Muscle fatigue and induction of stress protein genes: A dual function of reactive oxygen species?

Definitive characterization of the mechanisms of skeletal muscle fatigue is still an area of active investigation. One emerging theory concerns a role for the reactive oxygen species (ROS) produced primarily as a consequence of elevated rates of mitochondrial respiration. It has been theorized that the long-lasting effects of low-frequency fatigue (LFF) can be attributed to disruption of some stage of the excitation contraction coupling (ECC) process. Recent evidence suggests that ROS likely denature one or more proteins directly associated with the sarcoplasmic reticulum (SR) Ca2+ release mechanism. Given the potential of ROS to damage intracellular proteins during subsequent bouts of muscle contractions, the capacity of preexisting antioxidant pathways may be complemented by the synthesis of inducible heat-stress proteins (HSPs). HSPs collectively function to maintain cellular protein conformation during stressful proteotoxic insults. The goal of this article is to illustrate how recent findings suggest a dual role of ROS generated during muscle contractions.