More good stuff from the Source: Redox Report

Superoxide is biologically quite toxic and is deployed by the immune system to kill invading microorganisms, which is good. This is why a bit of exercise is good. It stresses the immune system. But, the hard core athletes among us can overdo a good thing. Superoxide is a byproduct of mitochondrial respiration and it can be inimical cellular health in high concentrations, such as during intense and prolonged exercise. On to the study.

The abstract: Acute exercise increases expression of extracellular superoxide dismutase in skeletal muscle and the aorta.

Exercise dramatically increases oxygen consumption and causes oxidative stress. Superoxide dismutase (SOD) is important in the first-line defence mechanisms against oxidative stress. To investigate the effect of acute exercise on the expression of SOD, we examined the expression of mRNA for three SOD isozymes, in mice run on a treadmill to exhaustion. Six hours after exercise, the expression of extracellular SOD (EC-SOD) mRNA increased significantly in skeletal muscle and persisted for 24 h, whereas no change was observed for cytoplasmic and mitochondrial SOD mRNA. Moreover, acute exercise also induced EC-SOD mRNA in the aorta. These results suggest that a single bout of exercise is enough to augment the expression EC-SOD mRNA in skeletal muscle and the aorta, and may partly explain the beneficial effect of exercise.

Redox Report(Volume 13, Number 5, October 2008 , pp. 213-216(4))