study
The case for the fly is the stretched position. In the range-of-motion meta-analysis, full ROM beat partial ROM by a trivial margin on average, but when the partial was performed at long muscle lengths the trend reversed in favour of the partial for hypertrophy — with wide uncertainty around the estimate. Applied to the fly: if you have to cut range, cut it at the top, never at the bottom.
Wolf M, Androulakis-Korakakis P, Fisher J, Schoenfeld B, Steele J. «Partial Vs Full Range of Motion Resistance Training: A Systematic Review and Meta-Analysis». International Journal of Strength and Conditioning, 2023. View the study
What isn't settled: The central question is missing: no training study has compared flyes against pressing for pectoralis growth, nor measured whether adding flyes to a routine that already presses contributes anything. The other open question — whether resistance should peak at the stretch (dumbbell, low cable) or at the squeeze — has a single MRI trial finding no difference, but it remains an unreviewed preprint, so we're not counting it yet.
Other variations
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