Half of French people declare practicing a sporting activity. Practiced moderately but continuously throughout life, sports undoubtedly have a beneficial effect on health. It plays an important role in the prevention and management of certain diseases such as osteoporosis, arthritis, cardiovascular diseases, or diabetes. Regular exercises strengthen the heart, reduce the effects of stress, and maintain muscle energy. However, sports also have their disadvantages: if practiced too intensively, especially without appropriate training, it can promote the onset of oxidative stress.
Antioxidants and resistance to pollution
During physical exercise, the body needs much more oxygen than usual. Oxygen consumption can thus be increased up to forty times during a period of intensive exercise. This increase results in a greater production of free radicals. A number of experimental studies have highlighted the formation of free radicals. Thus, in animals subjected to intensive exercise, it is observed that the concentration of free radicals is multiplied by two or three, in the muscles and in the liver, compared to the resting state. More recently, a study involving 12 men practicing amateur weightlifting indicated that, in men, the practice of high-intensity exercise increases the production of free radicals.
When antioxidant defenses are strong enough to neutralize them before they damage cell membranes, DNA, or other cellular structures, free radicals are not a problem. But when there are not enough antioxidants, it is oxidative stress. Free radicals can then cause considerable damage to tissues in general and muscles in particular. They can also be responsible for a decrease in recovery capacity and a weakening of the immune system. No athlete escapes oxidative stress, not even well-trained elite athletes.
A weapon against radical damage
Vitamin E, at the level of cell membranes and lipoproteins, is the main scavenger of free radicals. It neutralizes their effects and reduces oxidative stress. Studies show that, in muscles, vitamin E levels decrease during physical exertion. This means that an athlete who does not take vitamin E supplements is subjected to a probably four times greater radical bombardment than that endured by a sedentary person: twice as many free radicals and twice as little vitamin E.
The occasional athlete
If, after sitting all week in his office, an individual suddenly decides to spend almost all of his weekend on a bicycle or windsurfing board, he will be much more sensitive to oxidative stress than a person who regularly engages in sports. Indeed, regular training seems to stimulate the antioxidant defense system and decrease lipid peroxidation. When sedentary, it is therefore particularly important to seriously strengthen antioxidant defenses before going away for the weekend and getting on a bike or windsurfing board. A balanced diet, with at least five daily portions of fruits and vegetables, is an essential starting point. But this is rarely enough. Because for physical exercise to be truly beneficial for health, an adapted consumption of antioxidants is needed. Antioxidant nutritional supplements may be necessary in this case.