Muscle fiber proteomics reveals sex- and fiber type-specific adaptations to resistance training

Skeletal muscle hypertrophy is a hallmark of resistance training that positively impacts health and longevity. However, despite physiological differences between sexes and fiber types, the underlying proteome changes with resistance training have not been studied in a sex- and fiber type-specific manner. Herein, we show sex differences in the fiber type-specific proteome, predominantly in type II fibers. Following 8 weeks of resistance training, substantial remodeling of the human skeletal muscle proteome occurred in a sex- and fiber type-specific manner. Notably, type II fibers exhibited much greater adaptations across both sexes, whereas the main sex-difference was a greater remodeling of intermediate filaments in females. In addition, baseline abundance of proteins involved in translation was highly correlated with fiber hypertrophy, and differed between sexes and fiber types. Thus, translational capacity may partially explain differences in resistance training-induced hypertrophy. Our findings demonstrate key aspects of sex- and fiber type differences in muscle physiology and their contributions to resistance training-induced adaptions.