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Pectoralis Major (Chest)

Pectoralis major: where it is, what it does, and the 4 exercises on this site that train it.

Pectoralis major highlighted, with muscles it works alongside in a lighter tint.

Exercises

Flat Chest Press

Where it is and what it does

TODO(content)Origin, insertion, parts and joint actions wait for a reviewed muscle research doc (docs/research/muscles/pectoralis-major.md) citing a verified anatomy source. The OpenStax Anatomy and Physiology entry (S025) is still marked “To verify”.

Nerve supply

TODO(content)Innervation to be added from the verified anatomy source.

How flat pressing trains it

The pectoralis major is the prime mover in every flat chest press on this site. Its sternocostal (mid and lower) part is most active when you press on a flat bench, compared with incline or decline angles [1, 2], while its clavicular (upper) part contributes in every flat press and works more as the bench inclines; upper-chest activity peaked around 30° in one study of trained adults [1].

Measured chest activity was similar for barbell, dumbbell and Smith machine presses, even though maximal loads differed [3]. Grip width shifts the work: narrowing the grip on a bench press increased triceps activity and decreased sternocostal activity [4]. Higher measured activity does not by itself mean more growth, so treat these as notes on how each press loads the muscle, not as a ranking.

Common problems

TODO(content)Brief, non-diagnostic notes on common problems wait for the muscle research doc. If you have pain in this area, see a doctor or physiotherapist.

Works alongside

How sure are we

ClaimCertaintyBasis
The sternocostal part is most active in flat pressing; the clavicular part works more as the bench inclines.Moderate[1, 2]
Barbell, dumbbell and Smith machine presses produce similar measured chest activity.Moderate[3]
A narrower bench grip reduces sternocostal chest activity and increases triceps activity.Moderate[4]

Sources

  1. Rodríguez-Ridao D, Antequera-Vique JA, Martín-Fuentes I, Muyor JM. Effect of five bench inclinations on the electromyographic activity of the pectoralis major, anterior deltoid, and triceps brachii during the bench press exercise. Int J Environ Res Public Health. 2020;17(19):7339. doi:10.3390/ijerph17197339Verified · checked 22 Oct 2026
  2. Barnett C, Kippers V, Turner P. Effects of variations of the bench press exercise on the EMG activity of five shoulder muscles. J Strength Cond Res. 1995;9(4):222–227. Finding checked via a secondary source · checked 22 Oct 2026
  3. Saeterbakken AH, van den Tillaar R, Fimland MS. A comparison of muscle activity and 1-RM strength of three chest-press exercises with different stability requirements. J Sports Sci. 2011;29(5):533–538. Cristin recordVerified · checked 22 Oct 2026
  4. Lehman GJ. The influence of grip width and forearm pronation/supination on upper-body myoelectric activity during the flat bench press. J Strength Cond Res. 2005;19(3):587–591. PubMed 16095407Finding checked via a secondary source · checked 22 Oct 2026

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