Fig 1: Endurance exercise facilitates fiber-type switching of GAS muscle in mice. Male wildtype C57BL/6 mice were fed a chow diet following endurance exercise training and harvested 8 weeks later. (A,B) The abundance of MyHC I, MyHC IIa, MyHC IIb, and MyHC IIx proteins in the GAS muscle were measured by immunoblot and analysis for trained and untrained mice. Data are reported in the bar graphs as the fold change of normalized proteins of tubulin (n = 6/group; mean ± SE). (C) The mRNA expression of MyHC I, MyHC IIa, MyHC IIb, MyHC IIx, TnnT1, TnnT3, MyoD, and MyoG in the GAS muscle via real-time qPCR. Results are reported in the bar graph as the fold changes of individual mRNAs, normalized with GAPDH (n = 4/group; mean ± SE). (D,E) Representative images and quantification of DAPI, MyHC I, MyHC IIa, and MyHC IIb via immunofluorescent staining in the GAS muscle (n = 3, Scale bar in 200 µm). Bars mean p = 0.05 analyses followed by non-paired Student’s t-test. * p < 0.05; ** p < 0.01 vs. WT-untrained.