Antioxidants are substances produced within the body or obtained through the diet which protect the body from free radicals. Exercise can increase the formation of free radicals and may lead to cell damage, injury and fatigue. Antioxidants may play a role in preventing cellular injury caused by exercise and delaying muscle fatigue.
Free radicals are unstable and destructive molecules known to react with cells causing damage and abnormal function. Free radicals are created in a number of ways, such as by radiation from the sun, x-rays and industry; nitrous oxide from automobile exhausts; from cigarette smoke, alcohol, saturated fat; and from chemicals found in food, water and air. Free radicals are also created during normal metabolic processes such as the production of energy within the cell.
To protect itself, the body has its own antioxidant defense system made up of enzymes such as superoxide dismutase (SOD), catalase and glutathione peroxidase. These are also known as endogenous antioxidants because they are produced within the body. Many of the antioxidants we need to protect our cells from free radical damage also come from the foods that we eat, including substances such as vitamin C, vitamin E, selenium, beta carotene and coenzyme Q10. Many other vitamins, minerals, enzymes and herbs act as antioxidants or aid in the production of the body's own antioxidants.
Many studies have investigated the effect of exercise on free radical production. Most indicate that free radical production is increased during exercise and that the activity of the body's antioxidant defences is increased to help compensate, especially in trained athletes.
It is well established that deficiencies of certain antioxidant nutrients such as vitamin C can lead to impairment in sports performance. Some studies have shown that: - Taking certain antioxidants (in particular vitamin E and vitamin C) can help protect muscle cells from exercise-induced free radical damage. - Vitamin E can increase circulating levels of certain white blood cells (neutrophils) in older people who exercise. - Vitamin E may improve skeletal muscle repair. - Vitamin E may improve blood sugar control (including insulin sensitivity) in healthy people. - Vitamin C and vitamin E do not appear to affect sports performance. Antioxidant supplements may be beneficial for people who engage in regular, heavy exercise.
VITAMINS/MINERALS/HERBSRemember that taking a single type of antioxidant (just vitamin C, or just vitamin E for example) in high doses is not recommended. Antioxidants work together to neutralise free radicals and if taken in isolation, may actually increase free radical production. Also remember that supplements are no substitute for a healthy, balanced diet. In general, the darker green or more vibrantly colourful fruits and vegetables have the richest antioxidant content.