There is a lot of evidence demonstrating that physical activity is going along with an increased production of oxygen derived free radicals (reactive oxygen speces, ROS). Regarding the 'short term' mediated ROS effects, it has been shown recently that endogenously produced ROS, possibly H2O2 or its derivatives, play an important role for example in contraction-mediated activation of glucose transport in fast-twitch muscle

As an adaptive, 'longterm' response towards the exercise-induced ROS-generation, muscle antioxidant defense systems are upregulated after heavy exercise. This may be due to an activation of NF-kappaB signaling cascade, which has been shown to enhance the gene expression of important enzymes, such as mitochondrial superoxide dismutase or the nitric oxide synthases. In addition, MAPK activations are involved in a variety of cellular functions including growth, proliferation, and adaptation.

Therefore, a broader knowledge on the subcellular mechanisms underlying exercise-induced ROS-signaling is important for high performance exercise and in the field of medical prevention and rehaboilitation.