The Claim
Twelve weeks of linear periodized pec deck resistance training performed three times per week increases pectoralis major muscle thickness by 17–21% in untrained young men, with measurable hypertrophy observed in both the clavicular and sternocostal regions of the muscle.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
If untrained young guys do pec deck workouts three times a week for three months, following a specific plan, their chest muscles get noticeably thicker—by about 17 to 21%—in both the upper and lower parts of the chest.
See the scientific wording
Twelve weeks of linear periodized pec deck resistance training performed three times per week increases pectoralis major muscle thickness in untrained young men by 17–21%, demonstrating that this exercise can induce measurable hypertrophy in both clavicular and sternocostal regions.
What the research says
1 studyThe study looked at the same exercise, for the same amount of time and frequency, in the same type of people, and found the chest muscle got thicker by about the same amount the claim says—so it supports it.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.