Skeletal and Cardiac Muscle: Similarities and Differences Jeanne Y. Wei, M.D., Ph.D. Executive Director, Donald W. Reynolds Institute on Aging; Chair, Donald W. Reynolds Department of Geriatrics; University of Arkansas for Medical Sciences; Little Rock, AR

Aging Mammalian Skeletal and Cardiac Muscle : Similarities Both are striated muscle; Both show age-related changes in performance; Both undergo atrophy in cachexic disease states; Both are improved with exercise conditioning; Both undergo inflammatory and reparative changes; Both undergo hypertrophy with resistance training; Both undergo atrophy with reduced afterload; Both have similar gene expression profiles.

Aging Mammalian Skeletal and Cardiac Muscle: Differences Aging is associated with cardiac but not skeletal muscle hypertrophy; Skeletal muscle hypertrophy correlates with improved performance, but cardiac muscle hypertrophy might cause dysfunction (HFPEF); Hypertension causes cardiac, but not skeletal muscle hypertrophy; Cardiac muscle is a syncytium; skeletal muscle is not. Cardiomyocytes have spontaneous depolarization; skeletal muscle fibers do not.