sActRIIB-mFc treated +/G610C mice Gast muscle had reduced specific tetanic force [specific Po (Peak Po/Muscle myofiber CSA)] as compared to vehicle treated counterparts (B). sActRIIB-mFc treated male WT and +/G610C mice TA muscle had reduced specific Po as compared to vehicle treated counterparts (C). (A) Sol Specific Po, (B) Gast Specific Po, and (C) TA Specific Po of 4 months old WT, +/G610C, and oim/oim vehicle (solid bars: control) and sActRIIB-mFc (open bars) treated mice. (n=9–12 per groups; TA muscle groups are n=4–7). The genotype main effect was evaluated. Gast and Sol values are the LSmeans±SE of the combined genotype values regardless of sex, and the TA exhibited a genotype × sex interaction, and the values are LSmeans±SE separated by sex and genotype. *p<0.05; †p<0.05 vs. WT+vehicle treated mice.