Reactive oxygen species (ROS) are a natural byproduct
of aerobic cellular metabolism. They are highly
reactive molecules which cause oxidative damage, such
as carbonylation, to proteins, lipids and DNA. Because of
the high metabolism and energy demand of skeletal
muscle, it is especially susceptible to the carbonylation.
Thus, the level of carbonylation can be used as a
quantitative estimate of the amount of oxidative damage
to the tissue.