Fig 1.

(A-D) Immunofluorescence staining for fast (A, C) and slow (B, D) myosin heavy chain (MHC) proteins in serial sections of biopsies from sedentary seniors (A, B) and physically active seniors (C, D). White arrows point to small angulated muscle fibers; white circles surround the central fibers that delineate fiber-type groupings. Note that the clustered fibers in the biopsies of the sedentary seniors are of the fast type, whereas those of the physically active seniors are of the slow type. Figure redrawn from Mosole S, et al. J Neuropathol Exp Neurol. 2014 Apr;73(4):284-94.⁴