All sections were inspected under a microscope (PrimoStar, Carl Zeiss MicroImaging, Germany) and photographed using a CMOS camera. Fibers were classified as types I, IIa and IIx according to the intensity profile of the ATPase, NADH and immunohistochemical stained sections. Hybrid fibers were disregarded as they represented less than 1% of the total number of fibers analyzed.