Redox Systems, Antioxidants and Sarcopenia.

According to the free-radical theory of aging, oxidative stress is a key contributor to the onset of age-related conditions by inducing structural and functional alterations in several cellular components. Although innate defenses exist for limiting the occurrence of such detrimental effects, their ability to counteract the continuous and large production of reactive oxygen species becomes increasingly inefficient with aging. In this context, interventions aimed at preserving the homeostatic balance between oxidant production and antioxidant protection may be beneficial on the pathophysiological modifications and clinical manifestations featuring the aging process. Sarcopenia is a clinical condition defined as the progressive age-related loss of muscle mass and function. In particular, a reduction of motor units and wasting of muscle fibers occurs during the aging process and negatively affects muscle quality. The biological mechanisms responsible for sarcopenia are complex, multifactorial and closely related to those characterizing the aging process. Among these, a pronounced unbalance between pro-oxidant and antioxidant species may play a major role. This review paper presents and discusses the possible role of the oxidant/antioxidant systems in the determination and development of the sarcopenic phenotype. Special attention will be devoted to the contribution of antioxidant agents in the maintenance of the homeostatic equilibrium for the organismal protection against the onset of age-related conditions. However, despite their popularity as beneficial compounds, there is no clear evidence in the literature about the protective effect of antioxidant supplements usage. Therefore, further research is needed to address and clarify such ambiguity.