Measurement of muscle morphology and satellite cell activation. Muscle morphology will be determined using immunohistochemical techniques. Muscle fiber cross sectional area (CSA), proportion, and assessment of intramuscular oxidative enzyme content, glycolytic enzyme content, and lipid content will be determined using standard methods. Tissue sections will be cut at 10 μm thickness in a cryostat maintained at 25ºC, mounted on Fisherbrand Superfrost®/Plus microscope slides (Fisher Scientific, USA). Satellite cell content will be determined using anti-CD56 antibody directed against the neural cell adhesion molecule (NCAM) (identical to the Leu 19 antigen) [Clone MOC-1, (DakoCytomation, Carpinteria, CA) and Pax7. For muscle cell boundary polyclonal rabbit anti-laminin antibody directed against laminin (extracellular matrix protein) (DakoCytomation) will be utilized. Fiber typing will be accomplished with anti-Myosin Heavy Chain-slow (MyHC-slow, Sigma, St. Louis, MO). Nuclear marker 4', 6-diamidino-2-phenylindole, dihydrochloride (DAPI; Molecular Probes) will be used to localize DNA (nuclei). Digital images will be captured on a Zeiss Axio-Cam Epi-Fluoroscent microscope and analyzed using the Zeiss AV4 software.