What is Oxidative Stress?

free radicalsOxidative stress is the imbalance between reactive oxygen species (ROS) and the antioxidant systems. ROS are produced by the mitochondrial respiratory chain and they damage cellular components such as proteins, lipids and DNA, potentially resulting in a loss of function of some physiological processes, in addition to an increase of the inflammatory status. To counteract these harmful effects, the body has a mechanism of defence and repair, known as the antioxidant systems. These are represented by several proteins, that neutralize ROS by enzymatic or non-enzymatic mechanism. Given the link between ROS and chronic inflammation, it is not surprising that oxidative stress is associated with the onset of different clinical conditions, such as atherosclerosis, cancer, Type 2 Diabetes Mellitus and some neurological diseases. There are some biochemical markers of lipid peroxidation, protein oxidation and DNA damage that allow us to quantify the oxidative stress and to describe its relationship with exercise.

What are the consequences of oxidative stress? Is it measurable?

There is an acute increase in ROS production during physical exercise, if the stimulus is repeated, it leads to adaptions such as the up-regulation of antioxidant enzymes (e.g. glutathione synthase and superoxide dismutase) and an increase in the number of mitochondria, that allows lower levels of respiratory activity for the same degree of energy production. For this reasons, there is strong scientific evidence about the role played by exercise in both counteracting and reducing the oxidative stress. This antioxidant role could be one of the beneficial mechanisms of exercise in attenuating ageing, improving the lipid profile, improving insulin sensitivity and reducing endothelial dysfunction.

Which is the most antioxidant type of exercise?

There is not a single kind of exercise that is effective in counteracting oxidative stress. Indeed, both aerobic and resistance training, or a combination of both are effective in stimulating the physiological adaptations allowing a faster clearance of ROS while exercising and a reduced production at rest. It is noteworthy as strenuous physical exertion could be deleterious because of an excessive production of ROS, that could overwhelm the antioxidant capacity.