Free Radicals and Human Aging Muscle

Aging is an inevitable biological process, characterized by a general decline in
physiological and biochemical functions of the major systems. In the case of the
24 neuromuscular system, reductions in strength and mobility cause a deterioration
25 in motor performance, impaired mobility, and disability. At the cellular level,
aging is caused by a progressive decline in mitochondrial function that results in
accumulation of reactive oxygen species (ROS). As the level of oxidative stress
28 in skeletal muscle increases with age, age process is characterized by an imbalance between an increase in ROS production in the organism and antiox-
idant defenses as a whole. The goal of this chapter is to examine the results of
existing studies on oxidative stress in aging human skeletal muscles, taking into
account (I) different physiological factors, such as sex, fiber composition,
muscle type, and function; (II) biochemical alterations in muscle induced by
ROS; and (III) oxidative stress markers related to aged muscle, particularly
8-hydroxy-20-deoxyguanosine (8-OHdG), malondialdehyde (MDA), and levels
of carbonyl residues such as in Carbonyl Proteins (PC). Finally, we analyze data,
present in literature, regarding the beneficial effects of nutrition and physical
activity in preventing oxidative damages associated with sarcopenia.