Pectoralis Clavicular and Sternocostal Thicknesses Increase Similarly in Response to One and Three Sets of Pec Deck Resistance Training in Untrained Young Men.

Abstract: Pinto, MD, Ughini, C, Nunes, JP, Cadore, EL, and 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. J Strength Cond Res 39(5): 523-530, 2025-Perceived lack of time is a commonly cited reason for not engaging in resistance training (RT). Consequently, there is interest in identifying time-efficient and minimum-effective RT doses. Although RT and rehabilitation programs typically aim for muscle-specific growth, research on the pectoralis major is notably limited despite it being a frequently targeted muscle group. Here we compare the effects of two RT volumes on regional pectoralis major hypertrophy and shoulder horizontal abduction strength using a within-subject design. Following a non-training control period, 15 untrained young men (age: 24.1 ± 3.1 years) participated in a 12-week RT program, comprised of the pec deck exercise, performed in 1 set (1S) vs. 3 sets (3S), in a linear periodization of 20 to 8 repetitions maximum to failure. B-mode ultrasound imaging was used to analyze muscle thicknesses of the pectoralis major clavicular and sternocostal portions, and maximal strength was determined by 1-repetition maximum tests on the pec deck exercise. After 12 weeks of RT, similar increases were observed between conditions for the pectoralis major clavicular (1S = 17%; 3S = 18%) and sternocostal (1S = 21%; 3S = 21%) thicknesses, and maximum strength (1S = 46%; 3S = 43%). Our results indicate no effect of RT volume (1S vs. 3S) on changes in muscle size and strength and do not support regional hypertrophy after pec deck exercise in untrained men. These results have important implications for RT prescription and rehabilitation practices for individuals who may have limited time or those undergoing brief rehabilitation sessions targeting the pectoralis musculature.