Human skeletal muscle aging and the oxidative system: cellular events.

As we age, the aerobic and functional capacities of our major physiological systems progressively decline. In the case of the neuromuscular system, reductions in strength and mobility cause a deterioration in motor performance and in turn a greater tendency to fall (with increased risk of fractures), impaired mobility, disability and loss of independence in the elderly. Given the increase in our life expectancy and the consequent growth in the elderly population, these conditions will have an increasing impact on modern healthcare systems, and their prevention and attenuation needs to be addressed. Several intervention strategies have been used to improve motor performance among the aging. At the cellular level, aging is caused by a progressive decline in mitochondrial function that results in the accumulation of reactive oxygen species (ROS) generated by the addition of a single electron to the oxygen molecule As the level of oxidative stress in skeletal muscle increases with age, the production of some antioxidant enzymes increases adaptively to compensate in part. The aging process is characterized by an imbalance between an increase in the production of reactive oxygen species in the organism and the antioxidant defences as a whole. The goal of this review is to examine the results of existing studies on oxidative stress in aging human skeletal muscles, taking into account different physiological factors (sex, fiber composition, muscle type and function).