Role of free radicals and antioxidant signaling in skeletal muscle health and pathology

Skeletal muscle contraction, growth, differentiation and adaptation are governed by complicated biological mechanisms still being studied intensively. Generation of reactive oxygen and nitrogen species (RS) is one of the most prominent events during contractile activity that could influence muscle function and health. While RS generation is known to cause oxidative stress, activate certain pathogenic pathways and aging, they also serve as useful signaling molecules to regulate gene expression of proteins and enzymes that play a vital role in the normal muscle function and defense against detrimental effects of RS. The purpose of the present review is two-fold: first, to provide an overview of cell signaling controlled by a redox sensitive mechanism and its impact on skeletal muscle health and function; and second, to review the various muscular diseases and disorders that have an etiological origin of RS overproduction and/or inadequate antioxidant defense. Given the physiological role of skeletal muscle we will emphasize the importance of physical exercise in promoting cellular antioxidant defense and its benefits in the maintenance of muscle health.