Can antioxidants protect against disuse muscle atrophy?

Long periods of skeletal muscle inactivity (e.g. prolonged bed rest or limb immobilization) results in a loss of muscle protein and fibre atrophy. This disuse-induced muscle atrophy is due to both a decrease in protein synthesis and increased protein breakdown. Although numerous factors contribute to the regulation of the rates of protein breakdown and synthesis in skeletal muscle, it has been established that prolonged muscle inactivity results in increased radical production in the inactive muscle fibres. Further, this increase in radical production plays an important role in the regulation of redox-sensitive signalling pathways that regulate both protein synthesis and proteolysis in skeletal muscle. Indeed, it was suggested over 20 years ago that antioxidant supplementation has the potential to protect skeletal muscles against inactivity-induced fibre atrophy. Since this original proposal, experimental evidence has implied that a few compounds with antioxidant properties are capable of delaying inactivity-induced muscle atrophy. The objective of this review is to discuss the role that radicals play in the regulation of inactivity-induced skeletal muscle atrophy and to provide an analysis of the recent literature indicating that specific antioxidants have the potential to defer disuse muscle atrophy.