Panels A–D, merged and single channel images of a human vastus lateralis (VL) muscle serial cross-section incubated with an antibody cocktail (BA-F8, SC-71, and 6H1). Shown are type I (blue), type IIA (strong green), type IIX (strong red and intermediate green), and type IIAX (intermediate/strong green and intermediate red) fibers. *Note that the lower intensity staining for SC-71 in type IIX fibers is indicative of non-specific cross-reactivity (see and for further details). Panels E–H, merged and single channel images of a human VL muscle serial cross-section incubated with an antibody cocktail (BA-F8, BF-35, and 6H1). Shown are type I (blue), type I and type IIA (intermediate green and strong green, respectively), type IIX (strong red), and type IIAX (intermediate/strong green and intermediate red) fibers. Panel I, human VL muscle serial cross-section showing SDH activity staining. Panel J, human VL muscle serial cross-section showing GPD activity staining. Bar represents 50 µm.