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Exercise and Free Radicals Formation

It is a generally accepted fact that exercise is good for our health. However, its wide-ranging health benefits are being partially offset by a dramatic increase in free radical activity in the body. This rise in free radical formation is directly linked to the increase in physical activity. Free radicals are unstable substances and their excess production is involved in a multitude of ailments, including cardiovascular, autoimmune and neurodegenerative diseases as well as cancer, emphysema and diabetes. Their production during exercise is involved in delayed onset muscle soreness (DOMS) and elevated fatigue, though this remains uncertain.

Exercise accelerates the metabolic processes in the body and thus increases the speed of oxidation. This is like a car rusting. Hence, oxidation is a harmful process that prematurely ages tissue. Antioxidants help prevent this process and so they can limit the damage it does. This is not a sensationalist and unsubstantiated claim just limited to the headline grabbing media. For many years the scientists have claimed that exercise can boost free radical activity by as high as 50-100 fold. This is a tremendous increase and it is easy to imagine how such a reaction can cause the aforementioned adverse effects.

Diseases caused by free radicals such as those listed above are so prevalent in the modern world that it makes one wonder if exercise is not doing more harm than good. Perhaps we would have been a lot better off spending our time drinking in the bar as we know that moderate alcohol intake is beneficial for our heart. It is, therefore, easy to understand why it makes sense for athletes to take high doses of antioxidants such as vitamin E and C to prevent these harmful effects.

Do We Need Free Radicals at All?

But we can relax; the scientists have gotten it wrong. Our bodies deserve more credit than we just give them. When we exercise our bodies happen to adjust to limit free radical production and this increase is more likely in the region of 2-4 fold, rather than initially thought 50-100 fold. While previously considered as a negative phenomenon, ample evidence now suggests that this 2-4 fold increase in free radicals is in fact good for us, inducing positive adaptations in skeletal muscle and enhancing our cellular health.

This phenomenon is known as the hormesis effect. It happens when a tiny amount of a normally toxic substance provides benefits to our health. In regards to exercise, we experience a benefit from free radical formation by taking part in non-exhaustive types of exercise that most of us participate in. Such exercise up-regulates our own antioxidant production, elevating our resistance threshold to oxidative stress. Trained individuals display increased basal heat shock protein, superoxide dismutases 1/2 and glutathione peroxidase content (all body’s own beneficial antioxidants). It is known that in order to build muscle it is necessary to cause small amount of damage to our muscles first. In the same way, in order to enhance our antioxidant defence systems we need exposure to small amounts of free radicals first.

The theory has it that the human genome was chosen in a time of habitual physical activity. Regular exercise and its resulting cellular effects restore signalling systems to their original evolutionary levels. However, if we use high doses of dietary antioxidant supplements, we prevent this adaptation process, thus lessening the benefits. For instance, antioxidant supplementation with vitamin C (1g/day) has been proven to cause delayed recovery from exercise and worsening performance capabilities in runners. Dietary antioxidants have in the same way being shown to inhibit the crucial signalling pathways for exercise induced insulin sensitisation.

However, in exhaustive/endurance types of sports such as marathon the stress of a long run and the surge in free radicals produced are most probably in excess of what the body was designed to cope with. In such instances the chronic exposure to reactive oxygen species (ROS) may cause muscle cell death. Therefore, in exhaustive/endurance sports antioxidant supplementation may be advisable.

To conclude, we should say that our free radical/antioxidant (REDOX) status in our bodies is a complex system essential for many vital aspects of health. We simply do not have enough knowledge and experience to mess up with high doses of antioxidants.

But if you are concerned with the consequences of elevated free radical levels from strenuous exercise, a much better approach would be to supplement with precursors of the bodies’ own antioxidants such as n-acetyl cysteine. This substance is needed for production of the antioxidant glutathione peroxidase and so it enables our bodies to regulate our antioxidant activity naturally. It is suggested that such a strategy may increase time to exhaustion in endurance trained athletes. A diet rich in fruit and vegetables will provide a wide variety of natural dietary antioxidants, allowing our bodies to work uninterrupted as they know best.

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